Microbiome affect on cancer studied
DEAR DOCTOR: A friend of mine is about to start immunotherapy for lung cancer. Is there anything she can do to increase the chances that her gut will help her body?
DEAR READER: Your question sends us into the brave new world of precision medicine. Unlike chemotherapy, which targets all of the fast-dividing cells within the body no matter their origin, or radiation, which kills cancer cells by damaging the DNA in all of the cells in its path whether they are healthy or cancer cells, immunotherapy approaches cancer precisely, and at the cellular level. The point isn’t to destroy cancer cells; it’s to disrupt them.
For instance, researchers have designed antibodies that disable cancer cells by targeting specific sites within those cells. They have also created chemo- and radiolabeled antibodies, which deliver microdoses of powerful anti-cancer drugs and radiation to cancer at the cellular level. In an approach known as “adoptive T cell transfer,” a patient’s own immune cells are collected, modified to enhance cancer-fighting properties, and then re-infused.
New research suggests this targeted approach can be bolstered by beefing up a patient’s own gut microbiome, which is the vast collection of microbial communities within us. Although immunotherapy is brilliant in theory, in practice the results have been mixed.
That’s because the immune system is so alert to intruders of any
kind that the presence of the immunotherapy drugs themselves can set it off. Side effects of immunotherapy include rashes, fever, headache, weakness, elevated liver enzymes, low blood cell counts, breathing issues, diarrhea and vomiting. Some reactions can be life-threatening. In exploring avenues to help a patient’s body tolerate immunotherapy, researchers looked to the gut microbiome.
According to two studies in the journal Science, patients who responded best to treatment with a certain class of immunotherapy drugs were those with more diverse and robust microbiomes.
One study, done by researchers in Texas, focused on patients with melanoma. The other, conducted in France, included patients who had undergone a course of antibiotics to deal with lung, bladder and kidney cancer. The French researchers found that patients who had undergone a course of antibiotics to deal with problems like a urinary tract infection had the poorest response to immunotherapy. Several biotech companies also are doing clinical research.
Your friend can improve her microbiome by adding fermented foods and beverages to her diet, eating high-fiber fresh fruits and vegetables, and steering clear of artificial sweeteners and processed foods.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health.