Researchers have discovered nine new genes which are involved in the development of breast cancer, bringing the number of all genes so far associated with the development of breast cancer to 40, according to a study published in Nature.

The researchers analyzed all genes in the genomes of 100 breast cancer cases and discovered that there were different mutated cancer-causing genes in different samples of cancer, suggesting that breast cancer is genetically diverse. This finding is significant for the development of better cancer therapies, as researchers need to understand the consequences of this diversity in order to progress.

Changes in DNA are the driving force for all cancers. Cancer is a result of somatic mutations that individuals acquire during their lifetime. Cancer genes contain driver mutations, a small subset of somatic mutations that drive the development of cancer.

First researcher, Dr Patrick Tarpey, from the Wellcome Trust Sanger Institute remarks:

“Breast cancer is the most common cancer in women. 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.”

The team’s comprehensive genome analyses provide a clearer picture of the driver mutations in breast cancer. The discovery of driver mutations in at least 40 different cancer genes, of which most individual cancers had different combinations of mutated cancer genes led the team to conclude that there is a significant genetic diversity in breast cancer cells. Leading researcher Professor Mike Stratton, Director of the Wellcome Trust Sanger Institute declares:

“In 28 cases we found only a single driver, but the maximum number of driver mutations in an individual cancer was six. 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.”

Professor Andy Futreal, who was the Head of Cancer Genomics at the Wellcome Trust Sanger Institute and who is now an Honorary Faculty Member at the Institute explains:

“One of the most striking things about breast cancer is how it progresses differently in each patient and how each patient responds differently to therapy. Our results can help us to understand these differences.”

According to the team, genomes are marked by years of continuous attacks, which leave mutations scattered though people’s DNA. This most comprehensive study to-date of breast cancer mutations reveals the full diversity of the driving events that prompt normal breast cells to change into breast cancers.

Professor Stratton concludes:

“The picture is certainly more complicated than we would have wanted, but as with many other things knowledge is our strongest weapon. These comprehensive insights reveal the faulty wiring of the cellular circuit board that causes cells to behave as cancers. Understanding our enemy at this level of detail will allow us to take more rational approaches to therapy, to understand why some cancers respond to drugs and others do not, and direct us to new vulnerabilities to be exploited in new treatments.”

Written By Petra Rattue