High Risk Head and Neck Cutaneous Squamous Cell Carcinoma Treated With Mohs Surgery or Mohs Surgery and Adjuvant Radiation Therapy

Abstract

<h3>Purpose/Objective(s)</h3> The recurrence risk for head and neck (H&N) cutaneous squamous cell carcinoma (cSCC) is higher than other sites, and current National Cancer Comprehensive Network (NCCN) and American Society of Radiation Oncology (ASTRO) guidelines encourage considering adjuvant radiation therapy (RT) for high-risk patients. Actuarial recurrence rates following R0 Mohs micrographic surgery have to our knowledge not yet been reported for high risk cSCC H&N patients, and we hypothesized that recurrence rates would be low for these patients regardless of the addition of RT. <h3>Materials/Methods</h3> Between 1/2011 and 1/2020, 362 consecutive H&N cSCC tumors in 325 patients underwent R0 Mohs also with eligibility criteria of size > 2 cm, 10 of whom underwent adjuvant RT (median 52.5 Gy/25 fractions & 6 with elective nodal RT). Kaplan-Meier analyses were performed to evaluate recurrence outcomes, and log-rank was used to compare survival distributions of 2 samples with <i>P</i>≤0.05 considered significant. <h3>Results</h3> Median follow-up from Mohs was 33.4 months, and mean pre-operative size was 3.0 cm with scalp the most common site. Median age was 80.0 years, and 3-year overall survival for all patients was 52.2% with only 4 deaths attributable to cSCC. There were 24 cSCC with perineural invasion (PNI), 32 poorly differentiated, 50 with deep invasion defined as > 6 mm or through subcutaneous fat, 72 with immunosuppression, and 109 with high-risk location defined as ear/lip/temple. No patient received adjuvant systemic therapy and none had a distant failure. The hazard ratios and 95% confidence intervals for locoregional recurrence with classic high-risk features were: PNI (2.68; 0.55 – 12.9), deep invasion (3.02; 0.96 – 9.53), poorly differentiated (vs. well/moderately) (2.20; 0.52 – 9.32), immunosuppression (1.36; 0.50 – 3.69), and high-risk location (0.91; 0.39 – 2.14). High risk tumors defined as AJCC T3 (vs. T1-T2) (3.39; 1.49 – 7.75) and BWH classification T2b-T3 (vs. T2a) (3.16; 1.33 – 7.52) had a significantly increased recurrence risk. The Table shows recurrence rates, with only 1 RT patient experiencing an out-of-RT field scalp in-transit metastasis. Of the 25 that recurred, 56% were rendered disease free with salvage therapy. <h3>Conclusion</h3> In the setting of R0 Mohs for high-risk H&N cSCC, although locoregional control was numerically highest in the small group who received adjuvant RT, with the reasonable salvage rate and infrequent cancer-specific deaths routine offering of RT may be unnecessary.