Immediate versus delayed adjuvant chemoradiation for resected pancreatic cancer: An analysis of local control and survival.

Abstract

301 Background: Patients with resected pancreatic cancer have a significant risk of both local and distant failures. Because of the importance of chemotherapy (CT) highlighted by recent trials, the ongoing RTOG 0848 delays chemoradiation (CRT) randomization to after 5 cycles of chemotherapy (CT). However, the impact of delaying CRT on LR is unknown. We evaluated the patterns of failure and outcomes for patients treated with immediate vs. delayed CRT. Methods: 174 consecutive patients with resectable pancreas cancer who received post-operative CRT at the Massachusetts General Hospital and Brigham & Women’s Hospital/Dana-Farber Cancer Institute between 1998-2010 were retrospectively reviewed on an IRB approved protocol. CRT was delivered to 50.4 Gy with concurrent 5FU or capecitabine. Patient baseline characteristics, pathologic features, and CA19-9 were obtained. Patients were divided into immediate CRT vs. delayed CRT, defined as receiving any CT prior to CRT. LR was independently re-reviewed and confirmed. LR, PFS, and OS were calculated using the Kaplan-Meier method and groups compared using the log-rank test. Results: Median age was 62 (range, 34-83), 75 were male, and ECOG PS was 0-1 in 95% of patients. Median tumor size was 3 cm, 67% had positive nodes, and 33% had positive margins. Mean pre-operative and post-operative CA 19-9 was 813 U/mL and 19 U/mL, respectively. 123/174 (72%) patients received immediate CRT, of whom 101 received additional chemotherapy (5FU or gemcitabine (GEM)). 51/174 (28%) received delayed CRT, and received a median of 4 cycles of GEM prior to CRT. Median follow-up was 33 months (range, 3.6-67). 6/51 (12%) delayed CRT had LR prior to initiation of CRT. 25/51 in the delayed CRT group had a LR (49%) vs. 35/124 patients (28%) in the immediate CRT group. The 1-year LR rates in the immediate and delayed CRT groups were 18% and 40%, respectively (p=0.0093). There was no difference between immediate or delayed CRT, respectively, in mPFS (12.8 mo vs. 12.2 mo, p=0.6544) or mOS (24.8 mo vs. 26.7 mo, p=0.7163). Conclusions: Delayed radiation is associated with an increased risk of LR, though this did not appear to impact PFS or OS.