Background: Investigating oncological outcomes in patients registered in the Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation (J-POPS) in terms of biochemical relapse-free survival (bRFS) by the Phoenix and the newly developed J-POPS definitions, exploration of predictive factors for bRFS, and preliminary verification of pitfalls of prostate-specific antigen (PSA) failure definitions.
Methods: Between July 2005 and June 2007, 2316 clinically localized patients underwent permanent seed implantation. The primary endpoint was bRFS. One of the secondary endpoints was overall survival (OS).
Results: The median age was 69 and performance status was 0 in 99.1% of participants. The median biologically effective dose (BED) was about 180 Gy2. During a median follow-up of 60.0 months, 8.4 and 5.9% had PSA failure by the Phoenix and the J-POPS definitions, respectively. The 5-year bRFSs based on the Phoenix and the J-POPS definitions were 89.1 and 91.6%, respectively. The 5-year OS was 97.3%. According to multivariate analyses, only age affected bRFS based on the Phoenix definition, whereas the risk group and BED independently affected bRFS based on the J-POPS definition. A spontaneous PSA decrease was seen in 91.1% of participants after PSA failure based on the Phoenix definition alone, but in only 22.2% after PSA failure based on the J-POPS definition alone.
Conclusion: The world's largest registration study, J-POPS, consisted of patients with longevity, and a highly quality-controlled BED resulted in excellent bRFS and OS. The high likelihood of PSA bounce by the Phoenix definition should be taken into account, especially in younger patients.
Clinical trial information: NCT00534196.
Keywords: Brachytherapy; External beam radiation therapy; Iodine-125; Prostate cancer.