PL04 Presentation Time: 2:45 PM: A Randomized Phase III Trial Comparing Health-Related Quality of Life After Low Dose Rate or High Dose Rate Prostate Brachytherapy Boost Combined with External Beam Pelvic Radiotherapy

Abstract

<h3>Purpose</h3> This randomized phase III trial compared health related quality of life (HRQOL) in urinary, bowel, and sexual domains in men with intermediate (IR) and high-risk (HR) prostate cancer treated with combined external beam radiation therapy (EBRT) and prostate brachytherapy (BT) using either low dose rate (LDR) or high dose rate (HDR). <h3>Materials and Methods</h3> Eligible men receiving pelvic EBRT (46 Gy/23F) combined with prostate BT were randomized to either an LDR (110 Gy) or HDR (15 Gy) boost. HDRBT preceded EBRT by 1 week while LDRBT followed. Time 0 for QOL evaluations was day 1 of any radiotherapy. The Expanded Prostate Cancer Index Composite (EPIC) questionnaire was used to evaluate HRQOL q3 months for the first year, q6 months to 3 years and then annually. The Mann-Whitney U test was used to compare mean EPIC scores for urinary, bowel and sexual summary domains. <h3>Results</h3> From 01/2014 to 01/2020, 191 men were randomized: 42% IR and 58% HR. Median age was 71 years. T stage was T1c/T2a:34%, T2b:28%, T2c:24% and T3:13%. 57% had Gleason 7, 13% Gleason 8 and 30% Gleason 9. 74% received ADT with at least 3 months neoadjuvant and for a median duration of 12 mo. Median follow-up was 48 mo. HDR patients had higher (better) HRQOL urinary domain scores at 3 mo. (79.0 vs. 69.4; p<.001) and 6 mo. (84.0 vs. 76.9; p<.001), and higher bowel domain scores at 3 mo. (87.0 vs. 82.1; p=.005) and 6 mo. (88.7 vs. 82.8; p=.023). Better bowel domain scores were sustained at 24, 36, and 48 mo. In contrast, HDR patients had worse HRQOL urinary domain scores at 1 mo. (73.6 vs. 80.7; p=.003). There was no statistically significant difference in HRQOL sexual domain scores between the two arms. <h3>Conclusions</h3> The effect of HDRBT on urinary and bowel domains was evident 1 mo. post implant but had recovered at 3 and 6 mo., while LDR patients were still experiencing significant QOL impact of their ongoing LDRBT. Although HDR patients sustained an advantage in long term bowel function compared to LDR, there was no difference in long term urinary QOL between the 2 types of BT after the acute phase subsided. The patient treatment experience of combined EBRT/BT is improved with HDR. Efficacy will be reported at 5 year minimum follow up.