This is a survey study assessing PBT utilization patterns for breast cancer. Of 79 surveys distributed, 28 recipients submitted responses (35 % response rate) representing 15 U.S., 8 European, and 5 Asian centers. Overall, 93 % reported treating breast cancer patients with PBT with 71 % having treated ≥100 breast cancer patients in the US vs. 38 % in Europe and none in Asia. Nearly half (46 %) use moderate hypofractionation (15-20 fractions) for regional nodal irradiation and 42 % conventional fractionation (25-30 fractions). More European centers prefer hypofractionation (88 %) vs. Asian (50 %) and U.S. (21 %) centers (p = 0.003).