Nearly 30 per cent patients with breast cancer gained weight after receiving chemotherapy treatment, suggested a study. Beyond weight gain, chemotherapy is also known to increase the risk of high blood pressure and glucose intolerance, a pre-diabetes condition. Although this is a familiar phenomenon, the mechanisms underlying these processes have not yet been identified. Dr Ayelet Shai initiated the research study. He is Director of Oncology at the Galilee Medical Center, who led the study with Professor Omry Koren, an expert in gastrointestinal bacteria at the Azrieli Faculty of Medicine of Bar-Ilan University. The study conducted by Dr Shai and Prof Koren involved 33 women who were about to begin chemotherapy for breast cancer and gynaecological cancer. The women were weighed once before the treatment, and once again approximately five weeks after treatment began. The study showed that the composition of intestinal bacteria may predict which women will gain weight as a result of chemotherapy. Dr Shai and Prof Koren are currently in the midst of a follow-up study which aims to examine the results in a larger patient population and to examine the microbiome of women at the end of chemotherapy in order to understand the effect of the treatment on bacterial composition.