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AT and breast cancer

It has been known for some time that both women with AT and women who carry the AT gene but don’t have AT themselves, for example the mothers of people with AT, have a greater than normal risk of developing breast cancer.

Incidence of breast cancer in women with AT

Breast cancer affects about 1 in 8 women in the general population (12%) most commonly after the menopause. Women with AT have a substantially higher risk of developing breast cancer from age 25 years. It has been estimated that nearly half all women with AT will develop breast cancer by the age of 50 years but this number is based on very small studies so we do not know how accurate it is. The level of risk may be different for women with milder forms of AT, but again we cannot be sure about this.

Incidence of breast cancer in carriers of the gene

Women who are carriers of the AT gene mutation have a moderately increased risk of breast cancer. Mothers of people with AT are always carriers, while other female family members such as sisters or aunts may be and can request testing, by asking their GP to refer to their local Clinical Genetics Service.

A study in the UK suggested that over their lifetime an ATM mutation carrier has a 1 in 6 chance (16.6%) of developing breast cancer compared to a 1 in 8 chance (12%) for the general population. However, the chance of developing breast cancer before the age of 50 for an ATM mutation carrier is about 1 in 11 (8.8%). This is over four times higher than the risk for the general population, which is 1 in 48 (2%).

It should be stressed that the figures above apply only to women. Men in the general population are at a very low risk of breast cancer anyway. To put this into perspective, almost 46,000 new cases of breast cancer are diagnosed in the UK each year, of which only 300 or so are in men.

Breast cancer screening

The NHS in England has screening guidelines for both groups of women. The guidance is as follows:

Women who have AT

It is recommended that women with AT should be offered annual MRI screening from the age of 25, or from the time of diagnosis should this be later. It is not recommended that mammography be carried out on women with AT for routine surveillance, although it may have a role in assessing an abnormality found on MRI. This screening should continue throughout their lives.

Women who carry the AT gene

Breast screening protocol for women who carry the AT gene has recently been under review and we will publish the new guidance as soon as possible.  In the meantime, please contact the AT Society support team if you have any questions about breast screening. Office phone number is: 01582 760733 or email: [email protected]

Information for health professionals: The CanRisk tool is currently being used to assess female carriers risk factors when their child is seen at the National Paediatric AT service in Nottingham. Outcomes of the assessment and any recommendations for local health professionals are then added to the child’s clinic report.  The CanRisk tool can be accessed here:


Accessing screening

Women with AT over the age of 25 in England are advised to go to their GPs and ask to be referred to the breast cancer screening programme. Because GPs and the screening service may will not have come across this issue before, it is advisable to take a copy of the protocols with you.

The situation for the other nations varies. While the guidelines don’t formally apply, the same advice for women in England applies to women in Northern Ireland. Women in Scotland should ask their GP to be referred to the regional genetics unit, where they will be assessed for appropriate screening. In Wales, only routine screening from the age of 50 is currently available. However, this is an issue that we will be taking up with the NHS in Wales.

Wherever you live, if you have any problems accessing the screening service or getting a GP referral, please contact us on 01582 760733 and we will do all we can to support you. It would also be very helpful to hear what experiences you have, positive or negative, in accessing the service.