Seong Il Seo

Introduction This study aimed to analyse the treatment outcomes of moderately hypofractionated radiation therapy (RT) combined with androgen deprivation therapy (ADT) and the prognostic implications of prostate‐specific antigen (PSA) kinetics in high‐risk localized prostate cancer. Methods The medical records of 140 patients who underwent definitive RT (70 Gy in 28 fractions) combined with ADT were retrospectively reviewed. ADT consists of a gonadotropin‐releasing hormone agonist and an anti‐androgen. Clinical outcomes included the biochemical failure rate (BFR), clinical failure rate (CFR), overall survival (OS) and prostate cancer–specific survival (PCSS). The BFR and CFR were stratified by the PSA nadir and the time to the PSA nadir, respectively. Acute and late genitourinary and gastrointestinal adverse events were also recorded. Results The 5‐year BFR, CFR, OS and PCSS rates were 9.8%, 4.5%, 90.2% and 98.7%, respectively. Ninety‐five (67.9%) patients achieved a PSA nadir of 0.01 ng/mL. Patients with a PSA nadir >0.01 ng/mL had a significantly higher BFR and CFR (BFR, P = 0.001; CFR, P = 0.027), even after adjusting for other prognostic factors [per 0.1 ng/mL; BFR, hazard ratio (HR) 4.440, P < 0.001; CFR, HR 4.338, P = 0.001]. However, the time to the PSA nadir and pre‐RT PSA were not significantly associated with the BFR and CFR. Six patients (4.3%) reported grade 3 late adverse events, mostly haematuria and haematochezia. Conclusion Definitive RT with moderate hypofractionation combined with long‐term ADT showed good efficacy for high‐risk localized prostate cancer. The lowest PSA nadir was significantly associated with a low recurrence rate, indicating the importance of PSA follow‐up.