Disruption of intestinal bacteria has had profound and lasting effects, making cancer more aggressive – ScienceDaily

Melanie Rutkowski, PhD, of the UVA Department of Microbiology, Immunology and Cancer Biology, discovered that disrupting the mouse microbiome made bad cancer with positive hormone receptors more aggressive. The modification of the microbiome, the collection of microorganisms living in the intestines and elsewhere, has had dramatic effects on the body, causing the cancer to spread.

"When we disrupted the balance of the microbiome in mice by chronically treating them with antibiotics, this resulted in systemic inflammation and in the bad tissue," she said. "In this inflamed environment, tumor cells were much more likely to disseminate tissue in the blood and lungs, constituting a major metastasis site for hormone-receptor positive bad cancer."

Positive hormone receptor bad cancer

Most bad cancers – 65% or more – are hormone receptor positive. This means that their growth is fed 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 bad and into other parts of the body (a process called metastasis) is a major challenge in this area. It depends mainly on clinical characteristics at the time of diagnosis. Early metastases are influenced by various factors, Rutkowski explained. "One of them has a high level of [immune] cells called macrophages present in the tissue, "she said. Studies have also shown that an increase in the amount of structural collagen protein in the tissue and tumor also results in an increase in bad cancer metastasis. "

Having an unhealthy microbiome before bad cancer increased both and the effect was powerful and sustained. "The disturbance of the microbiome has resulted in long-term inflammation in the tissues and in the tumor environment," Rutkowski said. "These findings suggest that having an unhealthy microbiome and the changes that occur in the tissues and that are linked to an unhealthy microbiome may be an early predictor of invasive or metastatic bad cancer." The microbiome contributes to increased invasion and at a higher incidence of metastatic diseases. "

Maintain a healthy microbiome

Although Rutkowski used powerful antibiotics to disrupt the natural intestinal bacteria of mice, she pointed out that antibiotics are not dangerous and should not be avoided by women with bad cancer or by anyone who needs it to treat infections. After all, mice are not people and much more research is needed to determine whether there is a link between the use of chronic antibiotics and cancer outcomes. For this study, antibiotics were only one way to an end, a simple way to create a long-term imbalance for the microbiome, similar to what individuals can experience with chronically unhealthy microbiomes . The effect was much, much more exaggerated than would occur in a person taking a regular antibiotic treatment, or even several cycles.

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

Although she is an oncology researcher rather than a doctor, Ms. Rutkowski noted that some things are generally accepted to promote a healthy microbiome. "A healthy diet, rich in fiber, accompanied by exercise, sleep, are all factors that contribute to overall positive health," she said. "If you do all that, in theory, you should have a healthy microbiome, and that, we think, is very much badociated with a long-term, positive outcome for bad cancer."