Proposed LCD - Superficial Radiation Therapy (SRT) for the Treatment of Nonmelanoma Skin Cancers (NMSC) (DL39808) (2024)

Document Information

Coverage Guidance

Coverage Indications, Limitations, and/or Medical Necessity

Coverage Guidance

Compliance with the provisions in this LCD may be monitored and addressed through post payment data analysis and subsequent medical review audits.

History/Background and General Information

Nonmelanoma skin cancers (NMSC) such as squamous cell carcinoma (SCC) or basal cell carcinoma (BCC) are a type of keratinocyte carcinoma and are the most common malignancies reported in the United States of America (U.S.).^1-3 In 2015, Rogers et al. analyzed claims data from 2006 through 2012 for total claims filed in both the Total Claims Data Set and the Medicare Limited Data Set and found that NMSC was the most common malignancy treated based upon CPT codes. In addition, they noted that the incidence of diagnosed NMSC increased 35% from 2006 through 2012.² Unfortunately, the prevalence of NMSC is generally not reported or tracked by national cancer registries.³ However, the total number of procedures for skin cancer treatment in the Medicare population increased by 13% from 2,048,517 in 2006 to 2,321,058 in 2012.² Even though the exact prevalence of NMSC may be unknown, the American Cancer Society estimates that 5.4 million basal and squamous cell skin cancers are diagnosed each year in the U.S. occurring in approximately 3.3 million people.³

There are multiple modalities available for the treatment of cutaneous NMSCs. Predication of treatment is often based upon the most reasonable alternative that will give the highest likelihood of cure with the least associated morbidity. Such treatment options include electrodessication and curettage, topical chemotherapeutic agents, simple surgical excision, complex surgical excision with or without frozen section, micrographically oriented histographic surgery (Mohs), external beam radiation therapy (EBRT), and SRT including EBT.^4,5,7-13 More recently, there have been some reports of combining the use of image guidance (IG) via high resolution ultrasound (HRUS) with SRT (IGSRT) or EBT (IGEBT) in order to improve the outcomes and diminish the recurrence rates; the effectiveness of this additional modality is currently under active investigation.^14-19

According to the National Comprehensive Cancer Network^® (NCCN^®) and the American Academy of Dermatology Association (AAD) guidelines, treatment is based upon the stratification of SCC and BCC into risk factors based upon the likelihood of recurrence.^4,5,8,9

Per NCCN^® guidelines for BCC,⁴ the stratification elucidated below should be used to determine the treatment for local BCC based on the following risk factors for recurrence (any high-risk factor places the patient into the high-risk stratification group): low-risk BCC and high-risk BCC.

Similarly, NCCN^® stratification guidelines for local SCC or SCC in situ are based on risks factors for recurrence and are stratified into low-risk, high-risk and very high-risk.⁵ Risk category assignment should be based on the highest risk factor present. The high-risk group has elevated risk of local recurrence; the very-high-risk group has elevated risk of local recurrence and elevated risk of metastasis. Deep invasion for SCC is defined as invasion beyond the subcutaneous fat OR >6 mm (as measured from the granular layer of adjacent normal epidermis to the base of the tumor, consistent with the American Joint Committee on Cancer (AJCC) Staging Manual, 8th Edition).²⁰ The very high-risk SCC is not amenable to SRT, and the depth is measured before any preoperative curettage or other treatment to the lesion.

Narrow excision margins due to anatomic and functional constraints are associated with increased recurrence rates with standard histologic processing. Complete margin assessment such as with Mohs or peripheral and deep en face margin assessment (PDEMA) is recommended for optimal tumor clearance and maximal tissue conservation per NCCN^® guidelines for both SCC and BCC.^4,5 Very high risk SCC should be treated with surgical excision with PDEMA or Mohs micrographic surgery (MMS) with/without adjuvant RT based upon consultation with a radiation oncologist per NCCN^® guidelines OR EBRT.⁵

Current published and recommended guidelines exist from NCCN^®, AAD, the American Society of Radiation Oncology (ASTRO), and the American Brachytherapy Society (ABS). Recommended treatment of cutaneous NMSC is based upon a consortium of experts and peer-reviewed literature.^4-11

The focus of this LCD will pull information from literature including published societal guidelines and published peer-reviewed articles. No changes are recommended for currently approved indications for EBRT and MMS for the treatment of NMSC. Peer-reviewed, published evidence supporting the use of SRT and the subset EBT will be utilized to help establish guidelines for the appropriate usage of these modalities for the Medicare population.

BCC is the most common form of human cancer with a continued increase in annual incidence and is closely followed by SCC in the U.S.^1-3,8,9 While several options for treatment exist, the majority of NMSCs are treated surgically, either with a traditional surgical excision or MMS.

SRT has also been a long-standing, optional treatment by dermatologists and radiation therapists but had been relegated to a second line treatment option for patients who were not surgical candidates or who refused surgical treatment. In addition, there are no prospective or randomized clinical trials (RCTs) in the peer-reviewed literature that compare the outcomes in recurrence rates (long-term 5 years or more, short-term less than 2 years) between MMS or surgical excisions and SRT. In addition, with the advent of newer SRT technology, the reported recurrence rates have improved and are near the MMS rates although there is no consistent reporting of the histology sub-types and comparison of sub-groups with the higher risk NMSCs that are typical of MMS procedures.^10-15,21-24 Furthermore, several authors have purported to using IGSRT and IGEBT as being more effective than SRT or EBT alone, although there are no randomized clinical studies or prospective studies to show that the additional use of high-resolution ultrasound guidance (HRUS) improves the short-term and long-term recurrence rates.^14-16

SRT utilizes x-rays or photons to deliver electromagnetic energy to cells that are rapidly dividing in order to stop mitosis. SRT machines deliver low energy Kilovoltage (kV) in the range of 50 to 150 kV per treatment. The machines used to deliver superficial treatment spare the deeper structures and are ideal for treating cutaneous malignancies.¹³ EBT is a variation of SRT except that a high dose x-ray source is placed directly into a skin applicator close to the surface and provides a hom*ogenous dose pattern in the treatment area to a specified depth. EBT also delivers low-energy radiation at a high dose rate through an application that is placed on the skin typically less than 120 kilovoltage photons (kVp) as compared to traditional brachytherapy.^13,25 Both SRT and EBT can be produced by commercially available devices^10,13 and are utilized in the outpatient dermatology office or radiation oncology setting.

