Nav: Home

Unhealthy gut promotes spread of breast cancer, study finds

June 10, 2019

An unhealthy, inflamed gut causes breast cancer to become much more invasive and spread more quickly to other parts of the body, new research from the University of Virginia Cancer Center suggests.

Melanie Rutkowski, PhD, of UVA's Department of Microbiology, Immunology and Cancer Biology, found that disrupting the microbiome of mice caused hormone receptor-positive breast cancer to become more aggressive. Altering the microbiome, the collection of microorganisms that live in the gut and elsewhere, had dramatic effects in the body, priming the cancer to spread.

"When we disrupted the microbiome's equilibrium in mice by chronically treating them antibiotics, it resulted in inflammation systemically and within the mammary tissue," she said. "In this inflamed environment, tumor cells were much more able to disseminate from the tissue into the blood and to the lungs, which is a major site for hormone receptor-positive breast cancer to metastasize."

Hormone Receptor-Positive Breast Cancer

Most breast cancers - 65 percent or more - are hormone receptor positive. That means their growth is fueled by a hormone, either estrogen or progesterone. The good news is that these types of cancers are likely to respond well to hormone therapy.

Predicting whether such cancers will spread beyond the breast to other parts of the body (a process called metastasis) is a major challenge within the field, and is primarily driven by clinical characteristics at the time of diagnosis. Early metastasis is affected by a variety of factors, Rutkowski explained. "One of them is having a high level of [immune] cells called macrophages present within the tissue," she said. "There have also been studies that have demonstrated that increased amounts of the structural protein collagen in the tissue and tumor also lead to increased breast cancer metastasis."

Having an unhealthy microbiome prior to breast cancer increased both, and the effect was powerful and sustained. "Disrupting the microbiome resulted in long-term inflammation within the tissue and the tumor environment," Rutkowski said. "These findings suggest that having an unhealthy microbiome, and the changes that occur within the tissue that are related to an unhealthy microbiome, may be early predictors of invasive or metastatic breast cancer. Ultimately, based upon these findings, we would speculate that an unhealthy microbiome contributes to increased invasion and a higher incidence of metastatic disease."

Maintaining a Healthy Microbiome

While Rutkowski used powerful antibiotics to disrupt the mice's natural gut bacteria, she emphasized that antibiotics are not dangerous and should not be avoided by women with breast cancer or anyone who needs them to treat infections. Mice, after all, are not people, and substantially more research needs to be done to define whether an association exists between chronic antibiotics usage and cancer outcome. For this study, the antibiotics were only a means to an end, a simple way to create a long-term imbalance to the microbiome, similar to what individuals may experience with chronically unhealthy microbiomes. The effect was far, far more exaggerated than would occur in a person taking a normal course of antibiotics, or even multiple rounds.

Thanks in part to Rutkowski's research, doctors eventually may be able to manipulate the microbiome to benefit patients with breast cancer. But the key message for now, Rutkowski said, is the importance of a healthy microbiome. The finding adds to the growing evidence demonstrating that a healthy microbiome is vital for many aspects of good health.

While she is a cancer researcher rather than a medical doctor, Rutkowski noted there are things that are generally accepted to promote a healthy microbiome. "A healthy diet, high in fiber, along with exercise, sleep - all of those things that contribute to positive overall health," she said. "If you do all of those things, in theory, you should have a healthy microbiome. And that, we think, is very much associated with a favorable outcome in the long term for breast cancer."
-end-
Breast Cancer Findings Published

The researchers have published their findings in the journal Cancer Research. The study's authors were Claire Buchta Rosean, Raegan R. Bostic, Joshua C.M. Ferey, Tzu-Yu Feng, Francesca N. Azar, Kenneth S. Tung, Mikhail G. Dozmorov, Ekaterina Smirnova, Paula D. Bos and Rutkowski.

The research was supported by Susan G. Komen, grant CCR17483602.

To keep up with the latest medical research news from UVA, subscribe to the Making of Medicine blog at http://makingofmedicine.virginia.edu.

University of Virginia Health System

Related Breast Cancer Articles:

Breast cancer: AI predicts which pre-malignant breast lesions will progress to advanced cancer
New research at Case Western Reserve University in Cleveland, Ohio, could help better determine which patients diagnosed with the pre-malignant breast cancer commonly as stage 0 are likely to progress to invasive breast cancer and therefore might benefit from additional therapy over and above surgery alone.
Partial breast irradiation effective treatment option for low-risk breast cancer
Partial breast irradiation produces similar long-term survival rates and risk for recurrence compared with whole breast irradiation for many women with low-risk, early stage breast cancer, according to new clinical data from a national clinical trial involving researchers from The Ohio State University Comprehensive Cancer Center - Arthur G.
Breast screening linked to 60 per cent lower risk of breast cancer death in first 10 years
Women who take part in breast screening have a significantly greater benefit from treatments than those who are not screened, according to a study of more than 50,000 women.
More clues revealed in link between normal breast changes and invasive breast cancer
A research team, led by investigators from Georgetown Lombardi Comprehensive Cancer Center, details how a natural and dramatic process -- changes in mammary glands to accommodate breastfeeding -- uses a molecular process believed to contribute to survival of pre-malignant breast cells.
Breast tissue tumor suppressor PTEN: A potential Achilles heel for breast cancer cells
A highly collaborative team of researchers at the Medical University of South Carolina and Ohio State University report in Nature Communications that they have identified a novel pathway for connective tissue PTEN in breast cancer cell response to radiotherapy.
Computers equal radiologists in assessing breast density and associated breast cancer risk
Automated breast-density evaluation was just as accurate in predicting women's risk of breast cancer, found and not found by mammography, as subjective evaluation done by radiologists, in a study led by researchers at UC San Francisco and Mayo Clinic.
Blood test can effectively rule out breast cancer, regardless of breast density
A new study published in PLOS ONE demonstrates that Videssa® Breast, a multi-protein biomarker blood test for breast cancer, is unaffected by breast density and can reliably rule out breast cancer in women with both dense and non-dense breast tissue.
Study shows influence of surgeons on likelihood of removal of healthy breast after breast cancer dia
Attending surgeons can have a strong influence on whether a patient undergoes contralateral prophylactic mastectomy after a diagnosis of breast cancer, according to a study published by JAMA Surgery.
Young breast cancer patients undergoing breast conserving surgery see improved prognosis
A new analysis indicates that breast cancer prognoses have improved over time in young women treated with breast conserving surgery.
Does MRI plus mammography improve detection of new breast cancer after breast conservation therapy?
A new article published by JAMA Oncology compares outcomes for combined mammography and MRI or ultrasonography screenings for new breast cancers in women who have previously undergone breast conservation surgery and radiotherapy for breast cancer initially diagnosed at 50 or younger.
More Breast Cancer News and Breast Cancer Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Uncharted
There's so much we've yet to explore–from outer space to the deep ocean to our own brains. This hour, Manoush goes on a journey through those uncharted places, led by TED Science Curator David Biello.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 2: Every Day is Ignaz Semmelweis Day
It began with a tweet: "EVERY DAY IS IGNAZ SEMMELWEIS DAY." Carl Zimmer – tweet author, acclaimed science writer and friend of the show – tells the story of a mysterious, deadly illness that struck 19th century Vienna, and the ill-fated hero who uncovered its cure ... and gave us our best weapon (so far) against the current global pandemic. This episode was reported and produced with help from Bethel Habte and Latif Nasser. Support Radiolab today at Radiolab.org/donate.