Intraoperative radiation therapy (IORT) for borderline resectable and locally advance pancreatic cancer (BR/LA PDAC) in the era of modern neoadjuvant treatment: short- and long-term outcomes

Abstract

Background: In the era of neoadjuvant FOLFIRINOX, many patients with borderline resectable/locally advanced pancreatic ductal adenocarcinoma (BR/LA PDAC) are candidates for surgical exploration with curative intent. For successfully resected patients with close or positive margins, IORT may be used to consolidate treatment. Furthermore, it may be administered in patients who are deemed unresectable without distant metastases. Herein, we describe our contemporary experience with 158 patients who received IORT after neoadjuvant therapy for BR/LAPDAC. Methods: A retrospective chart review of all patients at Massachusetts General Hospital who received IORT in the setting of biopsy-proven BR/LA PDAC following NT between 2008 and 2017 was performed. The Kaplan-Meier method was used to summarize and plot the distribution of progression-free survival (PFS) and overall survival (OS). Results: Most patients (83%) received FOLFIRINOX, and 95% underwent consolidative chemoradiation therapy (50.4 – 58.8 Gy). Ninety-four patients underwent combined surgical resection with IORT (10Gy) while 63 patients received IORT alone (15–20 Gy). Clavien-Dindo grade III/IV complications occurred in 13% following resection and 5% after IORT alone. There was one postoperative death (0.6%). Among patients treated with FOLFIRINOX, median PFS and OS were 21.2 and 46.6 months in patients who were resected and received IORT, and 10.5 and 23 months in the IORT alone group. Overall 1, 2, and 4-year survival rates were 98.8%, 79.2%, and 47.3% after resection with IORT, and 97.8%, 49.1%, and 13.1% after IORT alone (Figure 1). Notably, 2 patients who did not undergo resection and were treated with IORT have had PFS of 6.0 and 6.8 years post-treatment. Conclusion: IORT is a useful adjunct in the management of BR/LA PDAC either in conjunction with resection or as sole therapy. It does not appear to increase adverse short-term outcomes and may confer a survival benefit in patients who undergo resection and have positive or close margins, but also as sole therapy in patients with unresectable pancreatic cancer without metastases.