Local control in resectable and borderline resectable pancreatic cancer (PCa) treated with preoperative chemoradiation using IMRT or chemotherapy alone.

Abstract

282 Background: The primary objective is to review local control and failure patterns in PCa patients treated with preoperative chemoradiation (chemoXRT) using IMRT compared to patients treated with chemotherapy alone. Methods: All patients with resectable and borderline resectable PCa treated between 1/1/2009 -11/1/2011 were reviewed. During the study period, 68 patients (40 borderline resectable, 28 resectable) were treated with preoperative chemoXRT (50.4 Gy [1.8 Gy/fx] with concurrent gemcitabine [n=59] or capecitabine [n=7]). 12 patients with resectable tumors received gemcitabine based chemotherapy alone and did not receive radiation therapy due to enrollment on chemotherapy only protocols (n=10) or to patient preference (n=2). Radiation was delivered to a CTV that includes the primary mass, the SMA and SMV, +/- the celiac axis. A 4D-CT and daily image guidance were used in all patients. The local failure free interval was defined as the time from surgical resection to local failure or last documented CT scan of the abdomen with no evidence of local disease progression. Results: Following preoperative chemoXRT, 48/68 patients underwent resection with 47(98%) R0 resections. 11/12 patients in the No XRT group undwerent resection with 10 (91%) R0 resections. In the No XRT group, 8/11 (73%) patients failed locally at the SMA/SMV or resection bed as a component of first failure compared to 1/48 (2%) patients who received preoperative chemoXRT (p<0.001). Local failure was the sole site of first failure in 5/11 patients in the No XRT group and 0/48 patients who received preoperative chemoXRT. The actuarial rate of local failure 1 year from surgery was 5% in the preoperative chemoXRT group vs 27% in the No XRT group (p<0.001). All local failures in the No XRT group would have been encompassed using the CTV target volumes used in patients treated with preoperative chemoXRT. Conclusions: IMRT-based, conformal, preoperative chemoXRT for resectable and borderline resectable PCa may facilitate margin negative resection and increase local control. Omission of radiation therapy may result in high rates of local failures at the SMA/SMV vasculature or in the pancreatic bed.