Endometrial microbiota from endometrial cancer and paired pericancer tissues in postmenopausal women: differences and clinical relevance

Objective: The incidence of postmenopausal endometrial cancer (EC) is rising, and the uterine microbiota has recently been suggested to be an etiology of EC. However, the differences in microbiota profiles in paired EC and the adjacent non-EC endometrium, and the functional microbiota of clinical relevance remain largely unknown. Therefore, we examined the differences in microbiota profiles between EC and non-EC endometrium and investigated their clinical relevance to EC. Methods: Twenty-eight EC-affected postmenopausal women undergoing hysterectomy were enrolled. Endometrial microbiome from paired EC and adjacent non-EC tissue samples were detected using 16S rRNA sequencing, and the data were analyzed using R language software. Results: The a diversity and evenness of the endometrial bacterial community significantly increased in EC tissues than those in pericancer tissues (P < 0.05 for all variables). Lactobacillus and Gardnerella were the main bacterial genera present in both EC and adjacent non-EC-invading endometrium, whereas Prevotella, Atopobium, Anaerococcus, Dialister, Porphyromonas, and Peptoniphilus were more commonly enriched in the EC endometrium (corrected P < 0.05 for all variables). Finally, the abundance of some observed endometrial bacteria was associated with clinical aspects, particularly the vaginal pH, vaginal Lactobacillus abundance, and EC clinical stage. Conclusions: Paired EC and adjacent non-EC endometrium harbor different endometrial microbiota, and the functional bacteria residing in the endometrium are clinically relevant but require further investigation.