New genetic link to inherited breast cancer found

A team from the Institute of Cancer Research in London have found that women carrying a faulty version of the Gene ATM, a DNA repair gene, have an increased risk of contracting breast cancer. They found that the risk rises from one in 12 in the general population to one in six in affected women.

It has been known for some time that carrying particular versions of the BRCA1 and BRCA2 genes increases women's risk of inherited breast cancer, this new research shows that there is also an increased risk of cancer from the faulty ATM gene. The genetic fault in ATM affects between 0.5 and one per cent of the population and between five and 10 per cent of all breast cancers are believed to have an inherited genetic basis. Currently the only genes routinely screened for in those with a family history of breast cancer are the BRCA genes. This research suggests that ATM may in future be added to screening programmes. Over 40,000 women in the UK are diagnosed with breast cancer each year.

The scientists took 433 breast cancer patients who had a family history of the disease but normal copies of BRCA1 and BRCA2, and compared them with 521 healthy women. They found that the cancer sufferers had twelve faults in the ATM gene compared to only two in the non-suffering women. Detailed statistical analysis allowed the team to calculate the risk from the faulty gene as more than doubling the women's cancer susceptibility by age 70. ATM, like the BRCA genes, is involved in DNA repair, if it is faulty and unable to correct mutations in normal cells these may become cancerous.

The paper, published in Nature Genetics, warns that more research needs to be carried out before the full impact of the discovery is understood. It is not thought that the extra risk from ATM would warrant preventative surgery or taking medication before cancer is discovered, as sometimes happens with women at risk from faulty BRCA genes. Professor Nazneen Rahman, lead researcher in the study, commented that 'our study provides strong evidence for the first time that damaged ATM genes definitely have a moderate effect on breast cancer risk in a small number of women', adding 'women who carry these genetic faults could benefit from targeted screening and new treatments in the future'. The work was funded by Cancer Research UK, the Institute of Cancer Research and Breast Cancer Campaign.