Impact of Long-term Adjuvant Hormonal Therapy in High-dose IMRT for Unfavorable Locally Advanced Prostate Cancer

Abstract

Background/Aim: The aim of this study was to evaluate the benefit of adding long-term adjuvant hormonal therapy to high-dose intensity-modulated radiation therapy for locally advanced prostate cancer patients with multiple unfavorable risks. Patients and Methods: All cT3-4N0M0 prostate cancer patients with Gleason score 8-10 and prostate-specific antigen ≥30 ng/ml who received intensity-modulated radiation therapy to the prostate and seminal vesicle alone (78 Gy in 39 fractions) between September 2000 and June 2017 at our institution were analyzed retrospectively. All patients received short-term neoadjuvant hormonal therapy. Before May 2011, salvage hormonal therapy was initiated when prostate-specific antigen levels exceeded 4.0 ng/ml (early salvage hormonal therapy cohort). In June 2011, 2-year adjuvant hormonal therapy was added (adjuvant hormonal therapy cohort). Clinical outcomes were retrospectively compared using the log-rank test. Results: In total, 88 patients (44 in both cohorts) were analyzed. Median follow-up periods were 10.9 and 6.1 years in early salvage hormonal therapy and adjuvant hormonal therapy cohorts, respectively. No significant difference in overall survival rates was observed (p=0.58). Disease controls were significantly better in the adjuvant hormonal therapy cohort: 95.5 versus 73.6% for castration-resistant prostate cancer-free rate (p=0.04), and 73.6 versus 34.1% for biochemical failure-free rate (p<0.001), both at 8 years, respectively. Conclusion: Among locally advanced prostate cancer patients with multiple unfavorable risks, adding long-term adjuvant hormonal therapy to high-dose intensity-modulated radiation therapy resulted in significantly better disease control than short-term hormonal therapy, even when salvaged early after biochemical failure.