Seventy-two genetic changes that can lead to breast cancer have been discovered by an international team that included researchers from Clalit Health Services and the Technion-Israel Institute of Technology in the largest study of the disease ever conducted.The study, just published in Nature and Nature Genetics, provides new information on the mechanisms that cause the malignancy. Besides Israelis, the study included scientists from the United States, Canada, Australia, Japan and a large number of Western European countries.The study identified 65 genetic changes that expose women to breast cancer, along with seven other changes that expose a specific group of women to hormone-receptor-negative forms of the disease that do not respond to hormone therapy. The genetic component in the risk of breast cancer is comprised of relatively rare changes in genes, such as BRCA1 / BRCA2 that carry a high risk of disease, and a long list of common changes, each making only a relatively small contribution to risk. The new, large-scale study doubles the currently known number of subtle genetic changes associated with breast cancer, thus improving the understanding of its causes and the chances of finding new treatment pathways, the researchers said.The findings are the result of a huge international effort that involved an investigation of some 275,000 women worldwide, of whom 146,000 had breast cancer. It was part of a consortium called OncoArray led by Cambridge University researchers and headed by Prof. Douglas Easton of the Center for Cancer Genetic Epidemiology at the University of Cambridge.According to Prof. Gad Rennert, director of Clalit’s National Center for Cancer Control and the study’s lead researcher, the main contribution of the research is in identifying additional biological pathways whose disruption is linked to the risk of breast cancer and that will lead to the development of new innovative drugs for fighting the disease.Clalit is currently involved in advanced research on changes typical in the Israeli population – among specific ethnic groups of both Jews and Arabs – to understand the causes of breast cancer and to promote the chances of developing new drugs specific to them. “At the same time, an effort has been made to identify typical changes in a particular type of breast cancer, which is currently common to at least four different molecular types,” said Rennert.He added that the new findings do not detract from the large and central importance of the typical mutations found in Israeli populations in the known BRCA1/2 genes as founder mutations. Because of the high prevalence of these mutations, especially among Ashkenazim, it is important for every woman diagnosed with breast or ovarian cancer – and women (or men) who do not have those diseases but whose family members do – to get a simple blood test for the presence of these mutations.For testing and genetic counseling, contact the genetic units in most of hospitals in Israel or call Clalit’s National Cancer Family Counseling Service at 04-825-0460.