Longitudinal vaginal microbiomes and quality-of-life patterns during tamoxifen therapy in breast cancer: a pilot study

초록

Tamoxifen is widely used in breast cancer treatment, but its effects on vaginal microbiome remain poorly understood. This prospective longitudinal pilot study explored vaginal microbiota profiles and quality-of-life parameters in women receiving tamoxifen for breast cancer in Seoul, South Korea (2023-2024). Eleven women initiating tamoxifen therapy were enrolled. Vaginal swabs were collected at baseline (V0) and 6 months (V6). Microbiota was profiled using 16 S rRNA gene sequencing. Quality of life was assessed using the 11-item Menopause Rating Scale. Participants were stratified by baseline colonization patterns. Overall community composition did not show a significant shift between baseline and 6 months. In the full-cohort taxa-level paired analysis, Gardnerella vaginalis (G. vaginalis) showed a nominal, non-FDR-significant increase from baseline to 6 months, and no taxon remained significant after multiple-comparison correction. A negative correlation was observed between G. vaginalis and Lactobacillus iners (L. iners) (rho = -0.6, raw P < 0.01, FDR q < 0.05). Among participants with baseline G. vaginalis detection, 4 of 5 showed increased relative abundance at 6 months, although the confidence interval was wide. G. vaginalis abundance was associated with worse sexual-function-related quality-of-life scores in exploratory analyses, but item-level MRS comparisons did not remain significant after correction for multiple testing. In this small hypothesis-generating pilot cohort, women receiving tamoxifen showed largely stable overall vaginal community composition over 6 months, with an exploratory signal of G. vaginalis expansion among participants colonized at baseline. These findings should be interpreted cautiously given the small sample size, absence of a control group, treatment heterogeneity, and post hoc subgroup analysis, and require validation in larger controlled cohorts.

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