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

Abstract

<h3>Purpose/Objective(s)</h3> The aim of this study was to evaluate the survival in oligometastatic prostate cancer patients treated with radiotherapy (RT) for both primary tumor and all metastatic lesions. <h3>Materials/Methods</h3> This was a single-center cohort study. Oligometastatic 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. <h3>Results</h3> This study analyzed 395 patients from 10/2011 to 1/2022 with median follow-up of 42 months. 264 patients (66.8%) were hormone sensitive (HSPC) and 131patients (33.2%) were castrate resistant (CRPC) at the time of RT. 212 patients (53.7%) were synchronous oligometastatic status, 58 patients (14.7%) were metachronous oligometastatic status, and 105 patients (26.6%) were oligoprogressive status. PSMA-PETCT was used for 238 men (60.3%). Before radiotherapy, 12 patients (3.0%) did not receive androgen deprivation therapy (ADT), 252 patients (63.8%) were treated with luteinizing hormone releasing hormone analogue (LHRHa) with or without bikaluamide. 131 patients (33.2%) were treated with LHRHa combined with novel ADT (abiraterone, enzalutamide, apalutamide, etc.), including 3 patients treated with enzalutamide, 2 patients treated with apalutamine, and the rest treated with abiraterone. The most common fractionation scheme of the primary tumor was 2.8Gy for 25 fractions (81.5%). The median BED₃ was 135.3Gy (IQR:128.3-135.3Gy). A total of 247 (62.5%) patients were treated with whole pelvic RT (WPRT). A total of 718 metastatic lesions were treated with RT. The median BED₃ was 121.3Gy (IQR:113.3-131.3Gy). For the whole cohort, the PFS and OS were 62.5% and 92.7% at 3 year, 53.1% and 81.7% at 5 years. Median PFS for men with HSPC was not reached compared with 10 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, ADT type, chemotherapy were associated with improved PFS. <h3>Conclusion</h3> Our study suggests that RT for the primary tumor and all metastatic lesions 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.