Image-Guided Superficial Radiation Therapy Has Superior 2-Year Recurrence Rates to Mohs Micrographic Surgery

Abstract

Non-melanoma skin cancers (NMSCs) are the most common malignancy in the USA, and incidence is rising. Mohs micrographic surgery (MMS) is a tissue-sparing surgical technique often used in NMSCs. Superficial radiation therapy (SRT) was widely used prior to the advent of MMS, but MMS has superior recurrence rates and replaced SRT as a first-line therapy. Image-guided SRT (IGSRT) was invented in 2015 and utilizes ultrasound to improve SRT precision and produces minimal side effects (99% grade 1 or 2).[1] The hypothesis is that NMSCs treated with IGSRT will have improved 2-year recurrence rates of compared to those treated with Mohs micrographic surgery. This retrospective cohort study compared the 2-year recurrence probability of early stage NMSCs (squamous and basal cell carcinomas (SCCs and BCCs)) treated by IGSRT (2,286 lesions) to data on NMSCs treated by MMS (5,391 lesions) via one sample proportion tests. IGSRT-treated NMSC data is from a database published by Yu et al.[1] The 2-year recurrence probability statistical analysis is from McClure et al.[2] Medical Subject Headings were used to search PubMed for reports of 2-year recurrence rates of NMSCs treated by MMS. Seventeen studies were screened; 14 studies were excluded for lack of 2-year time to event analysis, or irrelevant patient population (non-BCC/SCC study, advanced disease), leaving 3 studies for comparison. IGSRT-treated NMSCs have a statistically significantly improved 2-year recurrence rates compared to MMS-treated (p<0.001 for pooled data). When separated by histology, 2-year recurrence rates of all reported SCCs and BCCs treated by MMS were also inferior to those treated by IGSRT, p<0.001, p = 0.0218, respectively. In this analysis, IGSRT has superior 2-year recurrence rates. Limitations include insufficient follow-up to report on the 5-year recurrence probability and inability to adjust for confounding factors beyond histology. This data implies that IGSRT is a well-tolerated, paradigm-shifting treatment option for patients with early stage NMSCs who cannot tolerate or refuse surgery. IGSRT provides patients the choice of treatment modality that best aligns with their goals of care.