Progressive Site-Directed Therapy for Castration-Resistant Prostate Cancer: Localization of the Progressive Site as a Prognostic Factor.

Locoregional therapy for oligometastatic prostate cancer has generated great interest. However, its benefit for castration-resistant prostate cancer (CRPC) has not been fully demonstrated. Our objective was to evaluate the treatment outcome of progressive site-directed therapy (PSDT) for oligoprogressive CRPC (OP-CRPC).

This study cohort consisted of 101 patients with CRPC who underwent whole-body diffusion-weighted magnetic resonance imaging between 2014 and 2018, when a new line of anticancer therapy was being considered. For OP-CRPC, PSDT with radiation therapy and unchanged continuation of systemic therapy were recommended.

Thirty-eight patients received a diagnosis of OP-CRPC, and 23 (61%) underwent PSDT at a median prostate-specific antigen (PSA) level of 7.8 ng/mL. The regional radiation therapy targets were the prostate/pelvic lymph nodes (n = 7), bone (n = 15), or both (n = 1). A decrease in PSA levels of at least 50% in response to PSDT (50% PSA decline) was observed in 16 cases (70%); the median time to PSA progression was 8.7 months. Intrapelvic localization of progressive lesions was a significant predictor of time to PSA progression (hazard ratio, 6.6; P = .007) as well as volumes of abnormal signal intensity on whole-body diffusion-weighted magnetic resonance imaging (hazard ratio, 0.5; P = .045). A 50% PSA decline was achieved in 16 of the 18 patients with intrapelvic OP-CRPC (89%) and in none of the 5 patients with non-intrapelvic OP-CRPC (P < .001). Intrapelvic OP-CRPC had a significantly longer time to PSA progression than non-intrapelvic OP-CRPC (10.1 vs 4.8 months, P = .0014).

PSDT can be an effective treatment option for OP-CRPC. Progressive site localization was an important factor in good PSA response.

International journal of radiation oncology, biology, physics. 2019 Jun 12 [Epub ahead of print]

Soichiro Yoshida, Taro Takahara, Yuki Arita, Chikako Ishii, Yusuke Uchida, Keiko Nakagawa, Kazuma Toda, Tsuyoshi Sakamoto, Toshiki Kijima, Minato Yokoyama, Junichiro Ishioka, Yoh Matsuoka, Kazutaka Saito, Ryoichi Yoshimura, Yasuhisa Fujii

Department of Urology, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: ., Department of Biomedical Engineering, Tokai University School of Engineering, Kanagawa, Japan; Advanced Imaging Center, Yaesu Clinic, Department of Radiology, Tokyo, Japan., Advanced Imaging Center, Yaesu Clinic, Department of Radiology, Tokyo, Japan; Department of Diagnostic Radiology, Keio University School of Medicine, Tokyo, Japan., Advanced Imaging Center, Yaesu Clinic, Department of Radiology, Tokyo, Japan., Department of Urology, Tokyo Medical and Dental University, Tokyo, Japan., Department of Radiation Therapeutics and Oncology, Tokyo Medical and Dental University, Tokyo, Japan., PixSpace, Ltd, Fukuoka, Japan.

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