This information is about breast screening in women below the age of 50. It covers mammography (the main method used for breast screening) and MRI scanning, and why they might be offered to women under 50.

It should ideally be read with our general information about breast screening. You might find it helpful to discuss things with the staff at your family history clinic.

Breast screening is a way of finding breast cancers early, when they are too small for you or your doctor to see or feel. In the UK, around 1 in 9 women will develop breast cancer at some time in their life.

Women with a significant family history of the disease may carry a higher risk of developing breast cancer, but it is important to recognise that:

• Most women do not develop breast cancer. Of those who do, most will not have a known family history of the disease.
• For most women, increasing age is the greatest risk factor for developing breast cancer.
• The majority of women with a family history of breast cancer do not fall into a high-risk category and do not develop breast cancer.
• The majority of women with a relative with breast cancer are not at a substantially increased risk of developing breast cancer themselves.

Each year, around one and a half million women in the UK have breast screening as part of the NHS Breast Screening Programme (NHSBSP). The NHSBSP is nationally coordinated and sets national standards.

A mammogram is a low-dose x-ray of the breast tissue. It tests for early breast cancer. You will need to remove your clothes from the top part of your body, including your bra. The radiographer will then position you so that each breast is placed, in turn, on the x-ray machine and gently but firmly compressed (squashed) against a flat, clear, plastic plate.

The breast tissue needs to be compressed to keep the breast still in order to get the clearest picture, using the lowest amount of radiation possible. Some women find the examination uncomfortable for a few seconds, while the breast is being compressed. Only a very few find this painful. You will need to stay still for less than a minute while the picture is being taken. The radiographer takes two pictures of each breast, in two different positions, to make sure they examine all the breast tissue.

Under the present Department of Health guidelines, all women registered with a GP and aged between 50 and 70, are offered a free mammogram every three years. If you are 70 or over, you are not automatically invited for breast screening. You can, however, make your own appointments for free mammograms every three years if you wish.

MRI scans use magnetism instead of x‑rays to build up a detailed picture of the breasts. During the scan you will be asked to lie very still on a couch inside a long tube for about 30 minutes. It is painless, but can be uncomfortable, and some women feel a bit claustrophobic during the scan. It is also noisy, but you will be given earplugs or headphones.

Some women are given an injection of dye into a vein in the arm, but this usually does not cause any discomfort.

MRI scanning is not generally used in breast screening on the NHS.

Breast cancer is not common in women under 50 and large research trials have shown that regular screening of this group doesn't help save lives. Other trials have shown that for most women under 50, the additional radiation exposure from regular mammography is more of a risk.

We also know that mammograms are less effective at detecting breast cancer in women who have not had the menopause (pre-menopausal women). The menopause happens, on average, around the age of 50. After the menopause, the glandular tissue in the breast decreases, which makes x-rays of the breast easier to read and so the results are more reliable.

This is why the effectiveness of breast screening is uncertain for women under the age of 50, and why it isn't routinely offered.

To help you decide whether or not to go for screening, the main benefits and difficulties are described below:

Benefits

• Breast screening may find cancers early.
• Breast screening in women over 50 saves lives.
• With breast screening, any cancer is more likely to be found early. If a cancer is found, it is likely to be smaller. It may, therefore, be possible to remove the lump (by a lumpectomy) rather than remove the whole breast (a mastectomy).

Disadvantages

• Mammograms can be uncomfortable.
• Mammograms involve x-rays. They only use a low amount of radiation. The radiation dose given by breast screening x-rays is continually monitored to make sure that it remains as low as possible, while still providing a good-quality image. However, if you start screening at a younger age, over your lifetime you will be exposed to more radiation. There is a very small risk that this could affect your health.
• Abnormal mammogram results may cause unnecessary worry. Around 1 in 20 women who go for screening will be called back for further investigations. Most women who have further tests will turn out not to have cancer. However, women who are called back often find this a very worrying time.
• Mammograms sometimes need to be repeated (for example, if the films are not very clear).
• Breast screening will not pick up all breast cancers. It is more likely that cancers will be missed in women who are pre-menopausal (under 50).
• Cancer may still occur in women having regular breast screening.

It is important to understand that breast screening cannot prevent cancer. You can read more about the pros and cons of mammography further on in this section.

The definition of whether a woman has a significant family history of breast cancer is quite complicated.

A member of the breast care team will talk to you about your family history. Then, possibly using questionnaires or computer programmes, they estimate your risk of developing breast cancer. This is a 'risk assessment'. If your risk level is similar to that of the general population, you can begin mammography when you reach 50. However, if your family history changes, you can contact the team for reassessment.

The National Institute for Health and Clinical Excellence (NICE) is an independent body that gives guidance to doctors on the prevention and treatment of ill health. NICE has produced guidance on the screening of women with an increased risk of developing breast cancer because of their family history. The guidelines currently classify women who have a higher chance of developing breast cancer, because of their family history, into two groups:

• moderate risk
• high risk

The type of care that will be recommended for you depends on your level of risk.

