Case for a role of the microbiome in gynecologic cancers: Clinician's perspective

Abstract

In this review, we aimed to provide insight into the microbiome and its association with endometrial and ovarian cancer and their risk factors. We reviewed the literature focusing on the relationship between the microbiome and cancer, as well as the relationship between gynecologic diseases and cancers. The human body contains different kinds of microorganisms in various body parts, which is termed the microbiome. The number of microorganisms that live in and on the human body is greater than that of the human germ and somatic cells by 10-fold. The relationship between a human and their microbiome is complex; it is also one of the most important components of homeostasis. Impairment of microbiome-host homeostasis has been associated with obesity, several cancers, preterm labor, inflammatory and allergic conditions and neurodevelopmental disorders. Direct and strong causal relationships have been established for several cancers and microorganisms, such as gastric lymphoma and Helicobacter pylori infection. Interestingly, eradication of the infectious agents has also been shown to be therapeutic. The association between cancer and the microbiome, however, is more complicated than a 1 bacteria-1 cancer model, and a shift in a healthy microbiome can result in various cancers via inflammation, change in microenvironment or DNA-damaging toxins. The human microbiome is an integral part of homeostasis. Understanding the mechanisms that cause dysbiosis will enable us to elucidate the pathways that result in malignancy and investigate new treatment modalities.

Association between the cervicovaginal microbiome, BRCA1 mutation status, and risk of ovarian cancer: a case-control study

“…First, an analysis24 of the microbiota of ovarian cancer tissue samples and matched non-cancerous tissue showed that two bacterial phyla, namely Proteobacteria and Firmicutes, were predominant in the cancer samples but not in the control samples. Second, inflammation caused by such agents as Proteobacteria and Firmicutes, and the subsequent release of bacterial toxins such as colibactin and cytolethal distending toxin, could directly damage the cellular DNA by causing doublestranded breaks and thereby activating the DNA damage checkpoint pathway 25. Third, the protective mechanism of interventions that reduce ovarian cancer risk could be mediated, at least partly, by modulation of the microbiota.…”

The differential distribution of bacteria between cancerous and noncancerous ovarian tissues in situ

“…c The relative abundance of Anoxynatronum sibiricum (Control group: n = 10, cancer group: n = 6, P = 0.034, Mann-Whitney U test). d The relative abundance of Methanosarcina vacuolata (Control group: n = 10, cancer group: n = 6, P = 0.001, Mann-Whitney U test) mechanisms that tubal ligation impairs circulation of bacteria that are associated with ovarian cancer risk between the lower and upper genital tract [26]. Second, the bacteria in the upper female reproductive tract, including the ovaries, may be endosymbiotic and separated from other bacteria and the outside environment [4].…”

The Role of the Cervicovaginal Microbiome on the Genesis and as a Biomarker of Premalignant Cervical Intraepithelial Neoplasia and Invasive Cervical Cancer

“…Gynecological cancers have also been associated with microbiome constitution [41]. A study compared the microbiomes from different sites of the female reproductive tract (vaginal, uterine, Fallopian tubes, and ovarian samples) between women with endometrial cancer, endometrial hyperplasia, or benign uterine alterations.…”