Long-term evaluation of low-dose-rate (LDR) brachytherapy in localized prostate cancer

Abstract

As aresult of technical innovation, i.e., improvement of seed quality, implantation method, and dose calculation, it has been possible to continuously improve oncological results in the treatment of localized prostate cancer with low-dose-rate brachytherapy (LDR-BT). Randomized controlled trials have shown that there is no significant difference in oncological control between the use of radical prostatectomy and LDR-BT in patients with low-risk prostate cancer. The objective of this study was to investigate the oncological efficacy of LDR-BT. A retrospective multicenter analysis was conducted on 618patients treated with LDR-BT as monotherapy, who received adose of 145 Gy. We used iodine125 as the radioactive source. The analysis was conducted with follow-up data from two brachytherapy centers in Germany between 2004 and 2019. The primary endpoint was biochemical relapse-free survival (bRFS), whereby the Phoenix definition (PSA - nadir +2 ng/ml; PSA: prostate-specific antigen) was used to define biochemical relapse, i.e., therapeutic failure. Median follow-up was 52months (range 3-180months). The bRFS across all risk groups was 87.87%. Oncological efficacy was significantly higher in patients with aGleason score of 6 and 7a (p-value < 0.0001); however, there was no significant difference in bRFS between these two groups. Bilateral tumor infiltration or prostate volume had no significant influence on bRFS. Our results show no difference in bRFS between Gleason score6 and7a.