Safety and efficacy of intraoperative radiation therapy using a low-energy X-ray source for resectable pancreatic cancer: an interim evaluation of an ongoing prospective phase II study

Objective: The role of intraoperative radiation therapy (IORT) in the management of resectable pancreatic cancer (RPC) remains unclear. To date, the application of IORT using a low-energy X-ray source has not been extensively investigated. Therefore, this study was conducted to evaluate the safety and efficacy of IORT using a 50 kV X-ray source in treating RPC.

Methods: Patients with RPC who underwent radical pancreatectomy and IORT were enrolled. The primary endpoint was time to treatment failure (TTF) survival, whereas the secondary endpoints were safety and overall survival (OS).

Results: By November 2023, 35 patients with RPC were treated according to the study protocol. The median TTF was 11.67 months, whereas the median OS for the cohort was 22.2 months. The local recurrence rate was 20%. The most common postoperative complication was pancreatic fistula. The incidence of delayed gastric emptying was 20%. Within 30 days after surgery, one patient experienced abdominal pain, another experienced vomiting, and one died because of abdominal infection and a grade C pancreatic fistula. Carcinoembryonic antigen (CEA) and D-dimer levels significantly correlated with TTF and OS in multivariate analyses. The carbohydrate antigen 19-9 (CA19-9) level was another prognostic factor significantly associated with OS. Patients with low D-dimer and normal CA19-9 levels showed prolonged OS with an IORT dose ≤ 15 Gy.

Conclusions: This study supports use of IORT with a 50 kV X-ray source in treating RPC. IORT using a low-energy X-ray source was well-tolerated and feasible. Additionally, D-dimer, CEA, and CA19-9 levels may help identify patient profiles potentially benefitting from IORT.