Covered Indications

The medical record documentation must support the medical necessity for the use of SRT as the primary modality for treatment of the NMSC.

If the beneficiary meets all the criteria as outlined in the LCD, the use of SRT is considered reasonable and necessary for the following conditions:

1. The presence of a low-risk cutaneous BCC or high-risk BCC as per NCCN^®, ASTRO, and AAD guidelines with documentation that the patient is a nonsurgical candidate;^4,8,10 OR
2. The presence of a low-risk cutaneous SCC or high-risk SCC as per NCCN^®, ASTRO, and AAD guidelines with documentation that the patient is a nonsurgical candidate;^5,9,10 OR
3. The presence of a cutaneous SCC in situ as per NCCN^®, ASTRO and AAD guidelines with documentation that the patient is a nonsurgical candidate.^5,9,10

Coverage Requirements for the Use of HRUS for IGSRT

The use of HRUS is not considered reasonable and necessary and is not supported by the literature except as follows¹⁰:

1. The use of HRUS may be reasonable and necessary for tumor staging and pre-planning purposes to determine the depth, size and stage of the tumor prior to the delivery of SRT.
2. The continued use of HRUS during the fractionated treatment sessions is not reasonable and necessary except for high risk NMSCs. The use of HRUS may be reasonable and necessary if it is determined there is a significant clinical change in the status of the tumor during the ongoing SRT treatments and imaging is required to adjust treatment dosing for high risk NMSCs. Medical documentation should support this rationale for the further use of HRUS.

Coverage Requirements for the Use of EBT

Based upon the consensus of the literature and the recommendations of the AAD, ASTRO and ABS, the use of EBT for the treatment of NMSCs is not considered reasonable and necessary at this time. There is insufficient long-term efficacy and safety data to support the routine use of electronic surface brachytherapy.^12,13,26

Limitations for SRT and IGSRT

The following are considered not reasonable and necessary:

• First line treatment option in surgical candidates;
• The use of SRT and IGSRT for the treatment of advanced BCC and SCC;
• The use of SRT and IGSRT for the treatment of patients with NMSCs who have contraindications to RT;
• Cutaneous tumors arising in previously irradiated fields or where overlapping fields would be expected;
• Cutaneous SCC with size greater than 4 cm⁵;
• Cutaneous BCC with size greater than 4 cm¹⁴;
• Cutaneous NMSCs with depth greater than 6 mm^5,14,19;
• Cutaneous NMSCs with aggressive morphology^27,28;
• Cutaneous tumors with perineural or perivascular invasion as sole treatment option^4,5,10; and
• Very high-risk SCC^5-7,9,10.

Provider Qualifications

For purposes of Centers for Medicare and Medicaid Services (CMS) classification and ASTRO guidelines, the delivery of SRT with or without HRUS would fall under the auspices of RT delivered in a free-standing RT center. Delivery of SRT in an office setting would be treated similar to a free-standing RT center.

RT services furnished in a freestanding RT center are covered under a separate benefit category from therapeutic services provided in a hospital outpatient department. Freestanding center radiation therapy services are specifically covered under Section 1861(s)(4) of the Social Security Act (SSA). Further guidance pertinent to physician supervision of these services is provided in Chapter 15, Section 90 of the Medicare Benefit Policy Manual. Direct personal supervision by a physician is required for RT services provided in the freestanding setting. Although the Code of Federal Regulations (CFR) does not define “direct personal supervision”, the Medicare Benefit Policy Manual does provide a description that is similar to the definition of “direct supervision” under the CFR. The physician does not need to be in the same room where the therapeutic service is performed but must be in the area and immediately available to provide assistance and direction throughout the performance of the procedure.

The immediate availability by the supervising physician is 1 of the requirements that must be met to support therapeutic services in the freestanding setting. For example, if the supervising physician becomes unavailable to directly supervise the services, and no other supervising physician is available, then any RT delivery services provided during the physician’s absence cannot be covered by Medicare.^29-32

This practice parameter was revised collaboratively by the American College of Radiology™ (ACR) and ASTRO.^29,30,32 Image-guided radiation therapy (IGRT) is RT that employs imaging to maximize accuracy and precision throughout the entire process of treatment delivery. This process can include target and normal tissue delineation, radiation delivery, and adaptation of therapy to anatomic and biological and positional changes over time in individual patients. This practice parameter focuses on image-guidance at the time of radiation delivery to ensure its adherence to the planned treatment, referred to as in-room IGRT (hereafter referred to simply as IGRT). Circ*mstances that may require the use of IGRT include the treatment of morbidly obese patients (where external landmarks are not reliable) or any patient factor that would decrease reproducibility of an intended treatment position. Common indications for IGRT include any target volume located near or within critical structures and/or in tissue with inherent setup variation, any target volume in close proximity to critical structures that must be protected, any volume of interest that must be covered with narrow margins to adequately protect immediately adjacent structures, any target volume that is subject to daily variation that is due to internal motion, any target where the adjacent area has been previously irradiated and abutting fields must be precise, or any scenario in which dose escalation is planned beyond the usual doses for similar tumors.

