Adjuvant androgen deprivation (ADT) versus mitoxantrone plus prednisone (MP) plus ADT in high-risk prostate cancer (PCa) patients following radical prostatectomy: A phase III intergroup trial (SWOG S9921) NCT00004124.
2 Background: High risk localized Pca patients are more likely to relapse and suffer morbidity/mortality from metastatic disease after prostatectomy. Adjuvant ADT can reduce this risk. We hypothesized that MP in addition to two years of ADT could further reduce mortality from PCa. Methods: Participants with clinically localized (T1-T3, N0, M0) PCa received radical prostatectomy. Eligibility required ≥ 1 high risk criteria defined as Gleason sum ≥8; pT3b or pT4 or N1; Gleason 7 with positive margin; any one of these preoperative findings: PSA>15ng/ml, biopsy Gleason >7, biopsy Gleason >6 with PSA>10. ADT arm consisted of bicalutamide and goserelin for 2 years. ADT+MP arm received ADT plus 6 cycles of M 12mg/m2+ P 5mg BID. Primary endpoint was survival (OS). Median OS was anticipated to be 10 years in ADT arm requiring 680 patients/arm to detect a hazard ratio of 1.30 with 92% power and one-sided α=0.05. Results: S9921 enrolled patients from 10/99 to 1/07 when the DSMC recommended stopping due to increased incidence of leukemia in the ADT+MP arm. Of 983 patients randomized, 22 ineligible. 481 eligible on ADT and 480 on ADT+MP. Patients were stratified by stage (≤pT2, ≥pT3, N0 or N+), Gleason score, and intent to receive adjuvant radiation (RT) (Y/N). Median age was 60 years, 84% were white, presurgical PSA was 7.6 ng/ml, 16% had positive nodes, 26% intended to receive RT, 63% had positive margins. 11 ADT and 20 ADT+ MP received no protocol treatment. Median follow-up is 11.2 years. Conclusions: Survival was greater than anticipated in both arms. MP increases the risk of leukemia. There is no evidence that MP improves PCa specific survival when added to 2 years of adjuvant ADT. Clinical trial information: NCT00004124. [Table: see text]