Phase 2 Randomized Study of Radiation Therapy and 3-Year Androgen Deprivation With or Without Concurrent Weekly Docetaxel in High-Risk Localized Prostate Cancer Patients

Purpose: Docetaxel improves survival in patients with metastatic prostate cancer. This randomized phase 2 trial aimed to assess the activity of weekly docetaxel with radiation therapy (RT) plus androgen deprivation in patients with high-risk localized prostate cancer. The study examined the benefit of 9 weekly docetaxel administrations to RT plus 3 years of luteinizing hormone-releasing hormone analogues.

Methods and materials: A total of 132 patients were recruited for the study. Patients' characteristics included T3-T4 stage (81.1%), Gleason score ≥8 (77.3%), prostate-specific antigen level >20 ng/mL (28.9%), and pN+ (18.2%). All patients included in the trial received either the standard-of-care control arm with luteinizing hormone-releasing hormone analogues plus RT (arm A) or the experimental arm (RT + 9 weekly cycles of docetaxel + 3 years of androgen deprivation therapy, arm B). The primary objective was to achieve a high percentage of patients who were free of biochemical recurrence within 5 years of randomization. Secondary endpoints included biochemical recurrence-free survival (BRFS), progression-free survival (PFS), overall survival (OS), clinical response rate, biochemical response rate, and toxicity.

Results: No difference between the arms of the study was found in biochemical recurrence (93.4% at 60 months for arm A vs 85.3% for arm B; P = .3297). PFS at 60 months was 93.4% and 83.7% in arms A and B, respectively (P = .2532). Five-year survival was 93.3% (95% confidence interval, 83.1-97.45) in arm A versus 93.6% (83.8-97.55) in arm B; median PFS and OS have not been reached. Prostate-specific antigen level ≤0.2 ng/mL at 3 months after the end of treatment was seen in 81.25% of patients in arm A compared with 90.48% of patients in arm B (P = .2028). BRFS was not significantly different between treatment arms. Diarrhea was the main nonhematologic toxicity. Long-term follow-up has not yet been enough to meet median PFS and OS.

Conclusions: Concurrent weekly docetaxel can be administered safely with standard doses of RT without a significant increase in the toxicity profile. No statistically significant differences for 5-year BRFS, PFS, and OS have been observed when docetaxel was added to conventional treatment.