LAUSR

e17571 Background: Squamous cell carcinoma of the head and neck (SCCHN) is currently the sixth most common cancer in the world and is linked to tobacco, alcohol and human papillomavirus (HPV). Cisplatin (Cs)-based concurrent chemoradiation is currently the standard treatment for locally advanced disease with a desire for organ preservation. In 2006, cetuximab (Cx) with radiation was approved as another option for this indication. We performed a single institute retrospective analysis to explore the difference in efficacy between Cs and Cx regimens with respect to P16 and smoking status. Methods: We retrospectively reviewed pts in Loma Linda University Medical Center (LLUMC) with locally advanced SCCHN who received concurrent chemoradiation with either Cx or Cs as first-line treatment from 2006 to present. We excluded patients with nasopharyngeal cancers, and patients having surgery as first line of treatment. Overall survival (OS) and disease free survival (DFS) with respect to p16 status and smoking status are the two primary endpoints. Results: Based on our study criteria, 115 out of 1545 screened pts qualified. The average age at diagnosis was 60 years. 75.7% were males and 24.3% were females. Median follow-up is 26 months. There are overall 55 DFS events and 23 OS events. Comparing between smokers (S, n = 44) and non-smokers (NS, n = 42), there is no significant difference in OS (NS: HR = 0.73 [0.28-1.92], p = 0.52) while the DFS was significantly better in the NS (NS: HR = 0.53 [0.29-0.98], p = 0.043). The overall median OS of the P16-pos pts (n = 49) is not reached while that of P16-neg pts (n = 12) is 36 mo (P16-neg: HR = 6.431 [1.71-24.13], p = 0.0058). The overall median DFS of the P16-pos pts is not reached while that of P16-neg pts is 6.5 mo (P16-neg: HR = 5.39 [2.32-12.54], p < 0.001). Overall, the median OS of Cx is 132 mo while that of Cs is not reached (Cs: HR = 0.38 [0.16-0.90], p = 0.027). The median DFS is 30 mo for Cs and 25 mo for Cx. Within P16-pos population, there are 4 OS events in Cx (n = 18) while 0 in Cs (n = 31)(p = 0.0062, favors Cs); there are 5 DFS events in Cx while 9 in Cs (Cs: HR = 1.17 [0.39-3.51], p = 0.78). The median OS and DFS for both groups are not reached. Conclusions: Our analysis of retrospective single institute data shows that positive P16 significantly associates with better OS. These findings are consistent with previous reports. Compared to Cx, the Cs regimen significantly associates with a better OS but not DFS in both overall and P16-pos populations.