Moderate risk

If it is estimated that you are at moderate risk of developing breast cancer, you will generally receive care from the breast care team. You should be offered support and information appropriate to your individual needs and, depending on your age, you may also be offered mammography. If you are under the age of 50, you will be offered yearly mammograms from the age of 40. Women under 40 should only be offered regular mammograms as part of a research study.

According to the NICE guidelines, examples of women likely to be at moderate risk include women with one of the following in their family history:

• One first-degree relative diagnosed with breast cancer before the age of 40. (Your first-degree relatives are your mother, father, daughter, son, sister, brother.)
• Two first-degree or second-degree relatives diagnosed with breast cancer at an average age of over 50 years old. (Your second-degree relatives are your grandparents, grandchildren, aunt, uncle, niece, nephew, half sister and half brother.)
• Three first-degree or second-degree relatives diagnosed with breast cancer at an average age of over 60 years old.

(Note: these are only some examples taken from the NICE Guidelines so this is not an exhaustive list).

Where more than one relative is mentioned above, all relatives must be on the same side of the family, and must be blood relatives, of the person being assessed (and of each other).

High risk

Women thought to be at high risk of developing breast cancer will be offered referral to a specialist genetics service. Here, a specialist will carry out a more detailed assessment, to investigate the possibility of a genetic link in the family.

Less than one in 100 women are at high risk of developing breast cancer because of their family history.

According to the NICE Guidelines, examples of women who are likely to be at high risk include women with one of the following in their family history:

• two first-degree or second-degree relatives diagnosed with breast cancer before an average age of 50 – at least one must be a first-degree relative. (Your first-degree relatives are your mother, father, daughter, son, sister, brother. Second-degree relatives include grandparents, grandchildren, aunts, uncles, nieces, nephews, half sisters and half brothers)
• three first-degree or second-degree relatives diagnosed with breast cancer before an average age of 60 (one must be a first-degree relative)
• four relatives diagnosed with breast cancer at any age (one must be a first- degree relative)
• one first-degree relative with cancer in both breasts where the first cancer was diagnosed before the age of 50
• one first-degree or one second-degree relative diagnosed with ovarian cancer at any age and one first or second-degree relative diagnosed with breast cancer before the age of 50
• two first or second-degree relatives diagnosed with ovarian cancer at any age

(Note: these are only some examples taken from the NICE Guidelines so this is not an exhaustive list).

In the above examples, where more than one relative is mentioned, all relatives must be on the same side of the family, and must be blood relatives of the person being assessed (and of each other).

There are other factors that may influence your risk of familial breast cancer. For example, if you:

• have a close relative who has had breast cancer diagnosed in both breasts
• have a male relative with breast cancer
• have relatives with breast and ovarian cancer on the same side of the family
• have Jewish ancestry
• have a history of any rare, or childhood, cancers on the same side of the family.

You will be asked about such factors in your family during your consultation. It is also important to let your breast care team know if there are any changes in your family history as time goes on, as this may change your risk assessment.

For women under 50, who have an increased risk of developing breast cancer because of their family history, the current view of experts in the UK is that the benefits of screening are likely to outweigh any potential disadvantages.

Therefore you may be offered a yearly mammogram and sometimes an MRI scan before reaching 50, because your family history places you at a significantly greater risk level than that of the general population. Some women may be offered a combination of mammograms and MRI scans.

The NICE Familial Breast Cancer Guideline recommends that women with a moderate or high risk of breast cancer should be offered yearly mammograms between the ages of 40 and 49. Women aged 30 to 39 should only be offered a mammogram as part of a research study or when they can be closely monitored. Women aged between 20 and 49 may be offered an annual MRI scan if they have a high risk of developing breast cancer. This includes women who are known to have one of the faulty breast cancer genes.

Most women over 50 are usually offered a mammogram every three years as part of the National Breast Screening Programme. This is because breast cancer is easier to find in women over 50 and breast cancers are usually slower-growing in this age group. For women over 50, MRI scans will not be routinely widely available for breast cancer screening.

This screening advice may change in future, when the results of the study described below are known.

An NHS-funded research study is looking into whether or not there is actually a benefit in screening women who are at moderate or greater risk (because of their family history), aged 40-49 years. This study is called the FH01 Study, or Evaluation of Mammographic Surveillance Services in Women under 50 with a Family History of Breast Cancer. If you are aged between 40 and 44, and have a family history of breast cancer, you may be asked to take part in the study.

Other scans, such as ultrasound scans, can pick up changes in the breasts, but are not used routinely. They are sometimes used in individual cases (where a woman is at high risk of developing breast cancer) if a doctor feels they might be of help.

It is difficult to face any uncertainty about health. Making decisions about screening can be tough, and you may experience a range of powerful emotions, including anxiety and fear. Your breast care team will be able to support you, and in some centres specialist counsellors are available. Our nurses can also give you details of helpful organisations, throughout the UK.

This information has been compiled using information from a number of reliable sources, including:

• FH01 Study ‘Information for Patients’
• Familial Breast Cancer: the classification and care of women at risk of familial breast cancer in primary, secondary and tertiary care (partial update of CG14). National Institute for Health and Clinical Excellence (NICE). October 2006.