Women with family history of breast cancer should consider genetic testing

The thoughtful and well- written piece by actor Angelina Jolie in yesterday's New York Times has stimulated worldwide discussion on breast cancer.

Jolie underwent a double mastectomy because she is a carrier of a gene that is known to predispose a small number of women to breast cancer.

She has the BRCA1 gene, which in her case meant she had an 87 per cent lifetime risk of developing a breast tumour and a 50 per cent chance of developing cancer of the ovaries in the future. By having both her breasts removed as a prophylactic measure, Jolie’s risk of having breast cancer has dropped to just 5 per cent.

While the risk of developing ovarian or breast cancer in women with either the BRCA1 or BRCA2 genes varies from individual to individual, on average that risk is of the order of 65 per cent. It means women identified with these genes must face a challenging decision: whether to undergo mastectomy and/or removal of their ovaries to reduce their risk of developing cancer.

These particular genes do not cause many cases of breast cancer, but where there is a strong family history of the disease, it is important that women consider being tested for a genetic mutation. Ideally, the genes are identified in the first person in the family to develop breast cancer and doctors will then advise other family members to be tested.

Specialist opinion
However, if you are aware that a close relative had breast cancer at a young age or that a male relative had breast cancer, this is something to bring to the attention of your family doctor, who may refer you for a specialist opinion and possibly a blood test.

Tests are carried out by the National Centre for Medical Genetics in Crumlin hospital following referral by a consultant.

Last September, research published in Nature magazine caused excitement in the scientific and medical worlds when it was revealed there were four basic types of breast cancer. Carried out as part of the Cancer Genome Atlas project, the studies analysed tumours from some 825 patients with breast cancer.

Researchers found that in women with the BRCA genes, the cancer cells resembled the cells in the basal layer of skin. More common forms of breast cancer were identified as either Luminal A or Luminal B type cells. The final category was labelled HER2 enriched because the tumours carried extra copies of the HER2 gene that drives the growth of these tumours.

Emphasising the diversity of the disease, researchers found that even within the four major types of breast cancer individual tumours were driven by their own set of genetic changes.