Concurrent chemoradiotherapy using proton beams for unresectable locally advanced pancreatic cancer.

•We investigated outcome of chemoradiotherapy using proton beams for pancreatic cancer.•2-year overall survival rate was 50.8% with median 25.6 months.•2-year local control rate 78.9% with median more than 36 months.•Severe gastrointestinal tract adverse events were not observed.•Higher dose delivery to the tumor with proton beams safely lead to longer LC and OS.