Skin Cancer

Superficial Radiation Therapy (SRT)

SRT for treatment of Skin Cancer Lesions

Source: American College of Mohs Surgery (ACMS)

Non-melanoma skin cancer is the most common malignancy in the United States. Surgical management continues to be the gold standard treatment for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), with Mohs micrographic surgery (MMS) serving as the first-line treatment for BCCs and SCCs in cosmetically sensitive areas and for high-risk tumors.

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What is superficial radiation therapy (SRT)? 

Superficial radiation therapy (SRT) is an X-ray based treatment that requires multiple patient visits for treatment of skin cancers. SRT has recently been highly promoted by companies that sell and profit from SRT devices and equipment. SRT is different from brachytherapy. Brachytherapy uses ionizing radiation for treatment, requiring different treatment planning and different billing codes than SRT. Brachytherapy is used for many types of cancer, including BCC and SCC.

How does SRT compare to Mohs micrographic surgery? 

SRT has inferior long-term cure rates compared to Mohs surgery, requires multiple treatment visits, is higher cost, and has limited published literature on its side effects. According to national expert consensus entities, SRT should only be considered as a second-line treatment option under special circumstances for patients who are non-surgical candidates. 

Mohs Surgery versus Image-Guided Superficial Radiation Therapy

Mohs SRT
Mohs only removes the skin cancer, preserving healthy skin Radiation damages everything in its path, including healthy skin
100% of the skin is evaluated to ensure complete cancer removal There is no confirmation that the cancer has been removed
Gold standard treatment for most skin cancers, even aggressive ones Not recommended as a first or even second- line treatment option by national cancer guidelines
Cancer is cured in a single visit Requires 15 to 20 treatments over several days to weeks
CURES skin cancer Can cause more skin cancers
Over 99% cure rate At least 1 in 20 will come back
Wound is repaired same day Skin irritation, blistering, peeling, color change, hair loss, tooth decay, and damage to salivary glands are common side effects
Superior long-term cosmetic outcome Unpredictable long- term cosmetic outcome
Cost effective Very expensive
Efficacy and Patient Burden SRT Mohs
Number of Visits to Complete Treatment* 5-30 1-2
Published Recurrence Rates for Primary BCC** 4.2 - 15.8% 1.0 - 2.5%
Published Recurrence Rates for cSCC** 5.8 - 10.7% 2.6 - 3.1%
Published Follow-up Short (1-3 years) Long (5-10 years)
Pathologic Confirmation of Margin Status No (disease control determined by clinical exam +/- ultrasound) Yes (frozen section histology)
Expert Consensus Recommendations SRT Mohs
AAD Position Statement Second-line option when surgery is contraindicated Most effective treatment option with the highest cure rates
NCCN Guidelines Second-line option for non-surgical candidates First-line treatment for high-risk BCC and low-, high- and very-high risk cSCC risk
Scope of Practice / Level of Training*** SRT Mohs
Residency Curriculum Requirement No Yes
Fellowship Training Available/Encouraged No Yes
Board Certification*** No Yes

*Depending on a pre-op evaluation
**5-year relapse free survival rate
***Current board certification for MMS requires a minimum number of cases and/or fellowship training 

Published Cure Rates: Mohs surgery has a higher cure rate, with a higher level of supporting evidence 

  • Higher local recurrence (LR) rate with SRT
  • Primary BCC
  • 5-year LR: MMS 1.0-2.5%1-4 vs. SRT 4.2-15.8%5-7
  • 10-year LR: MMS 4.4%8 vs. SRT no data
  • Recurrent BCC
  • 5-year LR: MMS 2.4-4%1,2 vs. SRT no data
  • Primary SCC
  • 5-year LR: MMS 2.6-3.1%9,10 vs. SRT 5.8-10.7%5,6,11
  • 10-year LR: MMS no data vs. SRT 19.6%11
  • Recurrent SCC
  • 5-year LR: MMS 5.9%9 vs. SRT no data
  • Lower quality of supporting evidence for SRT
  • Cure rate based on histological confirmation (gold standard) for MMS vs. “disease control” (i.e. clinical exam or ultrasound) for SRT12
  • Multiple 5 and 10-year follow up studies for MMS with low local recurrence rates1-4,8-10
  • Several SRT papers are written by consultants of SRT companies, and many of these only publish short-term results (1-3 years)5,12-15
  • Published results with SRT vary widely, with some longer term studies showing high local recurrence rates7,11
  • Secondary cancers have a latency of onset of 10 years or longer after radiation therapy — published literature does not include greater than 10-year follow up after current SRT dosing regimens, therefore, long-term sequelae of SRT are unknown or unpublished 

Patient Burden: SRT poses a high time and cost burden to patients and the healthcare system 

  • SRT requires multiple treatment visits for “disease control” versus one treatment visit for cure with MMS
  • Number of treatment sessions vary widely by SRT provider ranging from 5-30 treatment sessions5,12
  • Some providers regularly administer 20-30 treatment sessions for treatment for every skin cancer treated12
  • With multiple billing codes used with SRT, SRT can impose a significantly higher cost than MMS

Short & Long-term Side Effects:

  • SSRT devices do not require rigorous efficacy and safety studies for specific skin indications with the FDA’s premarket approval pathway
  • Short-term side effects can include pigmentary changes, erythema, and ulceration 6
  • X-ray therapy, especially for acne treatment, has been reported with numerous malignancies, including basal cell carcinoma and breast cancer 16,17
  • MMS has a well-established safety profile 18 

This information is provided for educational and informational purposes only. It is intended to offer ACMS members and their referring providers guiding principles and policies regarding SRT and MMS. It is not intended to establish a legal or medical standard of care. Physicians and non-physician providers should use their personal and professional judgment in interpreting these guidelines and applying them to the particular circumstances of their individual practice arrangements. 

