The Role of the Endometrial Microbiota in Endometrial Cancer: A Systematic Review of the Literature

Background: Endometrial cancer is currently the sixth most frequent cancer in women, and scientific research is focusing on the search for particular features of the endometrium that may explain a further predisposition to the onset of endometrial cancer, aimed at improving knowledge of the pathogenetic factors of this disease. The aim of our review is to analyze in detail the results of the literature on the endometrial microbiota in patients with endometrial cancer and to investigate its role. Methods: We performed our research on the Pubmed, Web of Science, and Scopus databases. We searched up to December 2023 and considered manuscripts published from 2000. Only articles in English were included in the search. We excluded studies in which the endometrial microbiota were collected through the vagina or cervical canal. Results: We included in our review a total of five manuscripts at the end of the screening process, and the total number of patients involved was 190. Four studies considered only post-menopausal patients, while one study considered both pre- and post-menopausal patients. In all studies, the microbiota analysis was derived from a post-hysterectomy biopsy. From our review, it emerged that Bacteroidetes, Actinobacteria, Firmicutes, and Proteobacteria are the most represented bacteria in patients with endometrial cancer. These are both Gram-positive and Gram-negative, but predominantly anaerobic bacteria. Conclusions: The reduced microbial diversity and the presence of specific bacteria is often associated with endometrial cancer. Further work on larger population samples, and on healthy women and those affected by endometrial carcinoma, is needed to understand how the endometrial microbiota changes and influences the development of the tumor and whether intervening in the changes in the microbiota will have a therapeutic impact on endometrial carcinoma.