A retrospective review of the University Health Network (UHN) multimodal treatment experience with extended resection of pancreatic ductal adenocarcinoma (PDAC) in patients with arterial involvement.

447 Background: Involvement of a major artery with PDAC is a criteria of unresectability. Although major vein resection/reconstruction is now accepted in PDAC resection, the feasibility of arterial resection requires investigation. The response to neoadjuvant therapy (NAT) may be a useful tool for identifying appropriate candidates for extended resection. Methods: We retrospectively reviewed the UHN experience of multimodality therapy in patients (pts) with histologically confirmed PDAC and single vessel arterial involvement (superior mesenteric, celiac or hepatic artery) on CT from Jan 2009 to Dec 2013. These pts received NAT prior to being re-assessed for surgery; pts whose disease was either stable or improved were considered for surgery. Baseline imaging was reviewed independently. Postoperative complications were assessed and oncologic outcomes were analysed with Kaplan-Meier method. Results: We identified a cohort of 57 pts of whom 56 received NAT. On reassessment, 26 (46%) had no evidence of disease progression and were considered operable, while 31 had local or distant progression and were deemed inoperable. Of 26 pts proceeding to surgery, 21 (81%) underwent resection and 5 had a palliative procedure. In the resection group, 10 pts required arterial resection/reconstruction to achieve R0. The post-operative mortality at 90-days was 0% and morbidity was 86% with 33% major complications (Clavien-Dindo III-IV). With a median follow-up of 12,1 months, the median survival for the resection group was 18.7 months (95% CI: 11.2-NA) vs. 13.6 months (95% CI: 11.9-18.1) for the non-resection group, P=0.0246. Conclusions: Our results suggest that a multimodal approach including NAT +/- segmental arterial resection/reconstruction, can be considered but with high post-operative morbidity. The encouraging survival rates of pts after extended resection must be balanced with the morbidity of this surgery. Given the poor prognosis of pts with locally advanced PDAC, there is a rationale for prospective evaluation of this approach to identify pts who are most likely to benefit from this aggressive strategy.