Ten-year survival rates by PSA nadir in patients with metastatic hormone-sensitive prostate cancer: long-term survival analysis from the ECOG-ACRIN 3805 (CHAARTED) trial

BACKGROUND: The CHAARTED trial investigated the long-term survival of patients with metastatic hormone-sensitive prostate cancer (HSPC) treated with androgen deprivation therapy (ADT) with or without docetaxel (Taxotere). This analysis focuses on 10-year overall survival (OS) stratified by disease volume and on-therapy prostate-specific antigen (PSA) levels at 6 months. PATIENTS AND METHODS: OS was calculated using the Kaplan-Meier method from randomization to death or last known alive date. Patients were grouped based on baseline disease characteristics [high-volume (HV) or low-volume (LV)] and PSA levels at 6 months (<0.2 ng/ml versus ≥0.2 ng/ml). Multivariable Cox regression analysis was used to evaluate correlation of PSA nadir with OS adjusted for treatment arm, disease volume, Gleason score, and prior local therapy. RESULTS: Of 790 patients, 225 were without recorded death after a median follow-up of 10 years. The 10-year OS was 25.9% (ADT + docetaxel) versus 22.5% [ADT; hazard ratio (HR) 0.78, P = 0.004]. HV patients treated with docetaxel had significantly higher OS (20.9% versus 11.4%, P < 0.0001). PSA <0.2 ng/ml at 6 months was associated with improved median OS in both ADT + docetaxel (100.3 versus 45.4 months, P < 0.0001) and ADT (116.8 versus 31.8 months, P < 0.0001) arms. PSA nadir <0.2 ng/l at 6 months was an independent predictor of improved OS (HR 0.41, P < 0.0001) adjusting for disease volume, prior local therapy, Gleason score and treatment arm. CONCLUSIONS: Long-term follow-up confirms that ADT + docetaxel significantly improves OS in metastatic HSPC patients with HV disease. PSA nadir <0.2 ng/ml at 6 months is a strong prognostic marker for OS, supporting its use in response-adapted de-escalation strategies.