Researchers describe nine new genes that drive the development of breast cancer in a study published today in Nature. The tally of all genes associated with breast cancer development is taken to 40 thanks to this. The team examined all the genes in the genomes of 100 cases of breast cancer. The mutated cancer-causing genes were different in different cancer samples, indicating that breast cancer is genetically very diverse. Understanding the consequences of this diversity will be important in progressing towards more rational treatment.
Changes to DNA lie behind all cases of cancer. Cancer develops as a result of mutations – called somatic mutations – that are acquired during a person's lifetime. Driver mutations, which occur in cancer genes, are a small subset of somatic mutations that drive the development of cancer.
"Breast cancer is the most common cancer in women," explains Dr Patrick Tarpey, first author from the Wellcome Trust Sanger Institute. "To identify new cancer genes that lead to the development of breast cancer, we searched for driver mutations in over 21,000 genes, and found evidence for nine new cancer genes involved in the development of this cancer."
These genome analyses provide a direct survey of the landscape of driver mutations in breast cancer. The team found driver mutations were present in at least 40 different cancer genes. Most individual cancers had different combinations of mutated cancer genes, demonstrating the substantial genetic diversity in breast cancer.
"In 28 cases we found only a single driver, but the maximum number of driver mutations in an individual cancer was six," says Professor Mike Stratton, lead author and Director of the Wellcome Trust Sanger Institute. "We found that breast cancer can be caused by more than 70 different combinations of mutations.
"If we consider three breast cancers, each with four driver mutations: they might share none of those driver mutations – so each is a different genetic 'animal'. They are different cancers driven by different genes. We need to classify them as carefully as we can. This study is a step towards that goal."
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Our genomes are scarred by decades of continual assault that leave mutations scattered though our DNA. This is the most comprehensive study thus far of mutations in breast cancers, discovering nine new mutated genes that cause breast cancer, and revealing the full diversity of the driving events that convert normal breast cells into breast cancers.
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Source-Eurekalert