The UK Study of MRI Breast Screening for Cancer
This study, supported by the MRC and NHS, is investigating whether magnetic resonance imaging (MRI) is an effective way of screening young women with a high risk of breast cancer. 839 women aged between 35 and 49 known to be at high risk have volunteered for the study. Recruitment is now closed. Each woman receives annual MRI measurements as well as conventional X-ray mammograms, until March 2004, to allow this new technique to be compared with current methods. At the end of the study women will revert to their normal screening regime - usually annual mammograms arranged through the genetics clinic.
The aim of the study is to decide whether MRI is a good method of detecting breast cancer in younger women with no symptoms. If proven to be of value it will give these high risk women an alternative option to drug prevention or surgery.
What is genetic predisposition to breast cancer and how common is it?
Every cell in our body contains two copies of all our genes, and these control how we develop (e.g. the colour of our eyes). When a cell changes into a cancer cell, several changes have occurred in both copies of these genes which result in unchecked growth of the cell. In most people who develop cancer, these genetic changes only occur in the cancer cell itself, however, in rare instances a change in one copy of the gene is inherited. These individuals have an increased risk of cancer development, and as half of all genes from each individual are passed to their children, there is a risk (50:50) of passing on the abnormal gene which carries an increased cancer risk. More than one genetic change is necessary to form a cancer cell and so the presence of a cancer-predisposition gene does not mean that cancer will develop , but the cancer risk is increased. About 5-10% of breast cancer cases arise in individuals who have inherited a breast cancer predisposition gene.
Who is likely to carry a breast cancer predisposition gene?
Women who have a family history of breast and/or ovarian cancer have a higher chance of carrying a breast cancer gene. The risk rises as the number of cases in the family increases, if the breast cancer occurred at a young age (less than 50 years) or if women have had breast cancer in both breasts.
What measures are available to high risk women at present?
The following measures are available to detect breast cancer early or prevent its occurrence.
breast awareness: this can be discussed with your GP or practice nurse
mammographic screening (usually from the age of 35 years in higher risk families)
Tamoxifen prevention (this is currently being offered within a UK trial); there is still much debate over this issue
prophylactic mastectomy i.e. a healthy woman has both her breasts removed. This would only be considered after full counselling.
How does screening work?
Screening cannot prevent breast cancer. It can, however, detect its presence before any lump can be felt within the breast. Many studies have shown that by detecting breast cancer early in this way, the treatment of the cancer is more successful and survival is improved.
The NHS Breast Screening Programme offers conventional X-ray mammography to women over 50. This is because women in this age group are likely to be past their menopause, which has the effect of reducing the density of the breasts. This means that the X-rays taken of the breasts are clearer and more likely to detect any cancer which may exist.
Why MRI?
In women at high risk, breast cancer more frequently occurs at a younger age. X-ray mammography is less helpful in women below 50 as the breast tissues are denser, making it harder to see disease on the X-ray films. Recent developments in new imaging techniques, using magnetic resonance imaging (MRI), provide a sensitive means of detecting disease in the breast. MRI scanners work by stimulating atoms in the body with a magnetic field and analysing the tiny radio waves they produce to make an image. The method allows us to obtain detailed 3D images of the breast made up of many planes or "slices", whereas X-rays provide only a single view looking through the breast. In addition a contrast agent that affects the magnetic properties of tissues is used. This is taken up in abnormal tissues. By studying the pattern of uptake, the measurement provides high sensitivity in detecting disease.
If MRI proves to be an effective method of screening young, high risk women it may provide an alternative to prophylactic mastectomy.
What do I do if I am concerned about my family history of breast cancer?
Most women with a family history will still not be at greatly increased risk of developing the disease. Those with 4 or more relatives with breast or ovarian cancer occurring younger than 60 are at most risk. If you are worried about your family history, you can discuss your concerns in the Cancer Family Clinic or Medical Genetics Clinic in your area by asking your GP to refer you.
The study
This screening study is looking only at women in the very highest risk groups although the results may also be of benefit to all women at increased risk. Recruitment to the study has now finished, but the eligibility criteria for participating women are:
Aged 35 to 49 and:
have already been genetically tested and been found to be carrying one of the breast cancer genes (BRCA1, BRCA2), or
4 or more relatives on the same side of the family who have developed breast cancer below the age of 60, or
4 or more relatives who have developed breast or ovarian cancer where the ovarian cancer is at any age, or
4 or more relatives affected by breast cancer, including any male breast cancer at any age.
Or, aged 25 to 49 and:
have already been genetically tested and been found to be carrying the p53 gene, or
a strong family history for Li Fraumeni Syndrome (LFS).
If you are worried about being at increased risk of breast cancer, please discuss your concerns with your GP, or you can contact the Hereditary Breast Cancer Helpline on 01629 813000.
For further information about the study, please contact the Co-ordinating Team on 020 8661 3720 or visithttp://www.icr.ac.uk/cmagres/maribs/maribs.html