This study included 93 patients with mCRPC that were examined retrospectively. Patients were divided into two groups between patients with radiation therapy after CRPC (n=32) diagnosis and without radiation therapy (n=61). The authors compared oncological outcomes, including cancer-specific survival (CSS) and OS between the two groups. Multivariate Cox regression analyses using the inverse probability of treatment weighting (IPTW) method were used to evaluate the impact of radiation therapy on CSS and OS.
The median age at CRPC diagnosis was 74 years, and median follow-up periods after CRPC diagnosis were 24 months. The median time from CRPC diagnosis to radiation therapy initiation was 11 months and the rate of adverse events related to radiation therapy in any grade was 60% and >=grade 3 was 20%. The median PSA decline rate for RT was 41% and 13 patients experienced a >=30% PSA decline after radiation therapy. Although CSS tended to be higher in the radiation therapy group, it was not significant (p = 0.106); OS was significantly higher in the radiation therapy group (p = 0.02).
In multivariate Cox regression analyses with IPTW model, RT was not significantly associated with CSS (HR 0.36, 95%CI 0.12-1.08), but was for OS (HR 0.28, 95%CI 0.09-0.80).
Despite the clear limitations associated with this study with respect to selection bias, these results are hypothesis generating. The authors concluded that radiation therapy might improve oncological outcomes even in patients with mCRPC. They aim in future work to identify the adequate candidates of radiation therapy in patients with mCRPC.
Presented by: Naoki Fujita, Department of Urology, Hirosaki University Graduate School of Medicine, Aomori, Japan
Written by: Zachary Klaassen, MD, MSc, Assistant Professor of Urology, Georgia Cancer Center, Augusta University, Medical College of Georgia, Twitter: @zklaassen_md at the American Urological Association's 2019 Annual Meeting (AUA 2019), May 3 – 6, 2019 in Chicago, Illinois
Co-authored by: Masaki Momota, Yuki Tobisawa, Tohru Yoneyama, Hayato Yamamoto, Atsushi Imai, Shingo Hatakeyama, Hirosaki, Japan, Hiroyuki Ito, Hachinohe, Japan, Takahiro Yoneyama, Yasuhiro Hashimoto, Hirosaki, Japan, Kazuaki Yoshikawa, Mutsu, Japan, Chikara Ohyama, Hirosaki, Japan
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