September is Ovarian Cancer Awareness Month. In a recent study, women with lower levels of protective bacteria in their cervicovaginal microbiota were more likely to carry the BRCA1 mutation, or already have Ovarian Cancer. This study is the first case-control analysis of the cervicovaginal microbiome in women with ovarian cancer and in women at high risk for ovarian cancer. Read the article below for more information.
Women under the age of 50 who have been diagnosed with ovarian cancer or carry the BRCA1 mutation that increases ovarian cancer risk were found to have lower levels of protective bacteria in their cervicovaginal microbiota when compared with healthy controls and nonmutation carriers.
The finding comes from a case-control study published online July 9 in the Lancet Oncology.
The fact that the microbiota was deficient in protective lactobacilli species in women with or at risk for ovarian cancer suggests the reduced prevalence might be causal, researchers speculate.
However, they add it is too early to say if restoring the cervicovaginal microbiota with a probiotic suppository might lower the risk.
In an accompanying commentary, editorialist Hans Verstraelen, MD, PhD, Ghent University, Belgium, is a little more skeptical.
In most populations, the vaginal microbiota of younger women is largely dominated by lactobacilli, and adverse reproductive health outcomes have been observed among women who deviate from the normal vaginal microbiota state, he explains.
“However, the vagina is also a highly dynamic ecosystem,” Verstraelen points out, “and by assessing the microbiota on only one occasion, there is a risk of misclassification bias in the authors’ findings,” he notes.
The more important question to answer is how the vaginal microbiota could promote ovarian cancer, as Verstraelen suggests.
It could be that the vaginal microbiota simply reflects some constellation of extrinsic factors that could be involved in ovarian carcinogenesis.
Smoking, for example, is thought to negatively affect lactobacillus dominance, whereas as oral contraceptives and hormone replacement therapy are thought to promote it, he points out.
“Some researchers have suggested that the vaginal microbiota acts as a so-called microbial seed bank for the upper genital tract,” Verstraelen adds, suggesting a role of the extra-ovarian origins in ovarian cancers.
“Overall, there is no direct evidence that the human microbiota has a key role in cancer causation,” Verstraelen emphasizes.
“But the microbiota needs to be taken into account in future research,” he said, concurring with the study authors.
First Study of Its Kind
“To our knowledge, this study is the first case-control analysis of the cervicovaginal microbiome in women with ovarian cancer and in women at high risk for ovarian cancer,” lead researcher Nuno Nene, PhD, University College London, United Kingdom, and colleagues comment.
“Once the functional relevance of community type O cervicovaginal microbiota [ie, lactobacilli < 50% of species present] in ovarian cancer development has been established, vaginal lactobacilli transplantation in young carriers of germline BRCA1 mutations could become available as a risk reduction measure,” they suggest.