204P - The effect of radium-223 therapy in agent orange related veterans with metastatic castrate resistance prostate carcinoma (CRPC)

Abstract

BackgroundRa-223 radioisotope has been reported to increase median survival in bone metastatic prostate carcinoma. The addition of Ra-223 to abiraterone was associated with an increased risk of bone fractures. There is no comprehensive data for using Ra-223 in veteran population. MethodsWe present a retrospective study of patients (pts) with bone metastatic CRPC who received standard doses of Ra-223 and other sequential therapies at VAPHS from 2014 to 2018. Pts were divided into agent orange exposure (AO) and no exposure (Non-AO). Time to study was calculated from the initiation of Ra-223. Time to skeletal related events (SRE), progression of PSA, bone metastasis and alkaline phosphatase (ALP) were calculated in months (mos) using unpaired T-test with two-tailed p value. Median survival was calculated by Kaplan Meier R log rank test. ResultsThere were 34 pts with bone metastatic CRPC. 17 pts (50%) were AO, 17 pts (50%) Non-AO. The mean age of diagnosis of AO was 62 y/o and Non-AO was 69 y/o (p 0.005). The mean Gleason score for AO was 8.12 and Non-AO was 8.00 (p 0.7048). The median number of Ra-223 cycles was 6 (60%). 10 pts received Ra-223 as first line (29%) and 24 pts received Ra-223 later (71%). There were 12 SRE with median survival of 15 mos. There was no difference in mean time to SRE between AO (8 pts, 10.63 mos) and Non-AO (4 pts, 10.25 mos) with p 0.9306. The mean time to PSA progression for AO was 5.40 mos and Non-AO was 6.79 mos (p 0.2808). Mean time to bone progression for AO was 7.56 mos and Non-AO was 10.14 mos (p 0.1574). Mean time to ALP progression for AO and Non-AO was 6.25 mos and 8.71 mos respectively (p 0.0512). 20 patients (58%) had died. Median survival for Ra-223 first was 32 mos and for Ra-223 later was 15 mos with p 0.14 and HR 0.48 (95% CI, 0.17 to 1.3). Median survival between AO and Non-AO was 12 mos and 18 mos respectively with p 0.15 and HR 2.0 (95% CI, 0.77 to 5). ConclusionsThere is no statistical difference between AO and Non-AO in terms of time to SRE, PSA, bone and ALP progression even though there is a trend of shorter duration in AO veterans. There is no median survival difference between Ra-223 first versus Ra-223 later as well as between AO and Non-AO but there is a trend of worse survival in AO veterans. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.