Benefit From Adjuvant Radiation Therapy In Oropharyngeal Cancer Patients That Underwent Induction Chemotherapy Plus Surgery

Abstract

This retrospective study aims to evaluate the outcome of patients with tonsil squamous cell carcinoma (SCC) treated with induction chemotherapy (ICT) followed by surgery, with or without external beam radiation therapy (EBRT), to assess the impact of EBRT regarding human papillomavirus (HPV) status. Between 1997 and 2017, 99 patients with tonsil SCC underwent ICT followed by surgical resection. After surgery, 79 patients had adjuvant EBRT (Group 1), while 16 patients (free margins, N0 or N1) have not received radiotherapy EBRT (Group 2). Median follow-up was 71 months. HPV status was positive in 42 patients (43%), negative in 50 patients (57%). After ICT, pathological complete response (CR) was reported for the primary site or lymph nodes in 25 patients (27%) and 53 patients (58%) respectively. HPV-positive status was the only prognosis factor associated with improved CR after ICT (p = 0.04). Five-year progression-free survival (PFS) in this cohort, group 1 and group 2 were 68% (IC95% = 59 – 79), 72/% (IC95% = 62 – 83), and 54% (IC95% = 36 – 81) respectively (p = 0.04). In multivariate analysis, prognosis factors associated with improved PFS were: primary and nodal CR after ICT (p < 0.001), EBRT (p < 0.001), and HPV-positive status (p = 0.02). Five-years OS in this cohort, group 1 and group 2 were 69% (IC95% = 61 – 80), 64% (IC95% = 54 – 76), and 90% (IC95% = 78 – 100) respectively (p = 0.7). In multivariate analysis, the only prognosis factor related with a longer OS was pN0 status after ICT (p < 0.001). In this series, HPV-positive status was associated with improved CR rates after ICT. Still, PFS was decreased in patients that did not underwent radiation therapy after ICT plus surgery, independently from HPV-status or response after ICT.