Abstract 1128: Association between gut microbial change and acute gastrointestinal toxicity in patients with prostate cancer undergoing definitive radiation therapy

Abstract

Abstract Purpose: This prospective cohort study investigated the association between gut microbial changes and acute gastrointestinal toxicities in prostate cancer patients undergoing definitive radiation therapy (RT). Methods: Seventy-nine fecal samples were analyzed. Stool samples were collected at the following timepoints: pre-RT (prRT), 2 weeks after the start of RT (RT-2w), 5 weeks after the start of RT (RT-5w), 1 month after completion of RT (poRT-1m), and 3 months after completion of RT (poRT-3m). We computed the microbial community polarization index (MCPI) as an indicator of RT-induced dysbiosis. Results: Patients experiencing toxicity had lower alpha diversity, especially at RT-2w (P=0.037) and RT-5w (P=0.003). Compared to patients without toxicity, the MCPI in those experiencing toxicities was significantly elevated (P=0.019). In terms of predicted metabolic pathways, we found linearly decreasing pathways including carbon fixation pathways in prokaryotes (P=0.035) and the bacterial secretion system (P=0.005), in patients who experienced toxicities. Conclusions: We showed RT-induced dysbiosis among patients who experienced toxicities. Reduced diversity and elevated RT-related MCPI could be helpfully used for developing individualized RT approaches. Citation Format: Bum-Sup Jang, Dong Soo Lee. Association between gut microbial change and acute gastrointestinal toxicity in patients with prostate cancer undergoing definitive radiation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1128.