The effects of PSA kinetics on the outcome of hypofractionated salvage radiotherapy for biochemical recurrence of prostate cancer after prostatectomy.

The feasibility and efficacy of hypofractionated salvage radiotherapy (HS-RT) for prostate cancer (PC) with biochemical recurrence (BR) after prostatectomy, and the usefulness of prostate-specific antigen (PSA) kinetics as a predictor of BR, were evaluated in 38 patients who received HS-RT without androgen deprivation therapy between May 2009 and January 2017. Their median age, PSA level and PSA doubling time (PSA-DT) at the start of HS-RT were 68 (53-74) years, 0.28 (0.20-0.79) ng/ml and 7.7 (2.3-38.5) months, respectively. A total dose of 60 Gy in 20 fractions (three times a week) was three-dimensionally delivered to the prostate bed. After a median follow-up of 62 (30-100) months, 19 (50%) patients developed a second BR after HS-RT, but only 1 patient died before the last follow-up. The 5-year overall survival and BR-free survival rates were 97.1 and 47.4%, respectively. Late grade 2 gastrointestinal and genitourinary morbidities were observed in 0 and 5 (13%) patients, respectively. The PSA level as well as pathological T-stage and surgical margin status were regarded as significant predictive factors for a second BR by multivariate analysis. BR developed within 6 months after HS-RT in 11 (85%) of 13 patients with a PSA-DT < 10 months compared with 1 (17%) of 6 with a PSA-DT ≥ 10 months (median time to BR: 3 vs 14 months, P < 0.05). Despite the small number of patients, our HS-RT protocol seems feasible, and PSA kinetics may be useful for predicting the risk of BR and determining the appropriate follow-up schedule.

Journal of radiation research. 2020 Sep 05 [Epub ahead of print]

Hitoshi Ishikawa, Keiko Higuchi, Takuya Kaminuma, Yutaka Takezawa, Yoshitaka Saito, Toru Etsunaga, Kazushi Maruo, Hidemasa Kawamura, Nobuteru Kubo, Takashi Nakano, Mikio Kobayashi

Department of Radiation Oncology, Isesaki Municipal Hospital, Tsunatorimoto 12-1, Isesaki, 372-0802 Gunma, Japan., Department of Radiation Oncology, Gunma University Graduate School of Medicine, Showa 3-39-22, Maebashi, 371-8511 Gunma, Japan., Department of Urology, Isesaki Municipal Hospital, Tsunatorimoto 12-1, Isesaki, 372-0802 Gunma, Japan., Department of Biostatistics, Faculty of Medicine, University of Tsukuba, Tennodai 1-1-1, Tsukuba, 305-8575 Ibaraki, Japan., Hospital of the National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Sciences and Technology, Anagawa 4-9-7, Inage, 263-8555 Chiba, Japan.