Significant impact of biochemical recurrence on overall mortality in patients with high-risk prostate cancer after carbon-ion radiotherapy combined with androgen deprivation therapy.

Whether biochemical recurrence (BR) is a significant predictive factor of mortality after definitive radiation therapy for prostate cancer remains unknown. The aim of the current study was to investigate the relation between BR and overall mortality (OAM) in high-risk prostate cancer patients who were treated with carbon-ion radiotherapy (CIRT) and had long-term follow-up in 2 prospective trials.

In the 2 phase 2 clinical trials, which involved 466 prostate cancer patients who received 63.0 to 66.0 Gy of CIRT (relative biological effect) in 20 fractions between 2000 and 2007, 324 patients who were deemed to be at high risk on the basis of the modified D'Amico classification criteria and received CIRT along with androgen-deprivation therapy (ADT) were examined. The OAM rate was adjusted for the ADT duration, and multivariate analyses using a Cox proportional hazards model were performed for OAM with BR as a time-dependent covariate.

The median follow-up period was 107.4 months, and the 5- and 10-year OAM rates after adjustments for the ADT duration were 7.0% (95% confidence interval [CI], 4.0%-9.4%) and 23.9% (95% CI, 16.4%-26.2%), respectively. A multivariate analysis revealed that the presence of BR (hazard ratio, 2.82; 95% Cl, 1.57-5.08; P = .001) was one of the predictive factors for OAM. On the other hand, the duration of ADT had no impact on OAM.

BR after CIRT combined with ADT is an independent predictive factor for OAM in high-risk prostate cancer patients. The results of this study could be applied to other high-dose radiation therapies. Cancer 2016. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.

Cancer. 2016 Jun 28 [Epub ahead of print]

Goro Kasuya, Hitoshi Ishikawa, Hiroshi Tsuji, Takuma Nomiya, Hirokazu Makishima, Tadashi Kamada, Koichiro Akakura, Hiroyoshi Suzuki, Jun Shimazaki, Yasuo Haruyama, Gen Kobashi, Hirohiko Tsujii, Working Group for Genitourinary Tumors

Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan., Department of Radiation Oncology, Graduate School of Medicine, Tsukuba University Faculty of Medicine, Ibaraki, Japan., Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan., Kanagawa Cancer Center, Yokohama, Japan., Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan., Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan., Department of Urology, Japan Community Health Care Organization Tokyo Shinjuku Medical Center, Tokyo, Japan., Department of Urology, Toho University Sakura Medical Center, Chiba, Japan., Department of Urology, Graduate School of Medicine, Chiba University, Chiba, Japan., Department of Public Health, Dokkyo Medical University School of Medicine, Tochigi, Japan., Department of Public Health, Dokkyo Medical University School of Medicine, Tochigi, Japan., Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.

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