I. QUALIFICATIONS AND RESPONSIBILITIES OF PERSONNEL

*See the ACR–ARS Practice Parameter for Radiation Oncology and the ACR–ASTRO practice parameter for image-guided radiation therapy (IGRT) ^29,30 in which qualifications, credentialing, professional relationships, and development are outlined. If this certification did not include IGRT, then specific training in IGRT should be obtained before performing IGRT.

1. Radiation Oncologist: The responsibilities of the radiation oncologist include, but are not limited to, the following:
   1. The radiation oncologist will manage the overall disease-specific treatment regimen, including careful evaluation of the patient and disease, assessment of comorbidities and previous treatments, thorough exploration of various treatment options, discussion with patients regarding the impact of treatment (i.e., benefits and potential harms), implementation of IGRT as outlined below, on-treatment evaluation and documentation during the course of treatment, and follow-up after treatment as indicated.
   2. The radiation oncologist will document a proper patient positioning method with attention to disease specific targeting concerns; patient-specific capabilities; patient comfort; stability of setup; and accommodation of devices as required for targeting through the IGRT approach. This document, often in the form of a simulation note or simulation order, will specify whether and how techniques will be employed to account for intrafraction and interfraction target movement and the potential residuals from on-board image registration, localization, and correction procedures.
   3. The radiation oncologist will supervise the patient’s simulation using appropriate imaging methods. The radiation oncologist should be aware of the spatial accuracy and precision of the simulation modality and the IGRT delivery. Steps must be taken to ensure that all aspects of simulation, including positioning, immobilization, and accounting for inherent organ motion, are properly carried out using IGRT in a consistent fashion.
   4. Once the planning images have been acquired, they will be transferred to the treatment-planning system (TPS). The radiation oncologist will contour the target(s) and regions of interest (subclinical targets). Various imaging studies known to be useful for the specific disease treated should be fused into the planning dataset for targeting. Subsequently, the radiation oncologist will delineate the proper planning target volume (PTV) beyond the clinical target volume (CTV) or gross tumor target volume (GTV). In addition to these tumor targets, the radiation oncologist will confirm that relevant normal tissues adjacent to and near the target organs at risk (OARs) are contoured. The radiation oncologist, working with the physicist/dosimetrist, will review dose volume histogram (DVH) before approving the plan, ensuring volume constraints are met. Locating and specification of the target volumes and relevant critical normal tissues will be carried out after consideration of all relevant imaging studies.
   5. The radiation oncologist will document case-specific expectations for prescribing the radiation dose to the target volume and set limits on dose to adjacent normal tissue via a dose volume constraint form or directive. Certain normal tissues may need to be tracked with the IGRT process just as with the tumor target(s). The radiation oncologist will then approve the final treatment plan in collaboration with a medical physicist and dosimetrist.
   6. The radiation oncologist will be responsible for deciding what are the acceptable or unacceptable day-to day variations in the treatment setup or provide the acceptable limit on movements as part of the IGRT directive.
   7. Images, if required prior to or for treatment alterations are reviewed either offline between treatments, online immediately prior to a treatment, or in real time during treatment delivery.
2. Qualified Medical Physicist: See the ACR-AAPM Technical Standard for Medical Physics Performance Monitoring of Image-Guided Radiation Therapy (IGRT) for the qualifications of the Qualified Medical Physicist.
3. Medical Dosimetrist: The responsibilities of the medical dosimetrist, or otherwise designated treatment planner, should be clearly defined and should include the following:
   1. Being available for the simulation of the patient to ensure proper patient setup with the appropriate immobilization device.
   2. Ensuring proper orientation of volumetric patient image data on the radiation TPS to facilitate accurate target delineation and field design.
   3. Contouring relevant normal structures (i.e., OARs).
   4. Designing and generating the treatment plan under the direction of the radiation oncologist and medical physicist.
   5. Generating all technical documentation required to implement the IGRT treatment plan.
   6. Being available for the first treatment and assisting with verification for subsequent treatments as necessary.
   7. To work closely with the qualified medical physicist in ensuring that plans created by the TPS can be realistically delivered on the linear accelerator.
4. Radiation Therapist: The responsibilities of the radiation therapist should be clearly defined and should include the following:
   1. Understanding and proper training in the use of the patient immobilization/repositioning system and fabricating and understanding the proper use of devices for IGRT.
   2. Under the supervision of the radiation oncologist and Qualified Medical Physicist, performing initial (planning) simulation of the patient and generating the medical imaging data appropriate for the TPS.
   3. Implementing the IGRT treatment plan under the supervision of the radiation oncologist and the Qualified Medical Physicist or of the medical dosimetrist under the direction of the medical physicist.
   4. Coaching patients as needed during radiation delivery while utilizing motion management or adaptive techniques.
   5. Acquiring verification images for review by the radiation oncologist as prescribed.
   6. Notifying the radiation oncologist and/or medical physicist when setup variations are unacceptable, or shifts exceed the tolerable threshold defined in the IGRT directive.
   7. Notifying the radiation oncologist of any patient concerns or discomfort with the current setup and positioning.

II. Diagnostic x-ray tests may only be furnished under the supervision of a physician. Services furnished without the required level of physician supervision are not covered under Medicare. All diagnostic tests furnished in the freestanding setting must follow the physician supervision requirements for the individual tests as indicated above. Direct supervision of diagnostic x-ray tests including HRUS in the freestanding center requires a physician be physically present in the office suite and immediately available to furnish assistance and direction. Nonphysician practitioners cannot function as supervisors of diagnostic tests performed in conjunction with RT.

III. Regarding clinical qualifications for the supervising provider of freestanding RT services, CMS only indicates that direct personal supervision by a physician is required.

IV. IGRT uses imaging to maximize accuracy and precision throughout the process of full treatment delivery, not just during treatment planning. IGSRT uses HRUS for the treatment planning; however, it is not utilized throughout the entire process of full treatment delivery. Therefore, the use of HRUS is for planning purposes prior to treatment initiation or simulation and prior to subsequent treatments. HRUS does not meet the criteria as being used during full treatment delivery as other imaging modalities used for IG such as cone-beam CT or MRI scanning to target the tumor being treated are utilized. The medical necessity for the imaging modality and frequency must be assessed and documented on each patient’s medical record.

