A phase II trial of neoadjuvant chemoradiotherapy with intensity-modulated radiotherapy combined with gemcitabine and S-1 for borderline-resectable pancreatic cancer with arterial involvement

Purpose Chemoradiotherapy using intensity-modulated radiotherapy (IMRT) is expected to provide a powerful alternative to conventional chemotherapy with a low incidence of adverse events. This study evaluated the efficacy of intensity modulated radiotherapy in combination with gemcitabine and S-1 as neoadjuvant chemoradiotherapy (NACRT) for borderline-resectable pancreatic cancer with arterial involvement (BR-A). Methods A total of 27 patients with BR-A were enrolled in this study between February 2012 and September 2015. IMRT was administered at 50.4 Gy in 28 fractions with concurrent gemcitabine at a dose of 600 mg/m 2 and S-1 at a dose of 60 mg. Results Only one patient (3.5%) experienced gastrointestinal adverse events at grade 3 or higher. Nineteen patients (70.3%) underwent resection, and R0 resection was achieved in 18 patients (94.7%). Thirteen patients (68.4%) developed distant metastasis at the initial site of recurrence after resection. Local recurrence developed in only one of these patients (7.7%). The median overall survival and 1-year survival rates were 22.4 months and 81.3%, respectively. Conclusions Concurrent IMRT with gemcitabine and S-1 for patients is feasible as NACRT for BR-A with low gastrointestinal toxicity. IMRT can be employed as a standard radiotherapy to provide more effective NACRT with powerful chemotherapy drugs.