Long-term overall survival, progression-free survival, and local control after metastasis-directed external beam radiation therapy plus androgen deprivation therapy in a phase II prospective trial of oligometastatic hormone-sensitive prostate cancer

Abstract

Purpose: Metastasis-directed external beam radiation therapy (EBRT) to all visible oligometastases may improve outcomes for patients with oligometastatic hormone-sensitive prostate cancer (oHSPC). Follow-up for this cohort has been limited to <5 years, and prospective data in de novo oHSPC are lacking. We evaluated long-term outcomes after EBRT and androgen deprivation therapy in patients with oHSPC enrolled on a prospective trial. Methods and materials: From 2006 to 2011, patients with oHSPC and 1 to 5 metastases received 36 weeks of androgen deprivation therapy (luteinizing hormone-releasing hormone agonist plus bicalutamide) and EBRT up to 53 Gy to all visible metastatic lesions. When indicated, the primary prostate tumor or prostate bed received EBRT up to 78 Gy or 66 Gy, respectively. Results: Twenty-nine patients were treated: 15 with de novo metastatic disease and 14 with oligorecurrent disease; 21 patients (72.4%) had bone metastases. The median number of metastases per patient was 1 (range, 1-5). EBRT was delivered to 52 lesions, including 38 bone metastases, 12 pelvic lymph nodes (LNs), and 2 nonpelvic LNs, up to 53 Gy (range, 47-66). Median follow-up was 9.9 years (range, 0.2-14.4). Median overall survival was 9.7 years (95% confidence interval [CI], 5.8-not reached). Median progression-free survival was 1.9 years (95% CI, 1.6-2.2). Patients presenting with prostate cancer-defined de novo metastases had significantly longer median progression-free survival (2.0 years; 95% CI, 1.3-6.0) than patients with oligorecurrent disease (1.8 years; 95% CI, 1.0-2.0; P = .04). Patients with LN-only metastases had numerically longer median progression-free survival (5.8 years; 95% CI, 1.2-not reached) than patients with bone metastases (1.8 years; 95% CI, 1.3-2.0; P = .13). At last follow-up, 17 patients (58.6%) maintained local control of all EBRT-treated metastases. Metastases that locally progressed had previously been controlled for a median of 3.5 years (range, 1.7-10.5). Conclusions: These long-term outcomes after EBRT plus androgen deprivation therapy for oHSPC compare favorably with other reported studies and provide new insight into overall survival, progression-free survival, and local control in this population.