Harris BN, et al. - Authors retrospectively investigated 349 subjects to evaluate the indications for adjuvant radiation therapy in cases with cutaneous squamous cell carcinoma (CSCC), a most common malignant tumor worldwide from January 1, 2008, to June 30, 2016. They observed an association between the receipt of adjuvant radiation therapy with the improved survival in cases with perineural invasion (PNI) and regional disease.

Methods

• Authors analyzed retrospectively 349 subjects with head and neck CSCC treated with primary resection with or without adjuvant radiation therapy at 2 tertiary referral centers from January 1, 2008, to June 30, 2016.
• They compared the data between treatment groups with a χ² analysis.
• They estimated disease-free survival (DFS) and overall survival (OS) were by using a Kaplan-Meier survival analysis with log-rank test and a Cox proportional hazards multivariate regression.

Results

• A sum of 349 patients with tumors met the inclusion criteria (mean [SD] age, 70 [12] years; age range, 32-94 years; 302 [86.5%] male), and 191 (54.7%) were given adjuvant radiation therapy.
• They estimated 5-year Kaplan-Meier analysis as 59.4% for DFS and 47.4% for OS.
• Younger immunosuppressed participants and candidates with larger, regionally metastatic, poorly differentiated tumors with perineural invasion (PNI) were more likely to receive adjuvant radiation therapy.
• Lower DFS was observed for cases with periorbital tumors (hazard ratio [HR], 2.48; 95% CI, 1.00-6.16), PNI (HR, 1.90; 95% CI, 1.12-3.19), or N2 or greater nodal disease (HR, 2.16; 95% CI, 1.13-4.16) on Cox proportional hazards multivariate regression,.
• Participants with N2 or greater nodal disease (HR, 2.43; 95% CI, 1.42-4.17) and immunosuppressed patients (HR, 2.17; 95% CI, 1.12-4.17) had lower OS.
• They also found adjuvant radiation therapy correlated to improved OS for the entire cohort (HR, 0.59; 95% CI, 0.38-0.90).
• Adjuvant radiation therapy was observed associated with improved DFS (HR, 0.47; 95% CI, 0.23-0.93) and OS (HR, 0.44; 95% CI, 0.24-0.86) in subset analysis of tumors with PNI.
• They also noted adjuvant radiation therapy associated with improved DFS (HR, 0.36; 95% CI, 0.15-0.84) and OS (HR, 0.30; 95% CI, 0.15-0.61) in participants with regional disease.