Proton Radiotherapy for Isolated Local Recurrence of Primary Resected Pancreatic Ductal Adenocarcinoma

BackgroundThe optimal treatment for isolated local recurrence (ILR) of pancreatic adenocarcinoma (PDAC) after surgical resection remains unclear. This study aimed to evaluate the safety and efficacy of proton radiotherapy (PRT) for ILR of PDAC after surgery.MethodsThe medical records of patients with ILR of PDAC after surgery who underwent proton beam therapy between 2011 and 2015 at Hyogo Ion Beam Medical Center were retrospectively studied.ResultsThe study analyzed 30 patients (14 women and 16 men) with a median age of 65years (range 38-81years) who had initially undergone pancreatoduodenectomy (n=23) or distal pancreatectomy (n=7) for their primary tumors. Upon ILR, PRT was administered with a median total cumulative dose of 67.5gray equivalent (GyE) (range 50-67.5GyE) using 19 to 25 fractions. For 25 patients, concurrent chemotherapy was administered using gemcitabine (n=18) or S-1 (n=7). Four patients (13.3%) experienced acute grade >= 3 gastrointestinal toxicities. After a median follow-up period of 17.6months (range 2.1-50.4months), 23 patients had experienced tumor progression and 10 had died. Nine patients (30%) experienced local tumor progression. The median overall, progression-free, and local progression-free survival rates were 26.1, 12.3, and 41.2months, respectively. Pre-PRT serum levels of cancer antigen 19-9 higher than 100U/mL and duke pancreatic monoclonal antigen type 2 higher than 150U/mL were significantly associated with shorter progression-free survival rates.ConclusionsProton radiotherapy for ILR of PDAC after surgery is well tolerated and produces good locoregional control and should be considered for eligible patients.