In addition to weight gain, chemotherapy is known to increase the risk of high blood pressure and glucose intolerance, a prediabetes condition. Although this is a well-known phenomenon, the mechanisms underlying these processes have not yet been identified. Dr. Ayelet Shai initiated the research study. He is director of oncology at Galilee Medical Center and led the study with Professor Omry Koren, an expert in gastrointestinal bacteria at the Azrieli Faculty of Medicine at Bar Ilan University.
Dr. Shai said that symptoms she observed as an oncologist prompted her to initiate the study: “In my clinical work with women who have recovered from breast and gynecological tumors, I have seen many of them after Treatment have gained weight and have difficulty returning to their original weight. When reading the medical literature on the link between the microbiome and obesity in people without cancer, I found it interesting to see if the microbiome of patients was one of the causes Obesity and other metabolic changes is up, “she said. At the Dr. Shai and Prof. Koren enrolled 33 women who were about to begin chemotherapy for breast cancer and gynecological cancer. The women were weighed once before treatment and again approximately five weeks after treatment started. A stool sample was used prior to treatment to genetically characterize the microbiome of each of the women. Nine of the women saw weight gain that was defined as significant (3 percent or more). The microbiome of these women showed less diversity of gut bacteria and different strains of bacteria than that of the women who did not gain weight.
The study showed that the composition of gut bacteria can predict which women will gain weight as a result of chemotherapy. In addition, when the gut microbiota of women who had gained weight were transferred to germ-free mice, they developed glucose intolerance and signs of chronic inflammation were seen in their blood. These results suggest that bacteria are partially responsible for metabolic changes that lead to weight gain after chemotherapy. “We have shown for the first time that the pre-treatment microbiome of patients who have gained weight after chemotherapy is different from the microbiome of patients who have not gained weight and that a fecal transplant is different from those who have gained weight , leads to glucose intolerance and adverse lipid changes and inflammatory changes in germ-free mice, “said Prof. Koren. These results suggest that the gut microbiome mediates metabolic changes in women treated by chemotherapy. In addition, the composition of the gut microbiome before chemotherapy can predict which patients will gain weight after treatment.
Dr. Shai and Prof. Koren are currently in a follow-up study aimed at examining the results in a larger patient population and examining the microbiome of women at the end of chemotherapy to understand the effect of treatment on bacterial composition. The researchers also plan to study the effect of chemotherapy on obesity in germ-free mice after a fecal transplant. If the results obtained in the first study are repeated, a stool test for women may be considered before starting treatment so that the patient knows if there is a risk of weight gain. On the occasion of the Breast Cancer Education Month in October, Dr. Shai: “We hope that in the future we will be able to identify those women who are at risk of weight gain through a simple examination and possibly even suggest ways to prevent this phenomenon.” (ANI)