High-dose-rate brachytherapy with external beam radiotherapy versus low-dose-rate brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer

Abstract

To compare the outcomes of localized prostate cancer treatment with high-dose-rate brachytherapy (HDR-BT) and low-dose-rate brachytherapy (LDR-BT), we examined 924 patients treated with HDR-BT\u2009+\u2009external beam radiotherapy (EBRT) and 500 patients treated with LDR-BT\u2009±\u2009EBRT using multi-institutional retrospective data. The HDR-BT treated advanced disease with more hormonal therapy than LDR-BT. To reduce background selection bias, we performed inverse probability of treatment weighting (IPTW) analysis using propensity scores and excluded patients with T3b-4 disease/ initial prostate-specific antigen (PSA) levels\u2009>\u200950 ng/ml. The actuarial 5-year biochemical control rates (5y-bNED) were 96.3% and 95.7% in the HDR-BT and LDR-BT groups, respectively. The corresponding values were 100% and 96.5% in the low-risk group; 97.4% and 97.1% in the intermediate-risk group (97.2% and 97% in the higher titer group and 97.5% and 94.6% in the lower titer group, respectively); and 95.7% and 94.9% in the selected high-risk group, respectively. IPTW correction indicated no significant difference among the groups. The 5y-bNED in the HDR-BT\u2009+\u2009EBRT, LDR-BT\u2009+\u2009EBRT, and LDR-BT alone groups were 96.3%, 95.5%, and 97%, respectively (P\u2009=\u20090.3011). The corresponding values were 97.4%, 94.7%, and 96.6% (P\u2009=\u20090.1004) in the intermediate-risk group (97.5%, 100%, and 94.5% in the lower titer group [P\u2009=\u20090.122] and 97.2%, 96.2%, and 100% [P\u2009=\u20090.664] in the higher titer group, respectively) and 95.7%, 95.5%, and 100% (P\u2009=\u20090.859) in the high-risk group, respectively. The HDR-BT group showed a lower incidence of acute grade\u2009≥\u20092 genitourinary toxicities; the incidence of other early and late grade\u2009≥\u20092 toxicities were similar between the HDR-BT and LDR-BT groups. Acute genitourinary toxicity predicted the occurrence of late genitourinary toxicity. EBRT increased the risk of grade\u2009≥\u20092 gastrointestinal toxicity. HDR-BT\u2009+\u2009EBRT is a good alternative to LDR-BT\u2009±\u2009EBRT for low-, intermediate-, and selected high-risk patients.