Abstract 204P
Background
Ra-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.
Methods
We 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.
Results
There 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).
Conclusions
There 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.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
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