Vaginal Microbiome as a Biomarker of Vaginal Health and Patient-Reported Outcomes in Women Receiving Pelvic Radiation

Abstract

<h3>Purpose/Objective(s)</h3> A potential cause of differences in the extent of vaginal changes after radiation is the vaginal microbiome (VM), which is also highly variable and has been associated with vaginal health. Little is known regarding the impact of an altered VM on vaginal health outcomes. The primary objective of the study is to determine the feasibility of implementing a prospective, comprehensive assessment of women's vaginal health using patient reported outcomes (PROs), physical exam findings, and biological correlatives. Secondary objectives are to determine whether women who experience vaginal toxicity have a distinct VM. We hypothesize that clinician-initiated sample collection for biomarker discovery concurrent with vaginal exams will be feasible and that high pre-treatment <i>Lactobacillus</i> to <i>Prevotella</i> ratio will be associated with post-treatment vaginal symptoms. <h3>Materials/Methods</h3> This is a prospective, observational study of women receiving pelvic radiation for Gyn/GI cancers. Pelvic exam data, vaginal swab, and PROs are collected at baseline and then 1, 3, 6, 12, 18, and 24 months after completion of radiation. Feasibility is defined as clinician-collected biomarker collection concurrent with standard of care exams with >90% accrual and compliance. Preliminary baseline to one-month post-radiation changes in sexual function (FSFI), sexual distress (FSDS), and vaginal length were evaluated by paired t-test, and in vaginal stenosis by Wilcoxon rank-sum test. Vaginal swabs are being prepared for combined transcriptomics and metatranscriptomics with human ribosomal depletion and sequencing (2 × 125bp, sequencing platform). Preliminary analysis from our novel methods to simultaneous evaluate changes in microbe relative abundances, microbe expression, vaginal gene expression, vaginal immune cell abundances, and associations with PROs and objective measures of vaginal changes will be available in the spring 2022. <h3>Results</h3> 39/89 participants have been accrued to the ongoing study – 5 anal SCC, 9 rectal AC, 17 cervical (13 SCC, 4 AC), 7 endometrial (6 endometrioid, 1 carcinosarcoma), 1 vaginal SCC. The mean age is 57.6 years. Most participants are white (87.2%), postmenopausal prior to treatment (62%) and married or partnered (54%). All patients were treated with external beam radiation and 17 also received brachytherapy. Baseline mean FSFI and FSDS scores are 14.2 and 8.8, respectively. No change in FSFI, FSDS, or vaginal length were observed in the initial timepoints (n = 39, p=0.69, p=0.97, and 0.62, respectively). We observed a significant change in vaginal diameter (Wilcoxon rank sum, p = 0.04). Human and microbial RNA has been purified for sequencing. Metatranscriptomic VM data is currently being analyzed to assess for changes. <h3>Conclusion</h3> Our novel comprehensive assessment of women's vaginal health and microbiome collection/analysis has been feasible with early results showing a change in vaginal diameter at one month post radiation. Microbiome analysis is pending.