Intraoperative Radiation Therapy (IORT) for Borderline Resectable and Locally Advanced Pancreatic Ductal Adenocarcinoma (BR/LA PDAC) in the Era of Modern Neoadjuvant Treatment: Short-Term and Long-Term Outcomes.

OBJECTIVE: To define short-term and long-term outcomes of IORT for the management of BR/LA PDAC in the era of modern neoadjuvant therapy (NAT). BACKGROUND: In the era of neoadjuvant FOLFIRINOX, many patients with borderline resectable/locally advanced (BR/LA) pancreatic ductal adenocarcinoma (PDAC) become candidates for surgical exploration with curative intent. IORT may be used to consolidate treatment for successfully resected patients with close or positive margins or administered in unresectable patients without distant metastases. METHODS: A retrospective review of 158 patients who received IORT in the setting of biopsy-proven BR/LA PDAC following NAT between 2008 and 2017 was performed. The Kaplan-Meier method was used to analyze progression-free survival (PFS) and overall survival (OS) of FOLFIRINOX treated patients. RESULTS: Most patients (83%) received FOLFIRINOX, and 95% underwent consolidative chemoradiation therapy (50.4-58.8 Gy). Among FOLFIRINOX-treated patients, 86 underwent combined surgical resection with IORT (10 Gy) while 46 received IORT alone (15-20 Gy). The median PFS and OS were 21.5 and 46.7 months for patients who underwent resection with IORT and 14.7 and 23 months in the IORT alone group. Local progression occurred in 12.7% of patients after resection with IORT, and in 15% of patients who received IORT alone. Major complications occurred in 13% of patients following resection, and 5% of patients after IORT alone, including one death. CONCLUSION: IORT combined with surgical resection appears to be associated with improved survival and minimal morbidity in patients with positive or close margins. IORT is also associated with improved survival in patients with unresectable, non-metastatic disease.