Summary of Evidence

A literature search was conducted using the following key terms: SCC, BCC, SRT, EBT, RT, Mohs, surgical excision of skin cancer, IGSRT, IGEBT, recurrence rates and societal guidelines including NCCN^®,AAD, American College of Mohs Surgery (ACMS), ASTRO and ABS. Additional sources included PubMed and Hayes Knowledge Center. The literature search included published peer-reviewed literature and published societal guidelines within the last 25-30 years with greater emphasis placed upon literature from the last 15 years. Retrospective studies involving larger sample sizes were included in order to gather as much evidence as possible; although RCTs and prospective RCTs were more useful in the analysis of current evidence. Case reports and case series were excluded due to low quality of evidence. Poster presentations and unpublished reports were not included in the analysis. Published societal guidelines and recommendations were considered in the analysis as supported by the literature.

Introduction:

NMSCs or keratinocyte carcinomas are predominantly BCCs and SCCs. There are numerous treatment options available to treat these cutaneous malignancies including electrodessication and curettage, topical immunomodulators or chemotherapeutic agents, photodynamic therapy, surgical excision with and without frozen section diagnosis, MMS, RT as primary or adjuvant therapy and multi-modality therapy for advanced or systemic disease. Untreated or recurrent cutaneous malignancies can result in significant morbidity and mortality upon further progression of disease. The goal of therapy is to minimize recurrence(s) while taking into consideration associated comorbidities, size and location of the lesion(s), histology of the lesion(s) and ultimate outcome whether it be surgical or nonsurgical treatment.^4-9

Evidence-Based Guidelines for Standard of Care

According to NCCN^®, which is based upon a consortium of leading experts in the disciplines of dermatology, diagnostic/interventional radiology, oncology, internal medicine, otolaryngology, pathology, dermatopathology, reconstructive surgery radiation oncology and surgical oncology, consensus guidelines have been established for the treatment of BCC and SCC.^4,5 Furthermore, the preferred treatment options have been stratified by “high-risk” or “low-risk” based upon risk factors for the likelihood of recurrence.^4,5

From NCCN^® guidelines, for low-risk BCC, the recommended principal of treatment is the complete removal of the tumor and maximal preservation of function and cosmesis. Other non-surgical options may also be considered for superficial BCC including topical therapy, photodynamic therapy (PDT) or cryotherapy. Alternatively, RT for non-surgical candidates is a recommended option with a high cure-rate and low rate of reported recurrences. The NCCN^® acknowledges that surgical approaches often offer the most effective and efficient means of accomplishing cure with evaluation of pathology; however, they also note considerations of function, cosmesis and patient preference may lead to the choice of RT as primary treatment over surgery.⁴ These recommendations are also consistent with the AAD⁸ and ASTRO.¹⁰

For high-risk BCC, Mohs surgery or other forms of PDEMA would be considered the primary form of treatment due to the higher likelihood of recurrence and more aggressive nature and location of the lesion.⁴ For patients who are non-surgical candidates, the NCCN^® recommends that the appropriateness of RT should be performed by a radiation oncologist.⁴ Furthermore, the AAD and ASTRO agree that RT is a viable primary treatment for non-surgical candidates.^6-8,10

From NCCN^® guidelines, for low-risk SCC, the recommended principle of treatment is the complete removal of the tumor and maximal preservation of function and cosmesis. In patients with squamous cell in-situ (SCCIS), alternative therapies such as topical therapy, PDT and cryotherapy may be considered. Alternatively, RT for non-surgical candidates is a recommended option with a high cure-rate and low rate of reported recurrences. The NCCN^® acknowledges that surgical approaches often offer the most effective and efficient means of accomplishing cure with evaluation of pathology; however, they also note considerations of function, cosmesis and patient preference may lead to the choice of RT as primary treatment over surgery.⁵ These recommendations are also consistent with the AAD⁸ and ASTRO¹⁰.

For high-risk SCC, Mohs surgery or other forms of PDEMA would be considered the primary form of treatment due to the higher likelihood of recurrence and more aggressive nature and location of the lesion.⁵ For patients who are non-surgical candidates, the NCCN^® recommends RT as an option and the determination of the appropriateness of RT should be performed by a radiation oncologist.⁵ Furthermore, the AAD and ASTRO agree that RT is a viable primary treatment modality for non-surgical candidates.^6-8,10

In general terms, low-risk BCC and low-risk SCC have many appropriate treatment options including surgery, non-surgical topical treatments and RT. For high-risk NMSCs, MMS shows a consensus for higher cure rates based upon both prospective, randomized and large population retrospective cure rates with long-term follow-up and low recurrence rates compared to traditional surgical excision and superficial and traditional RT.^{8,9,12,13,27,28,33-37}

Evidence Based Guidelines for Definitive Radiation Therapy (RT)

ASTRO convened a task force to address the use of definitive RT for the treatment of patients with cutaneous SCC and BCC and to formulate evidence-based guidelines using the available published literature. The evidence review came up with the findings that there were limited, well-conducted and randomized studies for the treatment of SCC and BCC with RT. Most of the studies paradigms were limited to the head and neck region. They also stated that definitive RT is an effective modality for the local control of BCC and SCC with the caveat that the RT approach is stymied by the absence of prospective randomized trials comparing surgery with RT. However, ample retrospective and single-arm prospective studies show that definitive RT is associated with high local control rates.¹⁰

