Population-based validation of a policy change to use long-term androgen deprivation therapy for cT3-4 prostate cancer: impact of the EORTC22863 and RTOG 85-31 and 92-02 trials.

Purpose: After publication of EORTC-22863 trial, prolonged androgen deprivation therapy (ADT) combined with radiation therapy (RT) became standard policy for high-risk prostate cancer patients in British Columbia (BC) in 1997. We evaluated whether population-based survival improved after this policy change.

Patients And Methods: Two cohorts comprising all patients with T3-T4 prostate cancer treated with curative-intent RT in BC were reviewed. The Early cohort (n=730) was all patients treated between 1993 and 1995, and the Late cohort (n=584) was all patients treated between 1999 and 2001. The BC Cancer Registry, which collects data on survival, was linked to RT and pharmacy databases. Duration of ADT, age, stage, grade, presenting PSA, and Charlson comorbidity index (CCI; none=0, minor=1, major=2+), were abstracted from charts.

Results: Usage of ≥6 months and ≥18 months of neoadjuvant and adjuvant ADT increased from 14% and 1% to 97% and 59% (p<0.0001). Baseline characteristics were similar, except for lower Gleason score (G2-6: 45% vs. 20%, G7: 35% vs. 48%, G8-10: 19% vs. 32%; p<0.0001), higher T-stage (T4: 9% vs. 5%, p=0.004) and higher comorbidity (CCI 0: 62% vs. 71%, CCI 1: 26% vs. 20%, CCI 2+: 11% vs. 9%, p=0.002) in the Early cohort. Disease-specific survival adjusted for competing risks from other causes mortality was improved (90% vs. 86%, p=0.042). On multivariate analysis, the Late cohort was independently associated with improved 8-year overall survival (76% vs. 64%, p=0.0002).

Conclusions: This population-based study demonstrated improved overall survival following a policy change to use of prolonged ADT with curative RT for patients with T3-T4 prostate cancer.