Variability in Outcome Based on Type of Concurrent Chemotherapy for Treatment of Squamous Cell Carcinoma of the Oropharynx

Abstract

Purpose/Objective(s): Concurrent carboplatin and taxol (C/T) is commonly utilized in the management of head and neck squamous cell carcinoma (HNSCC) based on phase 2 data. At our institution we underwent a shift in practice over a relatively short period of time from frequent use of concurrent C/T to predominantly cisplatin (Cis)-based concurrent therapy. We sought to determine cancer-specific outcomes with Cis-based versus C/T concurrent therapy. Materials/Methods: We retrospectively analyzed 336 consecutive patients (pts) with oropharyngeal HNSCC treated at a single institution with definitive intensity modulated radiation therapy to a median dose of 70 Gy (median 2 Gy/fraction) using predominantly a dose-painting technique. Univariable and multivariable Cox proportional hazard regression models were used to evaluate the association of concurrent chemotherapy-type with overall survival (OS), recurrence-free survival (RFS), local-recurrence failure (LRF), and distant metastasis (DM). The multivariable model included clinical predictors that were significant in the univariate model for survival outcomes with a P value .05. The Fine & Gray method was used to adjust for competing risks. Results: The cohort comprised 336 pts, mostly male (85%), with a median age of 57.3 years. The most common sites were tonsil (49.4%) and base of tongue (46.7%). The American Joint Committee on Cancer stage was I (0.3%), II (3.9%), III (1.1%), IVA (71.5%), and IVB (9.2%). Most pts were human papillomavirus (HPV)-positive (72.3%), 13.1% were HPV-negative, and 14.6% had unknown HPV status. Pts received upfront concurrent chemoradiation (58%) or sequential therapy (38.4%); 3.6% received radiation and no chemotherapy. Eighty pts (23.8%) received Cis-based concurrent chemotherapy, and 103 pts (30.7%) received weekly C/T concurrent chemotherapy. With a median follow-up of 3.8 years, the 3-year OS was 89.3% with CI of LRF of 9.6% and CI of DM of 9.1%. Compared with Cis-based concurrent chemotherapy, pts that received weekly C/T had worse OS (hazard ratio [HR] 6.57; 95% confidence interval [CI] 1.54-28.0) and RFS (HR 3.38; 95% CI 1.29-8.87) and higher rates of LRF (HR 9.42; 95% CI 1.26-70.5). The significantly worse OS seen with C/T concurrent chemotherapy remained statistically significant after adjusting for stage, HPV status, and initial comorbidities (HR 5.00; 95% CI 1.15-21.79) and after restricting the analysis to the 207 pts that received concurrent chemotherapy without induction (HR 8.88; 95% CI 1.56-68.23). Conclusion: Concurrent carboplatin and taxol was associated with worse OS and cancer-specific outcomes following definitive radiation-based therapy for SCC of the oropharynx. Cisplatin-based therapy should continue to be the concurrent therapy of choice for oropharyngeal SCC.