Background: Though the National Comprehensive Cancer Network recommends consideration of localized adjuvant radiation after clear-margin surgery for cutaneous squamous cell carcinoma (cSCC) with large-caliber (≥0.1-mm) nerve invasion (LCNI) and other high-risk features, only a single small study has compared surgery plus adjuvant radiation therapy (S+ART) to surgical monotherapy (SM) for cSCC.
Objective: Compare S+ART to SM for primary cSCCs with LCNI and other risk factors.
Methods: Matched retrospective cohort study of primary cSCCs (matched on sex, age, immune status, type of surgery, diameter, differentiation, depth, and LCNI) treated with S+ART versus SM. A subgroup analysis of cSCCs with LCNI was performed.
Results: In total, 62 cSCCs were included in matched analysis (31 S+ART and 31 SM) and 33 cSCCs in the LCNI analysis (16 S+ART and 17 SM). There were no significant differences in local recurrence, metastasis, or death from disease in either analysis. Risk of local recurrence was low (8%, 7/89), with 3 of the local recurrences being effectively treated upon recurrence.
Limitations: Single academic center and nonrandomized design.
Conclusion: Adjuvant radiation did not improve outcomes compared with SM due to a low baseline risk of recurrence, although adjuvant radiation for named nerve invasion and LCNI of ≥3 nerves has been shown to improve outcomes in a prior study. Randomized studies are needed to define the subset of cSCC for whom adjuvant radiation has utility.
Keywords: Mohs micrographic surgery; adjuvant therapy; cutaneous squamous cell carcinoma; nonmelanoma skin cancer; perineural invasion; radiation therapy.
Copyright © 2019 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.