References:
  1. Mosterd K, Krekels GA, Nieman FH, et al. Surgical excision versus Mohs’ micrographic surgery for primary and recurrent basal-cell carcinoma of the face: a prospective randomised controlled trial with 5-years’ follow-up. Lancet Oncol. 2008;9(12):1149-1156. doi:10.1016/S1470-2045(08)70260-2
  2. Paoli J, Daryoni S, Wennberg AM, et al. 5-year recurrence rates of Mohs micrographic surgery for aggressive and recurrent facial basal cell carcinoma. Acta Derm Venereol. 2011;91(6):689-693. doi:10.2340/00015555-1134
  3. Rowe DE, Carroll RJ, Day CL Jr. Long-term recurrence rates in previously untreated (primary) basal cell carcinoma: implications for patient follow-up. J Dermatol Surg Oncol. 1989;15(3):315-328. doi:10.1111/j.1524-4725.1989.tb03166.x
  4. Leibovitch I, Huilgol SC, Selva D, Richards S, Paver R. Basal cell carcinoma treated with Mohs surgery in Australia II. Outcome at 5-year follow-up. J Am Acad Dermatol. 2005;53(3):452-457. doi:10.1016/j.jaad.2005.04.087
  5. Cognetta AB, Howard BM, Heaton HP, Stoddard ER, Hong HG, Green WH. Superficial x-ray in the treatment of basal and squamous cell carcinomas: a viable option in select patients. J Am Acad Dermatol. 2012;67(6):1235-1241. doi:10.1016/j.jaad.2012.06.001
  6. Schulte KW, Lippold A, Auras C, et al. Soft x-ray therapy for cutaneous basal cell and squamous cell carcinomas. J Am Acad Dermatol. 2005;53(6):993-1001. doi:10.1016/j.jaad.2005.07.045
  7. Zagrodnik B, Kempf W, Seifert B, et al. Superficial radiotherapy for patients with basal cell carcinoma: recurrence rates, histologic subtypes, and expression of p53 and Bcl-2. Cancer. 2003;98(12):2708-2714. doi:10.1002/cncr.11798
  8. van Loo E, Mosterd K, Krekels GA, et al. Surgical excision versus Mohs’ micrographic surgery for basal cell carcinoma of the face: A randomised clinical trial with 10 year follow-up. Eur J Cancer. 2014;50(17):3011-3020. doi:10.1016/j.ejca.2014.08.018
  9. Leibovitch I, Huilgol SC, Selva D, Hill D, Richards S, Paver R. Cutaneous squamous cell carcinoma treated with Mohs micrographic surgery in Australia I. Experience over 10 years. J Am Acad Dermatol. 2005;53(2):253-260. doi:10.1016/j.jaad.2005.02.059
  10. Rowe DE, Carroll RJ, Day CL Jr. Prognostic factors for local recurrence, metastasis, and survival rates in squamous cell carcinoma of the skin, ear, and lip. Implications for treatment modality selection. J Am Acad Dermatol. 1992;26(6):976-990. doi:10.1016/0190-9622(92)70144-5
  11. Barysch MJ, Eggmann N, Beyeler M, Panizzon RG, Seifert B, Dummer R. Long-term recurrence rate of large and difficult to treat cutaneous squamous cell carcinomas after superficial radiotherapy. Dermatology. 2012;224(1):59-65. doi:10.1159/000337027
  12. Tran A, Moloney M, Kaczmarski P, et al. Analysis of image-guided superficial radiation therapy (IGSRT) on the treatment of early-stage non-melanoma skin cancer (NMSC) in the outpatient dermatology setting. J Cancer Res Clin Oncol. 2023;149(9):6283-6291. doi:10.1007/s00432-023-04597-2
  13. Yu L, Oh C, Shea CR. The Treatment of Non-Melanoma Skin Cancer with Image-Guided Superficial Radiation Therapy: An Analysis of 2917 Invasive and In Situ Keratinocytic Carcinoma Lesions. Oncol Ther. 2021;9(1):153-166. doi:10.1007/s40487-021-00138-4
  14. Nestor MS, Berman B, Goldberg D, et al. Consensus Guidelines on the Use of Superficial Radiation Therapy for Treating Nonmelanoma Skin Cancers and Keloids [published correction appears in J Clin Aesthet Dermatol. 2019 Jun;12(6):14]. J Clin Aesthet Dermatol. 2019;12(2):12-18.
  15. Roth WI, Shelling M, Fishman K. Superficial Radiation Therapy: A Viable Nonsurgical Option for Treating Basal and Squamous Cell Carcinoma of the Lower Extremities [published correction appears in J Drugs Dermatol. 2019 Apr 01;18(4):398]. J Drugs Dermatol. 2019;18(2):130-134.
  16. El-Gamal H, Bennett RG. Increased breast cancer risk after radiotherapy for acne among women with skin cancer. J Am Acad Dermatol. 2006;55(6):981-989. doi:10.1016/j.jaad.2005.10.005
  17. Karagas MR, McDonald JA, Greenberg ER, et al. Risk of basal cell and squamous cell skin cancers after ionizing radiation therapy. For The Skin Cancer Prevention Study Group. J Natl Cancer Inst. 1996;88(24):1848-1853. doi:10.1093/jnci/88.24.1848
  18. Merritt BG, Lee NY, Brodland DG, Zitelli JA, Cook J. The safety of Mohs surgery: a prospective multicenter cohort study. J Am Acad Dermatol. 2012;67(6):1302-1309. doi:10.1016/j.jaad.2012.05.041 

Source: ACMS (PDF), (PDF)

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