An article involving a multi-disciplinary approach from the University of Texas involving the Departments of Dermatology, Radiation Oncology and Head and Neck Surgery was published in the Journal of the American Academy of Dermatology. The recommendation for definitive RT for BCC was for patients who were poor surgical candidates and for tumors that when excised would result in significant morbidity, impaired function or poor cosmesis. Recommendations for definitive RT were similar for cutaneous SCC.⁷

ASTRO guidelines for BCC and SCC note the following: The guideline recommends definitive RT as primary treatment for patients with BCC and cutaneous SCC who are not surgical candidates while conditionally recommending RT with an emphasis on shared decision-making in those situations in which adequate resection can lead to a less than satisfactory cosmetic or functional outcome. Furthermore, the consensus guidelines note that the role of RT in the management of BCC and SCC is hindered by a lack of high-quality evidence specifically in randomized comparisons and prospective randomized studies.¹⁰

Evidence Based Guidelines for Superficial Radiation Therapy (SRT)

SRT has been used for more than a century to treat cutaneous malignancies; however, the usage has fallen out over time and is no longer taught as part of most dermatology residencies and has become more commonly used by radiation oncologists. The requirement of standardized didactic instruction in dermatology residency ACGME program requirements, combined with opportunities for hands-on experience, represents the best practice in residency education. Currently, there is no specific ACGME program requirement for either didactics or clinical experience in radiotherapy.³⁸ The emergence of newer SRT technology has allowed for the greater usage by dermatologists in the last 15 years within their offices. In fact, the bulk of claims coming through processed for SRT are from dermatologists as opposed to radiation oncologists.⁶

SRT uses low energy photons produced by a kV X-ray machine. Radiation is then absorbed by the cutaneous tissue without deeper penetration and unlike EBRT, a bolus is not required because the dosage decrease outside the radiation field is minimal. In addition, SRT consists of RT utilizing X-rays that are more penetrating than Grenz rays but less penetrating than traditional orthovoltage external beam irradiation.^6,13

A retrospective analysis on 1,715 cutaneous cases of BCC and SCC treated with SRT from 2000 to 2010 found of the 1,715 tumors reviewed during this period, 712 were histologically proven BCC (631 nodular and 81 superficial), 994 were SCC (861 SCCIS and 133 invasive SCC), and 9 displayed distinct features of both BCC and SCC in the same biopsy specimen.²⁷ Kaplan-Meier estimates (with 95% confidence intervals) of cumulative recurrence rates of all tumors at 2 and 5 years were 1.9% (1%-2.7%) and 5.0% (3.2%-6.7%), respectively; of BCC at 2 and 5 years were 2% (0.8%-3.3%) and 4.2% (1.9%-6.4%), respectively; and of all SCC at 2 and 5 years were 1.8% (0.8%-2.8%) and 5.8% (2.9%-8.7%), respectively. The authors also found a higher recurrence rate for tumors greater than 2 centimeters (cm) in size. Tumors regarded as aggressive were either treated with MMS or a referral was made to a nearby teaching hospital if the patient declined surgery and opted for RT. The limitations for the study included no treatment of aggressive BCC or SCC with SRT. They also concluded that the although the recurrence rates are excellent for nonsurgical patients, they are not superior to the reported recurrence rates with MMS. Cosmetic outcomes were not tracked in this study and the most common unfavorable side effect was reported to be hypopigmentation with an increase in telangiectasias.

In another study, SRT was used to treat BCC and SCC in 1,267 patients from 1988 through 1992. In their retrospective analysis, the overall recurrence rate was 5.1% with a higher incidence in larger tumors and increased tumor thickness. The limitations of the study include the retrospective nature of the study, lack or randomization and no differentiation in patient histology sub-types. There was also no randomization for the stratification of different fractionation protocols during the study.³⁹

One study found a higher recurrence rate in patients treated for BCC that exhibited the sclerosing subtype and excellent results in patients treated with the nodular subtype. In their retrospective study of 48 patients treated with SRT, patients were looked at for recurrence based upon subtype. They found the estimated 5-year recurrence rate for all patients with BCC was 15.8%: 8.2% for patients with the nodular subtype, 26.1% for patients with the superficial subtype, and 27.7% for patients with the sclerosing subtype (Kaplan–Meier analysis: P = 0.055). The median follow-up was 48 months. The mean time to recurrence was 20 months, and 86.4% of all recurrences occurred within 3 years after treatment. The limitations of the study were retrospective in nature and lack of randomization for treatment and different fractionation regimens.²⁸

A retrospective analysis of 180 large SCCs treated with SRT between 1960 and 2004 was conducted. The authors reported the following: Mean tumor size was 3.5 square cm (SD 7.5) and mean follow-up period was 4.9 years (SD 4.7). Relapse-free survival was 95.8% after 1 year and 80.4% after 10 years. Two-year relapse-free survival was 94.8% for good, 88.9% for moderate and 85.7% for poorly differentiated tumors. Five-year relapse-free survival was highest in SCCs located around the eyes (100%) and cheeks (90.9%). A significant limitation of the study included information about the localization of the relapses and whether the relapse was in-field versus at the irradiation margins. Also, as tumor thickness was not retraceable in the majority of cases, classification of the tumors according to the AJCC was not possible. Furthermore, patient selection was individually performed and there were no standardized inclusion criteria as this was a retrospective study. Therefore, biases in patient selection, patient referral (as this study was performed in a center) and classification are possible. The authors concluded that larger prospective clinical trials are required to confirm the achieved results.²⁴

In summary, the AAD and ASTRO both have adopted clinical practice guidelines for RT in the treatment of basal and squamous cell skin cancers and suggest similar cosmetic outcomes and local control rates among these radiotherapeutic modalities, with many large case series reporting local control rates of over 90%. Randomized trials comparing the efficacy of different radiotherapeutic modalities would be difficult to undertake due to an increased risk of recurrence, morbidity, and possible mortality in patients randomized to receive RT alone compared to surgery.^6,10 Cosmetic outcomes are reportedly similar, although none of the SRT studies have specifically studied cosmetic outcomes versus reconstructive outcomes after surgical resection. The literature does support overall excellent cosmetic outcomes after skin cancer resection.⁴⁰

Evidence Based Guidelines for Electronic Brachytherapy (EBT)

Nestor et al provided consensus guidelines for the use of SRT and EBT. Their findings noted that EBT should be considered short-contact SRT, since the energy source is the same and the technology is virtually identical to short-contact SRT devices. SRT is superior to electronic surface brachytherapy (EBT) based on its abilities to vary energies from 50 to 100cGy and employ larger spot sizes.¹² In contrast to EBT, clinical data on thousands of patients support long-term cure rates and cosmesis with SRT.

