Potential Role of Proton Beam Therapy for Locally Advanced Pancreatic Cancer

Background/Aim: Proton beam therapy (PBT) has emerged as an alternative to conventional photon therapy for locally advanced pancreatic cancer (LAPC). This study evaluated the outcomes and adverse events of PBT combined with chemotherapy in LAPC, with outcomes of chemotherapy alone presented for reference. Patients and Methods: This study included 58 patients diagnosed with LAPC between January 2016 and December 2022. We analyzed data from 14 patients receiving chemoradiotherapy with PBT of 67.5 Gy relative biological effectiveness in 25 fractions (PBT group). As a reference, data from 32 patients receiving chemotherapy alone were analyzed (chemotherapy group). PBT with concurrent chemotherapy was initiated in patients without distant metastasis after upfront chemotherapy, and all patients subsequently underwent maintenance chemotherapy. Overall survival (OS), progression-free survival (PFS), local control (LC), and distant metastasis-free survival (DMFS) were evaluated using the Kaplan–Meier method. Results: In the PBT group, the median interval from chemotherapy initiation to PBT was 180 days. The 1-year/2-year OS and PFS rates were 92.9%/57.1% and 78.6%/42.9%, respectively. The corresponding LC and DMFS rates were 85.7%/77.1% and 85.7%/60.6%. Gastrointestinal adverse events in the PBT group included gastric perforation, gastric antral vascular ectasia, and bile duct stenosis in one patient each (7.1%). In the chemotherapy group, the 1-year/2-year OS and PFS rates were 74.4%/32.0% and 36.8%/13.4%, respectively, while LC and DMFS rates were 44.4%/18.4% and 44.0%/27.0%. Conclusion: Chemoradiotherapy with PBT yielded favorable outcomes in patients with LAPC, suggesting that PBT is a promising treatment option.