Optimal Androgen Deprivation Therapy Combined with Proton Beam Therapy for Prostate Cancer: Results from a Multi-Institutional Study of the Japanese Radiation Oncology Study Group.

Short-term (≤6 months) ADT is beneficial for intermediate-risk PC patients, but likely unnecessary for those with a single risk factor, whereas ADT for >6 months is necessary for high-risk PC patients and ADT for ≥21 months might be optimal for those with multiple risk factors in combination of high-dose PBT.