A growing set of literature exists regarding the use of EBT for NMSC, though follow up remains short. Initial studies demonstrated the feasibility of the technique with limited acute toxicity.^25,26 Updated outcomes at 1 year confirmed no recurrences and toxicity profiles that were consistent with other radiotherapy techniques, including no Grade 3 toxicities.⁴¹

The largest series to date, is a pooled analysis of 1,259 patients (1,822 lesions) from 6 publications, treated between 2009 and 2014. Patients were treated to 40 to 45Gy in 3 to 8 fractions with 95% of lesions being BCC or SCC. Lesions in this aggregate dataset were treated to 40 to 45Gy using 3 to 8 fractions with the majority being treated with eight fractions. Applications occurred 2 or 3 times a week with 36 to 48 hours between treatments. The majority of the lesions were BCC (57%) or SCC (38%) and less than 2 cm in size (97%). The lesions were treated to a depth of 3 mm or less below the surrounding skin surface in 90% of the cases. Most patients had follow-up less than 1 year (926) with only 47 patients having follow up beyond 3 years; the recurrence rate was 0.97%. The most common long-term skin surface change was relative hypopigmentation. It should be noted that although these data are pooled, there is limited data comparing EBT with other radiotherapy or surgical techniques. There are many limitations of the study including lack of randomization, different fractionation protocols, no stratification by tumor sub-types, small lesion sizes [less than 2 cm in size (97%)] being treated and the low percentage of patients being seen after 1 to 2 years. Therefore, due to the short follow-up in this study, recurrence rates with this technique cannot be extrapolated over the long-term.⁴³

In a second series, 127 patients (154 lesions) were evaluated retrospectively and with a median follow up of 16 months, the local recurrence rate was 1.3%; however, the Grade 3 acute dermatitis rate was 13% with no late Grade 3 toxicities (Grade 2: 5.8%). Limitations of this study included smaller sample size and short follow-up and lack of classification for the NMSCs including histology breakdown.⁴²

Patel et al. evaluated 369 patients (188 received EBT, 181 MMS) in a matched pair cohort study. The study was a retrospective chart review. Median age was 81 years old for the EBT cohort and 77 for the Mohs cohort; with 3.4 year mean follow up (2.6 to 4.3 years after EBT, and 2.3 to 5 years following MMS). No difference in rates of recurrence were noted with similar cosmetic outcomes. No comparisons were made between histological sub-types and only 2.4% of the NMSCs were greater than 2 cm in size in the 2 groups compared. A meaningful comparison is not likely since MMS typically is utilized to treat more aggressive histological subtypes and EBT is relegated to less aggressive histological sub-types and smaller tumors. In addition, further data comparing outcomes to surgery and other radiotherapy techniques are needed. Outcomes in younger patients are needed as they are underrepresented in this published series. Finally, the limitations of this study include the duration of follow-up as well as the non-randomization of the subjects.²¹

In a long-term retrospective study published, the authors reported a retrospective chart review of 183 patients with 185 lesions treated from 4 dermatology centers. Three subjects in the analysis were less than 5 years from the last treatment to follow-up visit. All lesions were stage 1 BCC, SCC, or SCCIS. Recurrence rate for the 183 subjects was 1.1%. Long-term skin toxicities were reported in 70% of the subjects. Hypopigmentation grade 1 was observed in 65.9% of the lesions, telangiectasia grade 1 was seen in 22.2%, scarring grade 1 in 2 subjects (1.1%), hyperpigmentation grade 1 in 2 subjects (1.1%), and induration grade 2 in 1 patient (0.5%). The induration grade 2 was located on the upper back and did not limit instrumental activities of daily living (ADLs). Multiple limitations of the study are present according to the authors. Although mean follow-up in the study was 7.5 years, which is the longest reported EBT result to date, this was not a randomized controlled trial designed to compare EBT with MMS in subjects with long-term follow-up. 59.6% of the 307 potential participants contacted did participate in the study. The remainder of the potential participants could not be contacted. Finally, the lesions were all stage I BCC or SCC and hypopigmentation was observed in 65.9% of the lesions, telangiectasia grade 1 in 22.2%. The results of this study show an unfavorable, long-term side effect of hypopigmentation and telangiectasias.²²

In a smaller prospective single-center, non-randomized study authors reported 26 patients with 44 lesions treated with EBT achieved 2 years follow-up. A complete response was documented in 95.5% of cases. Toxicity was reported as mild in all cases. Cosmesis was excellent in 88.6% of cases, and good in the rest. Change in pigmentation was the most frequent cosmetic alteration. The limitations of this study are non-randomization, small sample size, and limited follow-up to detect recurrence rates.²³

According to ABS, a consensus statement was released regarding EBT. Based upon the lack of published literature for EBT, they noted the following situations exist: 1. EBT units operate in the 50e70 kVp energy range, requiring little shielding and can therefore be used in a wide variety of settings including examination rooms and standard operating rooms; 2. Although EBT has been available for over 2 decades, there are no consensus dosimetry data available for these units creating safety issues for the patient and staff; and 3. Further clinical trials may be needed to establish clinical guidelines and consensus regarding whether to modify the prescription with EBT to account for potential differences in relative biological effectiveness (RBE) .¹¹

