Androgen Deprivation and Radiation with Helical Tomotherapy to Metastases in Patients with Oligometastatic Hormone - Sensitive Prostate Cancer

ABSTRACT Background Metastatic prostate cancer (PC) is treated with androgen deprivation therapy (ADT) and subsequent treatments are employed only after the development of castration resistance. We hypothesized that treatment of oligometastases with external beam radiation therapy (EBRT) concurrent with ADT will be feasible and safe and may provide therapeutic benefit by more effective reduction in the tumor burden. Methods Patients (pts) with hormone sensitive PC (HSPC) and 1-5 metastases (mts) detected by bone scan and CT scan were treated with 36 weeks of LHRH agonist combined with bicalutamide and EBRT up to 45 Gy to all visible metastatic sites. Seventeen pts (59%) who had no prior therapy of the primary tumor, also received up to 78 Gy to the prostate. Primary objectives were time to treatment failure (TTF) and toxicity. TTF was calculated from the end of therapy until PSA reached pre-treatment level or 10 (whichever was lower) or radiographic progression or until ADT was restarted. Results Twenty nine pts were treated. Median number of mts was 1. Median Gleason score was 8 (range 5-10). Median baseline PSA was 11.4 (range 1-74.5). Twenty one pts (72%) had bone mts, 13 pts (45%) had lymph node (LN) mts and 8 pts (28%) had mts limited to pelvic LNs. Median follow up was 25.7 months (range 13.4-61.4). Grade 3 toxicities included diarrhea (7%), urinary frequency (3%), renal insufficiency (3%). Twenty five pts (86%) reached PSA nadir of Conclusions EBRT to multiple oligometastatic sites of HSPC is feasible. Majority of pts achieved PSA nadir associated with favorable prognosis. Pts with mts limited to pelvic LNs maintain prolonged disease control off ADT. Pts with oligometastases represent a distinct subset of HSPC that may serve as a focus for clinical trials evaluating novel local and systemic therapies in combination with ADT. Disclosure All authors have declared no conflicts of interest.