Researchers from Bar-Ilan University and the Galil Medical Center researchers Prof. Omri Koren and Dr. Ayelet Shay believe that it will be possible to test prevention using appropriate probiotics
Chemotherapy may save lives, but it comes at the cost of many side effects. One of the well-known and common symptoms among breast cancer patients is weight gain. A new study points to the connection between the population of intestinal bacteria and the phenomenon.
In recent years, many studies shed light on the connection between the microbiome - the population of intestinal bacteria that exists in the body of each and every one of us - and between various health and disease states. The composition of the microbiome and the balance between the bacterial strains that it includes have extensive effects on our mental and physical functioning. A new study indicates a link between gut bacteria and weight gain among breast cancer patients treated with chemotherapy. The study was initiated by Dr. Ayelet Shai, director of the oncology department at the Galilee Medical Center, and led it together with Prof. Omri Koren from the Azrieli Faculty of Medicine of Bar-Ilan University. The research findings were published in the prestigious journal BMC Medicine.
Dr. Shai said that phenomena she witnessed as an oncologist led her to initiate the research: "In my clinical work with women recovering from breast and gynecological tumors, I saw many women who gained weight following the treatments, and had difficulty returning to their previous weight. The phenomenon is also known from the medical literature. When I read about the connection between the microbiome and obesity in people without cancer, I thought it would be very interesting to check whether the patients' microbiome is one of the causes of obesity and other metabolic changes."
According to the professional literature, about 30% of breast cancer patients who receive chemotherapy gain weight, but it is not known why some women gain weight and others do not. Beyond weight gain, it is known that chemotherapy treatment also increases the risk of high blood pressure and glucose intolerance, which is a pre-diabetic condition. Although this is a known phenomenon, the mechanisms underlying these processes have not been defined so far.
33 women who were about to start chemotherapy for breast cancer and gynecological cancer participated in Dr. Shay's and Prof. Koren's research. The women were weighed once before the treatment, and again about five weeks after it started. It was found that nine of the study participants gained weight to an extent that was defined as significant (3% or more). Before the treatment, a stool sample was also taken, which was used for the genetic characterization of the microbiome in each of the women. After a few weeks of chemotherapy, the composition of the microbiome was again examined, and it was found to have changed significantly among the women who gained weight. The change was reflected in a smaller variety of gut bacteria and bacterial strains that were different than those found in the women who did not experience weight gain. One of the important research findings is that in the women who gained weight, the microbiome was characterized by a low diversity between the bacteria even before the start of the treatment.
The study showed that the composition of gut bacteria may predict which of the women undergoing chemotherapy will gain weight. On top of that, when the gut bacteria of the women who gained weight were transplanted into the guts of sterile mice (that is, without their own microbiome), the mice developed sugar intolerance and signs of a chronic inflammatory condition were found in their blood. These findings imply that the bacteria are part of the causes of the metabolic changes that lead to weight gain following chemotherapy treatment.
Dr. Shai and Prof. Koren are currently in the middle of a follow-up study, the purpose of which is to test the phenomena they found in a larger patient population and to test the microbiome of the women at the end of the treatment, in order to understand the effect of the treatment on the composition of the bacteria. In addition to this, the researchers plan to test the effect of chemotherapy on obesity in sterile mice that underwent fecal transplantation from women, and to see if there is a difference between mice whose digestive system was transplanted with feces from women who gained weight compared to mice that received feces from women who did not gain weight.
If the results obtained in the initial study are indeed repeated, Dr. Shay points out, it would be possible to think about a stool test for women before starting treatment, so that the patient would know if she is at risk of gaining weight. In addition, it will be possible to check prevention through an adapted diet and even adapted probiotics.
"We hope that in the future we will be able to locate with a simple test the women who are at risk of weight gain and perhaps even offer ways to prevent this phenomenon," said Dr. Shay and Prof. Koren.
More of the topic in Hayadan:
- A new approach to breast cancer treatment: blocking inflammatory pathways that support the tumor and its metastases
- Discovery of gene properties will allow treatment against a particularly violent type of breast cancer
- Holocaust survivors who suffered from Holocaust-related post-traumatic stress disorder are more likely to develop breast cancer during their lifetime
