Radiotherapy of the Primary Tumor and All Metastatic Lesions in Synchronous Oligometastatic Prostate Cancer

Abstract

The aim of this study was to evaluate the survival in synchronous oligometastatic prostate cancer patients treated with radiotherapy (RT) for both primary tumor and all metastatic lesions.This was a single-center cohort study. Synchronous oligometastatic (≤5) prostate cancer patients with RT for both primary tumor and all metastatic lesions were included. Kaplan-Meier method, log rank test and cox regression were used to calculate OS and PFS. PFS included PSA failure, local or distant failure assessed by imaging.This study analyzed 60 patients from 10/2011 to 12/2017 with median follow-up of 48 months. All patients had metastatic disease at the time of initial diagnosis and all patients received androgen deprivation therapy (ADT). Forty-four (73%) patients were hormone sensitive (HSPC) and 16 (27%) patients were castrate resistant (CRPC) at the time of RT. PSMA PET/CT was used for 7 (12%) men. The most common fractionation schemes of the primary tumor were 2 Gy for 35-38 fractions (67%) and 2.7-2.8 Gy for 13 fractions (22%). The median BED3 was 126 Gy (range, 100-128 Gy). A total of 37 (62%) patients were treated with whole pelvic RT (WPRT). A total of 87 metastatic lesions were treated with RT. The median BED3 was 120 Gy for metastatic lesions (range, 63-139 Gy). For the whole cohort, the PFS and OS were 51.4% and 47.4% at 4 years. Median PFS for men with HSPC was 78 months compared with 11 months in men with CRPC. Median OS for men was 45 months in men with CRPC. On univariable analysis, HSPC, shorter interval between diagnosis and RT, lower pre-RT PSA, lower Gleason score, lower metastatic burden/volume, use of WPRT were associated with improved PFS.Our study suggests that RT for the primary tumor and all metastatic lesions plus systemic therapy has better survival than clinical studies of prostate radiotherapy alone, especially for patients with HSPC, shorter interval between diagnosis and RT and lower metastatic burden/volume.