It has been known for some time that both women with A-T and women who carry the A-T gene but don’t have A-T themselves, for example the mothers of people with A-T, have a greater than normal risk of developing breast cancer.
Incidence of breast cancer in women with A-T
Breast cancer affects about 1 in 8 women in the general population (12%) most commonly after the menopause. Women with A-T have a substantially higher risk of developing breast cancer from age 25 years. It has been estimated that nearly half all women with A-T 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 A-T, but again we cannot be sure about this.
Incidence of breast cancer in carriers of the gene
Women who are carriers of the A-T gene mutation have a moderately increased risk of breast cancer. Mothers of people with A-T 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 A-T
It is recommended that women with A-T 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 A-T 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 A-T gene
It is recommended that women carrying the A-T gene who are between the ages of 40 and 50 should be offered a mammogram every eighteen months. From the age of 50 they should join the normal screening programme, which begins at the age of 50 and from then on will be screened every three years.
All screenings should be performed using the lowest dose of radiation and two-view digital mammography. Where possible this should be carried out using a full field direct digital mammography machine (FFDM), which should ensure that the lowest possible doses of radiation are used to achieve the required quality of mammogram.
Women over the age of 70 are encouraged to continue with breast screening but will need to request an appointment through their GP or local screening unit, as they will no longer be automatically invited for mammographic screening.
This guidance was formally published in March 2013. General guidance on breast screening for women with a higher risk is available on the Breast Cancer Screening Service website and in particular in the Surveillance protocols for women at higher risk of developing breast cancer. The guidance is set out clearly on page 6.
Women carriers between the ages of 40 and 50 and women with A-T 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.