Comparative effectiveness of induction chemotherapy for oropharyngeal squamous cell carcinoma: A population-based analysis

Objectives: Despite several randomized trials, the optimal chemotherapy paradigm for locally advanced oropharyngeal carcinoma (OPSCC) is controversial. This population-based analysis assessed the overall survival (OS) benefit of induction chemotherapy (IC) for patients with stage III-IVB OPSCC.

Materials and methods: Patients in the National Cancer Database with stage III-IVA-B OPSCC treated with curative-dose radiotherapy and IC or concurrent chemotherapy (CRT) between 2003 and 2011 were eligible. The primary outcome was OS, and secondary endpoints included OS for high-risk (T4 and/or N3 disease) and human papillomavirus (HPV) subsets.

Results: Of the 14,856 analyzed patients, 78% and 22% received CRT and IC, respectively. With a median follow-up for surviving patients of 44 months, the 5-year OS probability for the entire cohort was 66% (66% CRT vs. 64% IC, p=0.022). Multivariable survival analysis showed no significant difference between CRT and IC (hazard ratio, HR, 0.95 for IC, p=0.255), and sensitivity analyses to adjust for immortal time bias brought the HR to 1.0 (p=0.859). There was also no OS difference for high-risk patients. There was a trend in favor of CRT for HPV-positive OPSCC (HR 1.63 with IC, p=0.064), with a significant OS benefit for HPV-negative, high-risk OPSCC (HR 0.63, p=0.048).

Conclusion: For the vast majority of patients, including HPV-positive individuals, there was no difference in OS with IC, arguing for CRT to remain as the standard therapy. Subset analysis revealed a small cohort of aggressive cancer (T4/N3 HPV-negative) which may benefit from from IC, although selection bias could not be ruled out.