PARTIQoL is a multi-center phase 3 randomized trial comparing proton and photon for intermediate- or low-risk prostate cancer with a primary endpoint to compare change from baseline in bowel quality of life (QOL) 24 months, and that secondary endpoints include comparison of urinary and sexual functions, toxicity, and efficacy endpoints. A total of 450 patients were recruited, with 13 withdrawals, 437 patients received treatment among whom 59% had intermediate-risk disease, 51% received hypofractionation, 48% used a rectal spacer, and 49% of PBT patients were treated with pencil beam scanning. Patients treated with PBT (N=221) and IMRT (N=216) were followed with a median time of 60.3 months. This study reported no difference between PBT or IMRT in mean change of health care software bowel score at 24 mo (p=0.836), with both arms showing only small, clinically non-meaningful decline from baseline. There was no difference in bowel function at earlier timepoints (3, 6, 9, 12, 18 mo) or later timepoints (36, 48, 60 mo). No differences were observed in other domains (urinary, sexual, hormonal) at any timepoint. There was no difference in progression-free survival (PFS) (93.4% vs 93.7% at 60 mo, p=0.706).