A major new study – the largest of its kind ever undertaken – has been hailed as a milestone in the understanding of breast cancer and its causes.

The new study, published in Nature, provides a “near-perfect picture” of the genetic processes that lead to breast cancer and opens up new possibilities for treatment and prevention of the disease.

Led by the Sanger Institute in Cambridge and involving dozens of researchers, the study analysed the entire genome sequence in 560 breast cancers, and discovered that out of the total 20,000 genes in the human genome “93 protein-coding cancer genes carried probable driver mutations”. These are the genes that, if mutated, will cause a normal breast cell to turn into a cancer cell, ultimately forming a tumour.

The report concluded: “A comprehensive perspective on the somatic genetics of breast cancer is drawing closer ...Additional infrequently mutated cancer genes probably exist. However, the genes harbouring the substantial majority of driver mutations are now known.” In other words, the mechanism by which breast cancer comes about, in almost all cases, is understood.

This opens up new possibilities for drugs and other treatments that specifically target these problematic genes. There are already drugs in use that use this targeted approach – Herceptin is one example – and which have been shown to be effective.

According to figures from Cancer Research UK, 2013 saw 53,696 cases of breast cancer in the UK, with 11,433 deaths in 2014 resulting from the disease. Breast cancer has a 78% survival rate, making it one of the most successfully treated cancers – but 27% of cases in the UK are still regarded as “preventable”.

Gordon Wishart, Professor of Cancer Surgery and Chief Medical Officer of Check4Cancer, comments:“This is a significant moment in the history of research into breast cancer, which should have equal significance for the detection and treatment of the disease. Breast cancer has a very high public profile – probably the highest of any cancer. Thanks in part to the interest that this high level of awareness attracts, it has also long been one of the most deeply researched and understood.

“Far from making it an isolated case, however, what this shows is that the same may be possible for other forms of cancer, and that the time may come when we have a similarly comprehensive understanding of the processes of all the main cancers. Breast cancer has seen huge advances in terms of risk assessment, detection and treatment in recent years and as a result and has become one of the real success stories. This not only shows we can do even better with breast cancer, but that if we have the necessary resources and apply them correctly, we can ultimately achieve similar successes across the board. If we did, this would save tens of thousands of lives.”