According to the ABS and ASTRO guidelines, there is growing data with respect to EBT and NMSC; however, there is a lack of comparative data to traditional treatments, limited data with long-term follow up, and a need for younger patients in studies before generalizing recommendations. Although data can be extrapolated from orthovoltage experiences with NMSC, considering the large numbers of patients diagnosed with NMSC, prospective studies with larger numbers of patients undergoing EBT should be performed.^10,11 Until mature outcomes are available, treatment for NMSCs should be performed in a clinical registry or trial at this time per ABS guidelines.¹¹ Further data with longer follow is required. Currently there are some studies looking at the effectiveness of HRUS to optimize EBT treatments in patients with NMSC.^44,45

Due to the lack of long-term randomized and controlled studies, ABS recommends that EBT is only to be used for the treatment of NMSC on a prospective clinical trial or registry at this time due to lack of mature data and comparative data with traditional radiotherapy techniques as well as concerns regarding the ability to extrapolate data from traditional brachytherapy (BT) to EBT.¹¹ It is recommended that prospective studies with mature follow up be performed to provide a better understanding of the outcomes as well as acute and chronic toxicity profiles with EBT.¹¹ NCCN^® notes that there is insufficient long-term efficacy and safety data to support the routine use of EBT for SCC and BCC.^4,5 Nestor et al. reports there are significant differences between SRT and other energy-based therapies, but SRT is superior to EBT for treating most cases of NMSC.¹²

Evidence Based Guidelines for Image Guidance (IG)

More recently, HRUS has been used as an adjunct in order to improve the effectiveness of both EBT and SRT. A report suggested using high-frequency ultrasound to assess tumor depth; however, they found only a borderline significant correlation between ultrasound-determined and punch biopsy-determined depth for superficial lesions (p = 0.05007), but no correlation for nodular lesions.¹⁷

Another study reported the use of SRT with HRUS for the treatment of NMSC. According to their report, they suggested that the use of HRUS improves the visualization of the tumor including the depth of the lesion and the lateral configuration of the tumor. The tumor depth was used to correlate with the percentage depth dose (PDD), which determines the selection of energy (50, 70, or 100 kV) delivered, and adjustments can be made during the treatment. In their retrospective chart review, 1,243 patients with 1,899 NMSC lesions were treated with the combination of SRT with HRUS. Included in the review, were patients with BCC, SCC and SCCIS. Board-certified radiation therapists administered IGSRT technology to treat lesions with energies ranging from 50, 70 or 100 kV, which was delivered 2–4 times weekly. The mean total number of fractions was 20.2 (SD ±0.90), ranging from 20 to 30. The mean total treatment dose was 5364.4 centigray (cGy) (SD±241.60), ranging from 4453.4 to 6703.2 cGy. The majority of these lesions were treated for 7.5 weeks and followed for a mean of 65.5 weeks (SD±66.70). The duration of follow-up was calculated as the date of last follow-up minus the last treatment date plus 1 day. A HRUS simulation was performed to establish the field and determine the lesion for proper selection prior to treatment. According to the authors, the visualization is necessary to determine tumor breadth and depth for width, energy and dose selection. Thereafter, HRUS was performed during each treatment and after completion in order to make real-time modifications and assess for treatment response, respectively. Energy selection and dose adjustments were contingent upon tumor characteristics seen clinically and on ultrasound (histology and depth). One hundred and seventy-six lesions (9.9% [176/1779]) were treated with a combination of 2 or more energies as a result of adjustments made clinically and on ultrasound. Absolute lesion control was achieved in 99.7% of the patients after an average of 7.5 weeks of treatment, with a stable control rate of 99.6% when the follow-up duration was over 12 months. 95% of lesions with toxicity scoring received a Radiation Treatment Oncology Group Toxicity (RTOG) score of 1 or 2.^15,19

This study noted above has many significant limitations including potential patient selection bias and a nonrandomized, retrospective chart review from 2016 through 2022 which did not identify any underlying tumor characteristics except for the size of the lesion. There was no description of the morphology of the tumor, frequent fractionation regimen changes during the retrospective review and no documentation of the actual HRUS findings to demonstrate the necessity for the additional IG component of the treatment beyond clinical judgment. Also, due to the relatively short follow up period including a mean of 65.5 weeks and a median of 42.29 weeks, longer follow-up would be required to detect recurrence rates for meaningful comparisons to surgical techniques or current SRT treatment regimens. Since different fractionation and energy treatments were selected, it would be difficult to accurately assess the additional need for HRUS. Furthermore, the size of the lesions is relatively small with the majority having a mean diameter of 1.3cm. In this study, there is no mention or comparison as to the necessity of using HRUS to the SRT or how this technology resulted in a greater control rate than SRT alone for different sized lesions with the majority being less than 2 cm. In addition, all the treatments were administered by board-certified radiation oncologists as opposed to dermatologists. The focus of the retrospective, non-randomized study was finding the ideal fractionation and radiation treatment regimen as there is no mention in the paper of how HRUS improved the patient outcomes. Specifically, what was seen that required more than clinical judgement is not differentiated in the paper. Energy selection and dose adjustments were contingent upon tumor characteristics seen clinically and on ultrasound (histology and depth). There is no basis for the conclusion from the authors that the dosing regimen employed, along with the use of HRUS guidance, allow for achieving outstanding local control. There is no way to extrapolate that conclusion based upon the retrospective chart review and changing dosing regimen during the study period.

