Less than 10% of women with breast cancer will have genetic mutation

Only 5 to 10 per cent of women in Ireland diagnosed with breast cancer will have the genetic mutation that prompted actor Angelina Jolie to undergo major surgery to reduce risk.

Cancer specialists here agreed Jolie had made a sensible choice in deciding to have a double mastectomy because she has a gene that increases her risk of developing breast or ovarian cancer to 87 per cent.

They added, however, that many women at high risk of breast cancer could also choose regular screening as a way to avoid developing the disease.

"Angelina Jolie did exactly the right thing," said Dr Susan O'Reilly, director of the National Cancer Control Programme (NCCP) within the HSE.

Her mother had died young from breast cancer and a genetic test had shown she also had a BRCA1 gene mutation that left her at significantly higher risk of cancer, Dr O'Reilly said.

Relatively infrequent
Yet the mutation is relatively infrequent here and the fact that a woman had a close relative or two older than 50 and diagnosed with breast cancer did not automatically mean they had an inherited genetic risk, she added. "Only between 5 and 10 per cent of women who get breast cancer will have a familial reason," Dr O'Reilly said. "Cancer is a genetic disease but a random genetic occurrence."

Having older family members with the disease was, in most cases, “not a worry”.

Having multiple family members with the disease and younger than 50 could point to one of a collection of gene mutations that increased cancer risks, however, she said. These included BRCA1, BRCA2 and TP53 mutations. Such women could ask their GPs if a referral for risk assessment was warranted. “In Ireland we already have arrangements in place through the National Cancer Control Programme and the National Centre for Medical Genetics programme,” Dr O’Reilly said.

These services were available for public access upon referral, as were services in the Mater and St James's hospitals in Dublin and Cork University Hospital.

DNA test
In some cases where strong familial links with the disease were shown a DNA test could be warranted, she said.

These were carried out in the UK and would indicate whether a woman had any of the critical genetic mutations that raised her risk of cancer.

At that point risk could be lowered either by surgery or by regular magnetic resonance imaging (MRI) scanning, she said.

This type of screening meant cancer could be detected earlier, which improved survival. Surgery could reduce the risk to about 5 per cent, she added.

The Health Information and Quality Authority was asked by the NCCP to recommend a surveillance programme that could help women in the high-risk category. It published its report three weeks ago, which said scanning for high-risk women aged between 30 and 49 could reduce deaths and be “cost effective”.

Mater Private Cancer Genetics Clinic founder Dr David Gallagher said a private patient would pay between €500 and €1,400 for the genetic test.