EORTC trial 22991: Results of a phase III study comparing 6 months of androgen suppression and irradiation versus irradiation alone for localized T1b-cT2aN0M0 prostate cancer.

22 Background: Up to 30% patients irradiated for intermediate- or high-risk localized prostate cancer experience relapse biochemically within 5 years. We assessed if biochemical disease-free survival (BDFS) is improved by adding 6 months of androgen suppression (AS) – twice 3-month depot LHRH-agonist to primary irradiation (RT) for intermediate or high risk localized T1b-cT2a N0M0 prostate cancer. Methods: 819 patients staged cT1b-c with PSA ≥ 10 ng/ml or Gleason ≥ 7 or cT2a (UICC TNM 1997) N0 M0 with PSA ≤ 50 ng/ml were randomized between RT or RT+ADT. Centers elected one dose of prostate irradiation: 70, 74, or 78 Gy. Irradiation of pelvic nodes was left to the discretion of each institution. The trial aimed to show an increase of +7.5% in 5-year BPFS (HR=0.714) with 80% power. This requires 274 events in intent-to-treat analysis. HRQoL was assessed by EORTC QLQ-C30+PR25 (ClinicalTrials.gov NCT00021450). Results: Patients were 70 y old in median, 88% had WHO PS 0, 74.8% were intermediate risk, and 24.8% high risk. In the RT arm, 407/409 received RT, in the RT+ADT, 403/410 received RT+ AS and 3 RT. Six patients refused treatment. After a median follow-up of 7.2 years, 201 and 118 events for BPFS were observed in the RT and RT+ AS arm. RT+ AS improved BPFS compared to RT (HR=0.53, CI: 0.42-0.67, P<0.001) irrespective of the radiation dose (heterogeneity P>0.1). The 5-y BPFS increased from 69.3% to 82.5%. Clinical PFS was also statistically significantly improved (205 events, HR=0.63, CI: 0.48-0.84, P=0.001, +7.9% at 5 years). Late genitourinary toxicity was reported by 5.9% vs. 3.6% of the patients, on RT+ AS and RT, respectively (p=0.14), whereas 27.0% vs 19.4% reported severe impairment of sexual function (p=0.010). Overall HRQoL did not differ between the groups. Hormonal treatment symptoms, sexual activity and functioning scales are clinically significantly impaired by AS at month 6 and year 1; from year 2 no marked difference is seen. Conclusions: The addition of 6 months of medical castration to primary irradiation improves BPFS and PFS in intermediate- and high-risk localized T1b-cT2a N0M0 prostatic carcinoma with no persistent detriment on HRQoL or sexual function. Clinical trial information: NCT00021450.