(P017) Prolonged Progression-Free Survival for Surgically Managed P16-Negative Squamous Cell Carcinoma of the Oropharynx

Eva M. Suarez, MD, Anand Sharma, MD, Kent Armeson, MS, Terry Day, MD; Medical University of South Carolina

Purpose: It is well known that survival of patients with p16-negative oropharyngeal squamous cell carcinoma has a poor prognosis with standard chemoradiation. Studies have not compared the addition of surgery to chemoradiation as a method to improve survival. This study was designed to assess the benefit in progression-free survival (PFS) based on p16 status when surgery is included as part of the treatment paradigm for patients with squamous cell carcinoma of the oropharynx.

Methods: A single-institution retrospective analysis identified 120 patients who were treated for stage III or IV oropharynx squamous cell carcinoma that was tested for p16 overexpression. Patients either received surgery followed by postoperative radiation or chemoradiation, as indicated by final pathology (S + RT/CRT), or definitive chemoradiation (CRT). PFS, defined as the time from the completion from treatment until the first evidence of local or distant recurrence, was summarized and plotted using Kaplan-Meier methods. The log-rank test was used to compare survival distributions across treatment groups, with P < .05 indicating statistical significance.

Results: The median follow-up was 19 months. A total of 32 patients tested negative and 88 tested positive for p16 overexpression. In the p16-negative group, 10 were treated with S + RT/CRT and 22 had definitive CRT. In the p16-positive group, 37 patients were treated with S + RT/CRT and 51 had definitive CRT. In the p16-negative group, 62.5% of patients had recurrence of disease (3 in S + RT/CRT arm and 17 in CRT arm) compared with 15.9% in the p16-positive group (5 in S + RT/CRT arm and 9 in CRT arm). PFS for the p16-negative patients was statistically better for the S + RT/CRT group (mean PFS, 24.7 mo) versus CRT (mean PFS, 21.1 mo) (P = .031). Two-year PFS for the S + RT/CRT arm and CRT arm was 68.6% and 22%, respectively. This difference was not seen in the p16-positive population (mean PFS 46.8 mo for S + RT/CRT vs 36.0 mo for CRT; P = .440). Two-year PFS for the S + RT/CRT arm and CRT arm was 94.6% and 79.7%, respectively. There was no statistical difference in overall survival (OS) among the S + RT/CRT arm and CRT arm within the p16-negative group or the p16-positive group.

Conclusion: Surgery followed by RT or CRT improved PFS for patients with p16-negative oropharynx squamous cell carcinoma compared with those who received definitive chemoradiation. A prospective clinical trial is warranted and is in development to further assess treatment options in this group of patients.