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Original Investigation
December 20, 2018

Association of Adjuvant Radiation Therapy With Survival in Patients With Advanced Cutaneous Squamous Cell Carcinoma of the Head and Neck

Author Affiliations
  • 1Department of Otolaryngology, University of California, Davis, Sacramento
  • 2Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
  • 3Department of Radiation Oncology, University of California, Davis, Sacramento
JAMA Otolaryngol Head Neck Surg. Published online December 20, 2018. doi:10.1001/jamaoto.2018.3650
Key Points

Question  Is there an association between adjuvant radiation therapy and survival in patients with advanced cutaneous squamous cell carcinoma, and which patients benefit the most from addition of adjuvant therapy to surgical treatment?

Findings  In this multi-institutional study of 349 patients with advanced cutaneous squamous cell carcinoma, adjuvant radiation therapy was associated with improved disease-free survival and overall survival in patients with perineural invasion and regional adenopathy.

Meaning  The findings suggest that patients with perineural invasion and regional disease benefit the most from addition of adjuvant radiation therapy to surgical treatment.

Abstract

Importance  Cutaneous squamous cell carcinoma (CSCC) is one of the most common malignant tumors worldwide. There is conflicting evidence regarding the indications for and benefits of adjuvant radiation therapy for advanced CSCC tumors of the head and neck.

Objective  To assess indications for adjuvant radiation therapy in patients with CSCC.

Design, Setting, and Participants  Retrospective analysis of 349 patients 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.

Main Outcomes and Measures  Data were compared between treatment groups with a χ2 analysis. Disease-free survival (DFS) and overall survival (OS) were analyzed using a Kaplan-Meier survival analysis with log-rank test and a Cox proportional hazards multivariate regression.

Results  A total of 349 patients had tumors that met the inclusion criteria (mean [SD] age, 70 [12] years; age range, 32-94 years; 302 [86.5%] male), and 191 (54.7%) received adjuvant radiation therapy. The 5-year Kaplan-Meier estimates were 59.4% for DFS and 47.4% for OS. Patients with larger, regionally metastatic, poorly differentiated tumors with perineural invasion (PNI) and younger immunosuppressed patients were more likely to receive adjuvant radiation therapy. On Cox proportional hazards multivariate regression, patients 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) had lower DFS. Immunosuppressed patients (HR, 2.17; 95% CI, 1.12-4.17) and those with N2 or greater nodal disease (HR, 2.43; 95% CI, 1.42-4.17) had lower OS. Adjuvant radiation therapy was associated with improved OS for the entire cohort (HR, 0.59; 95% CI, 0.38-0.90). In a subset analysis of tumors with PNI, adjuvant radiation therapy was associated with improved DFS (HR, 0.47; 95% CI, 0.23-0.93) and OS (HR, 0.44; 95% CI, 0.24-0.86). Adjuvant radiation therapy was also 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 patients with regional disease.

Conclusions and Relevance  Among patients with advanced CSCC, receipt of adjuvant radiation therapy was associated with improved survival in those with PNI and regional disease.

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