Long-Term Outcomes of Adjuvant Treatment in High-Risk Prostate Cancer
As reported by Hussain et al in the Journal of Clinical Oncology, long-term follow-up of the phase III SWOG S9921 trial showed that the addition of adjuvant mitoxantrone and prednisone (MP) to androgen-deprivation therapy (ADT) did not improve survival and increased death from other malignancies in high-risk prostate cancer. Outcomes with 2 years of ADT were encouraging. Study accrual was halted in 2007 as a result of a higher leukemia incidence in the group receiving MP.
Study Details
In the trial, 961 patients were randomized between October 1999 and January 2007 to receive 6 cycles of MP plus ADT (bicalutamide and goserelin [Zoladex]) for 2 years (n = 480) or ADT alone (n = 481) after radical prostatectomy. Patients had to have cT1–3N0 disease with ≥ 1 high-risk factor after prostatectomy, consisting of Gleason score ≥ 8; pT3b, pT4, or pN+ disease; Gleason score = 7 and positive margins; or preoperative prostate-specific antigen (PSA) > 15 ng/mL, biopsy Gleason score > 7, or PSA > 10 ng/mL plus biopsy Gleason score > 6.
The primary endpoint was overall survival.
Overall and Disease-Free Survival
Median follow-up was 11.2 years. Estimated 10-year overall survival was 87% in the ADT group vs 86% in the ADT-plus-MP group (hazard ratio = 1.06, 95% confidence interval = 0.79–1.43). Estimated 10-year disease-free survival was 72% in both groups. Among all deaths, 18% in the ADT group vs 22% in the ADT-plus-MP group were due to prostate cancer and 18% in the ADT group vs 36% in the ADT-plus-MP group were due to other cancers.
The investigators concluded, “MP did not improve [overall survival] and increased deaths from other malignancies. The [disease-free survival] and 10-year [overall survival] in these patients treated with 2 years of ADT were encouraging compared with historical estimates, although a definitive conclusion regarding value of ADT may not be made without a nontreatment control arm.”
The study was supported by the National Cancer Institute, AstraZeneca Pharmaceuticals, and Immunex Corporation (Amgen).
Maha Hussain, MD, of the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, is the corresponding author for the Journal of Clinical Oncology article.
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