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Vaginal microbiota composition linked to ovarian cancer risk

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Further research needed

One question that remains from the current study is whether the human microbiota is an important factor in the pathogenesis and development of ovarian cancer.

Currently, there has been no evidence directly linking the composition of the human microbiota to ovarian cancer. As a result, causation has yet to be established by means of randomized studies, since the majority of completed studies have been cross-sectional in nature. As a highly heterogeneous condition, several factors may be involved, including a variety of host reproductive, genetic, microbiota, and lifestyle considerations.

While various mechanisms have been proposed, other less familiar causes could also be implicated. For example, Dr. Nené and colleagues found an association between BRCA1 mutation carriers younger than 50 years of age and the presence of community type O microbiota, while only 10%-15% of females with incident ovarian cancers exhibit this mutation. These findings accentuate the complexities of ovarian cancer pathophysiology.

Despite the suggested benefits of probiotic therapy, there remains a call for systems biology strategies in ovarian cancer research. In a similar manner, the human microbiota needs to be considered in future research.

Hans Verstraelen, MD, MPH, PhD, is affiliated with Ghent University and the Ghent University Hospital in Belgium. Dr. Verstraelen reported no competing interests. These comments are adapted from his editorial (Lancet Oncol. 2019 Jul 9. doi: 10.1016/ S1470-2045[19]30340-7 ).


Women with epithelial ovarian cancer or BRCA1 mutational status were more likely to present with a community type O cervicovaginal microbiota relative to age-matched controls, according to a case-control analysis.

The results suggest that the composition of the cervicovaginal microbiome may have a key role in ovarian carcinogenesis. In addition, dysbiosis could be an important risk factor in women at high risk for the disease.

“Our aim was to establish whether women with, or at risk of developing, ovarian cancer have an imbalanced cervicovaginal microbiome,” wrote Nuno R Nené, PhD, of University College London, and colleagues. Their report is in The Lancet Oncology.

The researchers conducted a case-control study of adult females located in five European countries. Study participants were divided into two sets that consisted of 176 females with ovarian cancer and 109 females with a BRCA1 mutation, but without a diagnosis of ovarian cancer.

The two sets were matched with a combination of healthy controls and others with benign gynecologic disorders. Each cohort was split into females younger than 50 years and those over age 50.

In the analysis, females younger than 50 years with ovarian cancer were more likely to have a community type O microbiota relative to age-matched controls (adjusted odds ratio, 2.80; P = .020).

In the BRCA set, women with a BRCA1 mutation who were younger than 50 years were also more likely to present with a community type O microbiota than were wild type age-matched controls (adjusted odds ratio, 2.79; P = .012).

“In both sets, we noted that the younger the participants, the stronger the association between community type O microbiota and ovarian cancer or BRCA1 mutation status,” the researchers wrote.

They acknowledged that a key limitation of the study was the homogenous patient population. Since the vaginal microbiome can vary based on ethnicity, the generalizability of the results may be limited.

“Our findings warrant further detailed analyses of the vaginal microbiome, especially in high-risk women,” they concluded.

The study was funded by the EU’s Horizon 2020 Research and Innovation Programme, the EU’s Horizon 2020 European Research Council Programme, and The Eve Appeal. The authors reported financial affiliations with Eurofins, AstraZeneca, Biocad, Clovis, Pharmamar, Roche, Takeda, and Tesaro.

SOURCE: Nené NR et al. Lancet Oncol. 2019 Jul 9. doi: 10.1016/S1470-2045(19)30340-7.

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