A new study from researchers at the University of Virginia Cancer Center connects an unhealthy bowel microbiome with breast cancer that can become invasive and spread to other organs more quickly. The results of the study were published in the latest edition of the journal Cancer Research. The study titled "Pre-existing commensal dysbiosis is an intrinsic host regulator of tissue inflammation and dissemination of tumor cells in hormone receptor-positive breast cancer," was supported by an Susan G. Komen bag.
Microbiome in the human intestine. New research from the University of Virginia School of Medicine suggests that a health-damaging microbiome can promote the spread of breast cancer. – Illustration. Credit: Alpha Tauri 3D Graphics / Shutterstock
Lead researcher Melanie Rutkowski of the Department of Microbiology, Immunology and Cancer Biology in her study found that if the intestinal microbiome or microbial content of the intestine of laboratory mice is altered, her hormone receptor positive breast cancer turned more aggressive. This change in the normal flora of the bacteria's health inside the intestines of the mice has altered the nature of the cancer and prepared it to spread to other organs, write the researchers.
The team writes that so far it is not known why some of the hormone receptor positive cancers are more aggressive and invasive compared to others. They analyzed intrinsic host factors, such as the altered intestinal microbiome, termed "commensal dysbiosis," and are associated with the aggressive nature of cancer.
Rutkowski explained: "When we interrupt the microbiome's balance in mice by treating them chronically with antibiotics, this has resulted in systemic inflammation and within the breast tissue. In this inflamed environment, tumor cells were much more capable of spreading tissue into the blood and into the lungs, which is an important site for hormone receptor-positive breast cancer to metastasize. "She said that in the next part of their study they transplanted the unhealthy microbiome from their test mice to other mice with HR positive breast cancer using fecal transplantation. The results were similar among recipient mice, she explained. This has proven the direct effect of the microbiome on the conversion of aggressive breast cancer.
Experts say that hormone receptor-positive cancers or breast cancers that grow under the influence of the female hormones estrogen and progesterone make up about 65% of all breast cancers. These cancers are more responsive to hormone therapy and generally have a good outcome. Rutkowski explained that the way these cancers spread and grow depends on several factors observed at the time of diagnosis. She said: "One of them is to have a high level of [immune] cells called macrophages present in the tissue. "She added," There are also studies that have shown that increased amounts of structural collagen protein in the tissue and tumor also lead to increased metastasis of breast cancer. "
She went on to explain that people with an unhealthy intestinal microbioma have an increased inflammation of the intestine. This effect is often sustained and powerful, she said. She added: "Disruption of the microbiome resulted in long-term inflammation in the tissue and tumor environment. These findings suggest that having an unhealthy microbiome and changes in tissue related to an unhealthy microbiome may be early predictors of invasive or metastatic breast cancer. Finally, based on these findings, we would speculate that a health-damaging microbiome helps to increase invasion and increase the incidence of metastatic disease. "
Experts warn that this is an animal study and can not be extrapolated in humans. Rutkowski warns that the team used antibiotics to kill the gut microbes, but all antibiotics are not bad and, when necessary, should be taken by women who have breast cancer. This study should not lead women with breast cancer to avoid all antibiotics, experts warn. The team adds that more research is needed to prove the connection between the continued use of antibiotics and the spread of breast cancer. This study was performed in mice genetically modified with HR positive breast cancer. The actual image among humans may be different, the team explains.
Doctors and the research team add that this study shows that if the intestinal microbiome can be maintained, there may be a positive result in women with breast cancer. Rutkowski said that this study highlights the importance of having a healthy intestinal microbiome. She added that many aspects of good health are associated with a healthy bowel. This study reveals another reason to keep a healthy microbiome.
Rutkowski concluded: "A healthy diet, high in fiber, along with exercise, sleep – all these things that contribute to overall positive health. If you do all these things in theory, you should have a healthy microbiome. And this, we think, is very much associated with a favorable long-term outcome for breast cancer. "
Pre-existing commensal dysbiosis is an intrinsic host regulator of tissue inflammation and the spread of tumor cells in hormone receptor-positive breast cancer, Claire Buchta Roseana, Raegan R Bostic, Joshua CM Ferey, Tzu-Yu Feng, Francesca N Azar , Kenneth S Tung, Mikhail G Dozmorov, Ekaterina Smirnova, Paula D. Bos and Melanie R Rutkowski, DOI: 10.1158 / 0008-5472.CAN-18-3464, http://cancerres.aacrjournals.org/content/early/2019 / 05/07 / 0008-5472.CAN-18-3464