Short-term androgen suppression and radiotherapy versus intermediate-term androgen suppression and radiotherapy, with or without zoledronic acid, in men with locally advanced prostate cancer (TROG 03.04 RADAR): an open-label, randomised, phase 3 factorial trial

Summary Background We investigated whether 18 months of androgen suppression plus radiotherapy, with or without 18 months of zoledronic acid, is more effective than 6 months of neoadjuvant androgen suppression plus radiotherapy with or without zoledronic acid. Methods We did an open-label, randomised, 2 × 2 factorial trial in men with locally advanced prostate cancer (either T2a N0 M0 prostatic adenocarcinomas with prostate-specific antigen [PSA] ≥10 μg/L and a Gleason score of ≥7, or T2b–4 N0 M0 tumours regardless of PSA and Gleason score). We randomly allocated patients by computer-generated minimisation—stratified by centre, baseline PSA, tumour stage, Gleason score, and use of a brachytherapy boost—to one of four groups in a 1:1:1:1 ratio. Patients in the control group were treated with neoadjuvant androgen suppression with leuprorelin (22·5 mg every 3 months, intramuscularly) for 6 months (short-term) and radiotherapy alone (designated STAS); this procedure was either followed by another 12 months of androgen suppression with leuprorelin (intermediate-term; ITAS) or accompanied by 18 months of zoledronic acid (4 mg every 3 months for 18 months, intravenously; STAS plus zoledronic acid) or by both (ITAS plus zoledronic acid). The primary endpoint was prostate cancer-specific mortality. This analysis represents the first, preplanned assessment of oncological endpoints, 5 years after treatment. Analysis was by intention-to-treat. This trial is registered with ClinicalTrials.gov , number NCT00193856 . Findings Between Oct 20, 2003, and Aug 15, 2007, 1071 men were randomly assigned to STAS (n=268), STAS plus zoledronic acid (n=268), ITAS (n=268), and ITAS plus zoledronic acid (n=267). Median follow-up was 7·4 years (IQR 6·5–8·4). Cumulative incidences of prostate cancer-specific mortality were 4·1% (95% CI 2·2–7·0) in the STAS group, 7·8% (4·9–11·5) in the STAS plus zoledronic acid group, 7·4% (4·6–11·0) in the ITAS group, and 4·3% (2·3–7·3) in the ITAS plus zoledronic acid group. Cumulative incidence of all-cause mortality was 17·0% (13·0–22·1), 18·9% (14·6–24·2), 19·4% (15·0–24·7), and 13·9% (10·3–18·8), respectively. Neither prostate cancer-specific mortality nor all-cause mortality differed between control and experimental groups. Cumulative incidence of PSA progression was 34·2% (28·6–39·9) in the STAS group, 39·6% (33·6–45·5) in the STAS plus zoledronic acid group, 29·2% (23·8–34·8) in the ITAS group, and 26·0% (20·8–31·4) in the ITAS plus zoledronic acid group. Compared with STAS, no difference was noted in PSA progression with ITAS or STAS plus zoledronic acid; however, ITAS plus zoledronic acid reduced PSA progression (sub-hazard ratio [SHR] 0·71, 95% CI 0·53–0·95; p=0·021). Cumulative incidence of local progression was 4·1% (2·2–7·0) in the STAS group, 6·1% (3·7–9·5) in the STAS plus zoledronic acid group, 1·5% (0·5–3·7) in the ITAS group, and 3·4% (1·7–6·1) in the ITAS plus zoledronic acid group; no differences were noted between groups. Cumulative incidences of bone progression were 7·5% (4·8–11·1), 14·6% (10·6–19·2), 8·4% (5·5–12·2), and 7·6% (4·8–11·2), respectively. Compared with STAS, STAS plus zoledronic acid increased the risk of bone progression (SHR 1·90, 95% CI 1·14–3·17; p=0·012), but no differences were noted with the other two groups. Cumulative incidence of distant progression was 14·7% (10·7–19·2) in the STAS group, 17·3% (13·0&#82 [ABSTRACT FROM AUTHOR]