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Link Between Gut Bacteria and Breast Cancer

This month more research from researcher JJ Goedert about gut microbes in postmenopausal women and breast cancer. Very suggestive research was published September 2014 about the possibility of increasing a person's gut bacteria diversity to lower breast cancer risk. And even earlier research found that the human breast has a microbiome (community of microbes) that is different in healthy breasts as compared to cancerous breasts.

Now JJGoedert and others investigated whether the gut microbiota differed in 48 postmenopausal breast cancer case patients (before treatment) as compared to 48 control patients (women without breast cancer). The average age of both groups was 62 years.The researchers analyzed the estrogens in the women's urine and the bacterial diversity in fecal samples using modern genetic analysis (such as 16S rRNA sequencing). They found in this study that postmenopausal women with breast cancer had lower gut bacteria diversity and somewhat different composition of gut bacteria as compared to women without breast cancer. They also said that what this means is unknown, that is,"whether these affect breast cancer risk and prognosis is unknown." Some differences in gut bacteria composition: women with breast cancer had lower levels of Clostridiaceae, Faecalibacterium, and Ruminococcaceae; and they had higher levels of Dorea and Lachnospiraceae.

Excerpt is from the Journal of the National Cancer Institute:

Investigation of the association between the fecal microbiota and breast cancer in postmenopausal women: a population-based case-control pilot study.

We investigated whether the gut microbiota differed in 48 postmenopausal breast cancer case patients, pretreatment, vs 48 control patients. Microbiota profiles in fecal DNA were determined by Illumina sequencing and taxonomy of 16S rRNA genes. Estrogens were quantified in urine....  Compared with control patients, case patients had statistically significantly altered microbiota composition  and lower α-diversity. Adjusted for estrogens and other covariates, odds ratio of cancer was 0.50 per α-diversity tertile. Differences in specific taxa were not statistically significant when adjusted for multiple comparisons. This pilot study shows that postmenopausal women with breast cancer have altered composition and estrogen-independent low diversity of their gut microbiota. Whether these affect breast cancer risk and prognosis is unknown.