Long-term outcome by risk factors using conformal high-dose-rate brachytherapy (HDR-BT) boost with or without neoadjuvant androgen suppression for localized prostate cancer.

PURPOSE: The aim of this study is to analyze, during the prostate-specific antigen (PSA) era, the long-term outcome of patients treated with conformal high-dose-rate (HDR) brachytherapy boost to the prostate with or without androgen deprivation therapy (ADT) when patients are stratified by risk factors for failure. METHODS AND MATERIALS: Between 1986 and 2000, 611 patients were treated for clinically localized prostate cancer in three prospective trials of external beam radiation therapy (EBRT) and dose-escalating HDR brachytherapy (BT) boost. There were 104 patients treated at Seattle, 198 at Kiel University, and 309 at William Beaumont Hospital. Of the 611 patients, 177 received a short course of neoadjuvant/concurrent ADT. The patients were divided into three risk groups. Group I, comprised of 46 patients, had stage < or =T2a, Gleason score (GS) < or = 6, and initial PSA (iPSA) < or = 10 ng/mL. Group II comprised 188 patients with stage > or =T2b, GS > or = 7, and iPSA > or = 10, with any one factor higher. Group III included 359 patients with any two risk factors higher. The American Society for Therapeutic Radiology and Oncology definition for biochemical failure was used. RESULTS: The mean follow-up was 5 years (range, 0.2-15.3). For the 611 patients, the 5-year and 10-year biochemical control (BC) rates were 77% and 73%, disease-free survival (DFS) was 67% and 49%, and cause-specific survival (CSS) was 96% and 92%, respectively. BC at 5 years for Group I patients was 96%, for Group II 88%, and for Group III patients 69%. CSS at 5 years was 100% in Group I, 99% in Group II, and 95% in Group III patients. In univariate and multiple regression analyses for BC, risk group, stage, iPSA, and GS were significant in predicting failure. However, age, follow-up interval, and ADT did not. CONCLUSIONS: EBRT with HDR-BT produced excellent long-term outcomes in terms of BC, DFS, and CSS in patients with prostate cancer even for those at highest risk. Conformal HDR-BT is both a precise dose delivery system and an effective treatment for both favorable and unfavorable prostate cancer. The addition of a short course of neoadjuvant/concurrent ADT failed to improve outcome. The results were similar at all three institutions, giving credence to the reproducibility of the brachytherapy treatment.

Hypofractionated conformal HDR brachytherapy in hormone naïve men with localized prostate cancer. Is escalation to very high biologically equivalent dose beneficial in all prognostic risk groups?

PURPOSE: To analyze the long-term effect of local dose escalation using conformal hypofractionated high-dose-rate brachytherapy (HDR-BT) boost and pelvic external-beam radiation therapy (EBRT) in hormone-naïve men with localized prostate cancer. PATIENTS AND METHODS: A total of 579 men were consecutively treated with pelvic EBRT and dose escalating HDR-BT since 1986 in two prospective trials: 378 patients at William Beaumont Hospital (1991-2002), and 201 patients at Kiel University (1986-1999). BT optimization was done modulating both, the dwell times and spatial source positions. A short course of neoadjuvant/concurrent androgen deprivation therapy was given to 222 patients. Hormone-naïve patients only (n = 324) with a follow-up > or = 18 months were analyzed. All patients had at least one poor prognostic factor (stage > or = T2b, Gleason Score > or = 7, pretreatment prostate-specific antigen [PSA] > or = 10 ng/ml): any one factor 122 patients, any two factors 122 patients, and three factors 80 patients. This cohort was stratified by equivalent dose (ED): dose level 1, < or = 94 Gy, n = 58, and dose level 2, > 94 Gy, n = 266, assuming an alpha/beta ratio of 1.2. The ASTRO definition for biochemical failure was used. RESULTS: Mean follow-up was 5.3 years (1.5-13.9 years). For all 324 patients, the 5-year biochemical control (BC) rate was 79%. Cancer-specific survival was 98%, and overall survival 90%. Similar analysis by institution demonstrated no difference in outcomes. For the entire cohort of hormone-naïve men, dose escalation to > 94 Gy resulted in a better 5-year BC of 59% versus 85% (p < 0.001). Discriminating by risk group a striking dose escalation effect was seen in the groups with two or three poor prognostic factors (p = 0.022 and < 0.001, respectively). In the group with only one poor prognostic factor, no statistical difference could be detected questioning the need for ED > 94 Gy. CONCLUSION: The results demonstrate that conformal HDR-BT is a successful method for delivering very high radiation dose to the prostate. The ability to escalate dose to ED > 94 Gy was reflected in improved long-term outcomes in terms of BC, significantly for those patients with two or three poor prognostic factors reaching BC rates of 85%.