Abstract C057: Pilot study of vaginal microbiome profiles among Black and White endometrial cancer survivors

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Abstract Background: Lower vaginal microbiome diversity, and specifically a Lactobacillus crispatis-dominant vagitype, is associated with more favorable health outcomes. Racial variation in the vaginal microbiome has been reported in some studies, including gynecologic cancers. Racial disparities in endometrial cancer 5-year survival are stark—62% for Black women vs. 83% for White women. Cancer treatments can acutely impact the microbiome of surrounding tissues with potential impacts on quality of life in survivorship, including sexual function. The objectives of this pilot research were to assess the feasibility of self-sampling and variation in vaginal microbiome communities by race, cancer treatment, and sexual function among endometrial cancer survivors. Methods: Endometrial cancer survivors (N=50, mean=11 months from diagnosis) enrolled in the Carolina Endometrial Cancer Study were mailed Genotek vaginal microbiome self-collection kits and the validated Sexual Function-Vaginal Changes Questionnaire (SVQ) before a nurse home visit. Microbiota profiles were characterized by bacteria 16S rRNA amplicon sequencing. Vagitypes were classified as Lactobacillus-dominant and other based on relative abundance (>50% vs. ≤50%) and Ward hierarchical clustering. Results: Overall, 48 vaginal samples were obtained. We excluded samples from women who reported antibiotic use within the last month (N=8) or were missing treatment data (N=6), leaving 34 samples. Of these, 47% were from Black survivors and 53% from White. Cancer treatments were categorized as surgery only (47%) vs. any chemotherapy or radiation (53%); and did not vary by race (p >.9). Black women did not have statistically significant different alpha (Shannon p=0.9) or beta (p=0.4) diversity, or a differential proportion of Lactobacillus dominant vagitype (59% vs. 41%, p=0.3) compared to White women. Alpha (Shannon p=0.04) and beta (p=0.004) diversity varied by cancer treatment with higher microbial diversity after chemotherapy or radiation compared to surgery alone. In the surgery only group, 63% of samples were Lactobacillus dominant, compared to 17% among the chemotherapy or radiation group (p=0.006). We examined cancer treatment associations in analyses restricted to the more favorable endometroid histology (N=25), as surgery alone is associated with endometrioid histology and better prognosis. In this subgroup, 57% (8/14) of women treated with surgery only had Lactobacillus-dominant vagitypes compared to 27% (3/11) in the chemotherapy/ radiation group (p=0.1). Lactobacillus-dominant vagitype was not associated with SVQ scales (global satisfaction; changes in intimacy or interest; dryness; pain). Conclusion: Self-collection of vaginal microbiome samples is feasible in cancer survivors. In our study, Lactobacillus-dominant vagitypes were less abundant among women who were treated with more intensive cancer therapies and did not vary by race or sexual function. Radiation and chemotherapy for endometrial cancer may affect vaginal microbiome composition after treatment ends. Citation Format: Mu Jin, Tope Keku, Nikki McCoy, Jordyn Brown, Jamie Hunter, Victoria Bae-Jump, M. Andrea Azcarate-Peril, Stephanie Engle, Andy Olshan, Hazel B Nichols. Pilot study of vaginal microbiome profiles among Black and White endometrial cancer survivors [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C057.