A retrospective cohort study that compared the 2-year recurrence probability of early stage NMSCs treated by IGSRT for 2,286 lesions to data on NMSCS for 5,391 lesions via on sample proportion testing was performed. Seventeen studies were looked at for MMS and 3 studies were used for comparison. They found that IGSRT-treated NMSCs have a statistically significantly improved 2-year recurrence probability than those treated by MMS, P < 0.001 for pooled data. However, there are very significant limitations of the study including case cohort bias for the studies used, lack of correlation between the early lesions treated with IGSRT versus all the lesions that are typically sent for MMS including recurrent tumors, aggressive histology, and using pooled recurrence rates from MMS without matching tumor types, sizes, histology sub-type and location. In fact, the authors recognized the severe limitation of the study and therefore no extrapolation to the added use of IG to SRT is based upon any true scientific comparisons. Also, there is no mention of what time period the data was collected for the lesions treated with IGSRT. Beyond histology, cohort matching was unable to be performed due to missing data (e.g., tumor size, stage) in comparison papers. The lack of comprehensive cohort matching increases the possibility that confounding factors are impacting the statistical analysis. It is a common end point in evaluating treatment efficacy of BCCs and SCCs long term recurrence rates; however, more time must pass before a 5-year analysis can be done since IGSRT is a relatively new treatment. To compare historical MMS with IGSRT is not a scientific comparison since MMS typically treats more aggressive, larger and higher risk NMSCs and the IGSRT was used to treat less aggressive, smaller and lower risk NMSCs without delineation of histological subtypes.¹⁸

In another study, Yu et al. performed a meta-analysis where they compared 2 recent IGSRT studies to 4 studies identified in the ASTRO literature review using non-image guided external beam therapy (XRT) and SRT. They found in all NMSC histology types a statistically superior outcome for US-SRT compared to XRT/SRT was observed with p-values ranging from p < 0.0001 to p = 0.0438. According to the authors, the 4 XRT/SRT articles were recent, high-quality with large sample sizes, and distilled from a previous ASTRO literature review. Only 4 studies utilizing XRT/SRT were included as the authors attempted to compare “apples to apples”.¹⁹ However, the SRT and XRT studies were at a minimum 10 years older than the current IGSRT studies using newer SRT technology and therefore it is not a like comparison. In fact, the XRT studies included in their comparison were from 1990 and 2001 and the only recent SRT study was from Cognetta et al. in 2012.²⁷ The current SRT technology has dramatically improved and even in some of the more recent studies in SRT the recurrence rates are extremely low. The more recent recurrence rates for SRT are in the range of 1-2%. More limitations of the study include possible overlapping patients in 2 of the 4 studies used for comparison and the different length of follow-up in each of the studies, as well as the lack of tumor characteristics that were treated including the size and location of the tumor and the histology sub-type. Therefore, the level of evidence of this study is of low quality for comparison purposes.

In 1 last study for IGSRT, a retrospective medical record review from 2017 through 2020 was performed for 1,632 patients who underwent treatment with IGSRT for 2,917 NMSC invasive and in situ lesions. It was reported that the SRT, guided by pre-treatment ultrasound imaging to adjust radiation energy and dose, combined with a fractionation treatment schedule of 20 or more treatment fractions, was safe and well tolerated. Of 2,917 NMSC lesions treated, local tumor control was achieved in 2,897 lesions, representing a 99.3% rate of control. Follow-up was for a mean period of 69.8 weeks with a range of 0-220.9 weeks. In this review, the lesion size median for both BCC and SCC was less than previous studies ranging from 0.9 cm to 1.2 cm. Among 1,632 patients, 1,612 patients (98.8%) did not have evidence of disease at their last follow-up visit, and 20 patients (1.2%) had evidence of disease at their last follow-up visit. Limitations of the ultrasound include that it cannot detect tumor deeper than 6 mm (though tumors invading beyond this depth are contraindicated for treatment with IGSRT). Additionally, ultrasound imaging is difficult to attain if the surface is irregular or actively bleeding, which does not allow adequate contact of the probe with the skin. The authors concluded that further study is warranted to evaluate the impact of pre-treatment ultrasound imaging on SRT efficacy. Limitations of this study include selection bias, lack of histology subtypes, small size of the NMSCs treated and what impact, if any, HRUS had on the outcomes other than for pre-treatment patient selection. In fact, there is no mention in the article of how the HRUS was used to change any energy settings beyond clinical evaluation of the patient.¹⁴

Analysis of Evidence (Rationale for Determination)

The overall quality of evidence for the use of SRT for the primary treatment of BCC and SCC in adults is low due to the lack of nonrandomized, single-center study design with very high potential for patient selection bias, variation in SRT techniques across studies and direct comparison to the standard of care, MMS or other established treatments. However, the retrospective evidence tends to support similar outcomes for low-risk lesions not amenable to surgery and similarly some high risk NMSCs with less aggressive histology and smaller tumor sizes. With the newer modalities and recommendations by the various societies including recommendations by NCCN^®, the use of SRT for selected patients is deemed appropriate for nonsurgical candidates.

However, based upon the recommendations of the AAD, ASTRO, NCCN^® and ABS, there is insufficient evidence at this time to justify the use of EBT for the treatment of NMSCs and is not deemed reasonable and necessary for coverage. Moreover, the NCCN^® guidelines and the ABS specifically state that the use of EBT is not justified at this time and should not be used for the treatment of NMSC.

Finally, from the retrospective studies cited above, there is no evidence to support that the addition of HRUS to SRT is required for the treatment of low-risk BCC or low-risk SCC. Comparing IGSRT with prior older technology SRT does not provide additional meaningful comparisons since newer technology machines for delivering SRT have different energy settings and more recent published data with SRT shows nearly equivalent recurrence rates with longer periods of follow-up.^12,13,24,27 In addition, when comparisons were made to the SRT studies without HRUS, no corrections were made for the fact that the SRT studies without HRUS had also included more aggressive lesions and histological subtypes and often larger cutaneous tumors. The smaller more favorable lesions were more preponderant in the retrospective IGSRT studies that were published. Therefore, the quality of evidence is low to support the continued use of HRUS currently for each fractionated treatment.