Outcomes of P16 positive oropharyngeal squamous cell carcinoma treated with surgery and adjuvant IMRT

Objectives This study compares the outcomes of patients with p16+ oropharyngeal squamous cell carcinoma (OPSCC) treated with surgery followed by adjuvant radiotherapy (aRT) or chemoradiotherapy (aCRT). Methods From1997 to 2009, of 376 patients with OPSCC, 97 were p16+ and eligible: 51 received aRT and 46 received aCRT. Univariate and multivariate Cox regression, and propensity score analyses were performed. Results The 5-year locoregional failure (LRF) and distant metastases (DM) rates for the aRT and aCRT groups were 4 versus 0 % and 10 versus 9 %, respectively. The following were associated with a worse OS and DFS on multivariate analysis: pathologic T3/T4 stage (OS p=0.03; DFS p=0.02), age =55 years (OS p=0.02; DFS p=0.01), and a smoking history (OS p=0.02; DFS p=0.04). In multivariate and propensity score analyses, aCRT did not have a significant effect on OS, DFS, and DMFS. Conclusions In this retrospective study of postoperative p16+, stage III-IVb OPSCC patients receiving aRT or aCRT, we did not find a benefit in OS, DFS, or DMFS with the addition of chemotherapy to IMRT. Given the predominantDMfailure pattern in this surgical series, novel systemic strategies are needed. These data warrant further study.