Impact of Mohs Micrographic Surgery on Tumor Staging of Cutaneous Squamous Cell Carcinoma: A Comparison of the 7th and 8th Editions of the American Joint Committee on Cancer Guidelines

BACKGROUND Based on current AJCC-7 guidelines for staging cutaneous squamous cell carcinoma (cSCC), patients with T2 tumor staging represent a prognostically heterogeneous group. The new AJCC-8 guidelines seek to provide improved stratification by inclusion of independent risk factors in the T3 category. These features may be identified in tissue stages during Mohs micrographic surgery (MMS). Thus, low-risk cSCC may be upstaged after MMS, impacting prognosis, additional evaluation, and adjuvant nonsurgical treatment. OBJECTIVE To examine the impact of MMS on cSCC staging under AJCC-7 and AJCC-8 guidelines. MATERIALS AND METHODS The medical record was queried for patients who underwent MMS for cSCC. Data were recorded for 190 MMS specimens and corresponding biopsies. Tumor staging according to AJCC-7 and AJCC-8 was assigned. RESULTS High-risk histologic features are more likely identified with MMS than biopsies. Cutaneous squamous cell carcinoma was equally likely to be upstaged during MMS under both AJCC-7 and AJCC-8, with 10.5% being classified as AJCC-8 T3. Seventy percent of these were only classified as T3 after MMS. Upstaging to T3 during MMS under AJCC-8 is less likely than upstaging to T2 under AJCC-7. CONCLUSION Mohs surgeons have a significant impact on accurate staging of high-risk cSCC. AJCC-8 improves risk stratification of cSCC. Address correspondence and reprint requests to: Kiran Motaparthi, MD, Department of Dermatology, University of Florida College of Medicine, 4037 NW 86th Terrace, 4th Floor, Room 4119 Springhill, Gainesville, FL 32606, or email: kmotaparthi@dermatology.med.ufl.edu Supported by the National Center For Advancing Translational Sciences of the National Institutes of Health under Award Number UL1TR001427. The authors have indicated no significant interest with commercial supporters. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. © 2018 by the American Society for Dermatologic Surgery, Inc. Published by Wolters Kluwer Health, Inc. All rights reserved.

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