Between 5 and 10% of all breast cancers are thought to be hereditary. This means that most breast cancers (9 out of 10) happen sporadically or spontaneously, ie without a family history. Breast cancer is a common cancer – about 1 in 10 women in the UK will get it during their lifetime (around 10%). So if you have just one or even two elderly relatives diagnosed with breast cancer, it does not mean that you are at much increased risk yourself.

However, if you have any of the following in your close family you might want to see your GP and be referred to a familial cancer clinic:

• three close blood relatives (from the same side of the family) who developed breast cancer at any age, or
• two close relatives (from the same side of the family) who developed breast cancer under 60, or
• one close relative who developed breast cancer aged 40 or younger, or
• a case of male breast cancer, or
• a case of bilateral breast cancer (this means in both breasts).

Breast cancer is very rare in men, but men can pass on a breast cancer gene to their children. So it is possible to inherit a breast cancer gene from your father's side of the family.

As some of the known cancer genetic mutations cause an increased risk of both breast and ovarian cancer, they may play a role if you have members with ovarian cancer and breast cancer in your family. So you should be referred to a specialist if you have:

• a minimum of one of each tumour (ie one breast cancer, one ovarian cancer), with the breast cancer being diagnosed under 50 years. This can also be in the same person. or
• two cases of ovarian cancer in your close family.

If you are thought to be at significantly higher risk of breast cancer than the general population you will be offered breast screening (mammograms) from the age of 40. At 50, all women in the UK, regardless of their personal risk, are offered regular breast screening. Mammograms (breast x-rays) cannot prevent breast cancer, but they can help to detect it at an earlier stage, which increases the chances of successful treatment. There is a theoretical risk that the x-ray radiation from the mammogram can cause cancer. However, the amount of radiation from a mammogram is tiny and doctors believe that this theoretical risk is outweighed by the benefit of detecting breast cancer earlier. We have further information about breast cancer and mammograms.

Unfortunately, there is currently little reliable evidence to show that breast screening can make a big difference for the successful treatment of high-risk women under 50. The UK's National Institute for Health and Clinical Excellence (NICE) is an independent body that gives guidance to doctors on prevention and treatment of ill health. NICE's Familial Breast Cancer Guideline recommends that women are offered yearly mammograms, if they are aged between 40 and 49 and have an increased risk of developing breast cancer because of their family history. This advice may change in the future when the results of a study known as the FH01 Study are known. The FH01 Study is looking at how effective mammographic screening is for women between the ages of 40 and 50.  The study will show whether breast screening for women under 50 who have a significant family history of cancer can improve their chances of being successfully treated.

In the UK, screening is not usually offered to women under 40 because:

• mammograms don't work as well for very young women, as their breast tissue is denser than that of older women
• of the theoretical risk that radiation doses from having many screening tests could cause cancer.

Other scans, such as magnetic resonance imaging (MRI) and ultrasound scans, can pick up changes in the breasts, but these are not routinely used. MRI scans may be recommended for some women under 50, who are at higher than average risk of developing breast cancer; depending on their family history and level of risk. For women over 50, MRI scans will not be routinely available for breast cancer screening. You might be very worried about your breast cancer risk but find that you are not eligible for regular breast screening before the age of 50. Some women in this situation consider paying for regular screening tests from private healthcare companies. If you are under 35, or you don't have a very strong family history, regular mammograms in the private sector may not be the right option for you, even if you are very worried. In this situation it is best to speak to a breast care nurse or to your genetic counsellor about why you are worried and what you could do to help yourself feel better.

It is important to remember that there is currently no good evidence to show that yearly mammograms are definitely helpful to women under 50 who have a strong family history. You can read more about this topic in our section on breast screening in women under 50. However, as a general rule, earlier detection of breast cancer makes it easier to treat and more likely to be cured. It is important for you to discuss the pros and cons of breast screening with your genetic counsellor or GP before you decide to pay for private mammograms. You can then ask them for the contact details of private mammogram services if you decide that this is what you want to do.

Some women with a higher than normal risk of ovarian cancer are offered screening for ovarian cancer. There is not yet enough firm evidence on whether ovarian screening is effective in detecting early ovarian cancer. Therefore, the screening will usually be part of a research trial. A big national research study United Kingdom Familial Ovarian Cancer Screening Study (UKFOCSS) is being carried out to try to develop effective screening for ovarian cancer for women with a family history of ovarian cancer. To be eligible for this study you need to have ovarian, not just breast, cancer in your family (unless a cancer susceptibility gene has been identified in your family). Being part of the study will involve regular blood tests and ultrasounds (a painless test using sound waves to build up a picture of your ovaries). Research so far suggests that this screening gives a number of false positives. This means that a test result shows abnormalities without there actually being anything wrong with your ovaries. In this case, further tests will have to be done to clarify the results. These further tests (such as surgery) can carry risks. This means that you might be exposed to these risks even though there is nothing wrong with your ovaries.

If you are eligible for the UKFOCSS trial, because you have a strong family history of ovarian cancer, you need to make a decision about whether you want to take part in this research. We have further information about ovarian cancer and about taking part in research trials, which might help you make this decision.

If the doctor or nurse thinks you are at high risk of breast or ovarian cancer, they might offer you genetic testing, which you do not have to accept. You will not normally be offered genetic testing if you have only one close relative with breast cancer.

Two genes that are involved in familial breast and ovarian cancer have been identified: BRCA 1 and BRCA 2 (short for breast cancer 1 and 2 genes). In some families who have a very strong history of breast cancer and are tested, no mutation in the BRCA1 or 2 genes is found. This makes it very likely that there are other genes involved in breast cancer, but that they haven't been identified yet.

Testing for BRCA 1 and 2 mutations is a two-step process. First the BRCA 1 or 2 mutation has to be found in a relative who has been diagnosed with breast or ovarian cancer. In the NHS this mutation search can take up to 12 months. Only if a mutation is found (and this is often not the case), can predictive testing be offered to other family members.

There is a slightly faster service available to people of Ashkenazi (Eastern European) Jewish, Polish or Icelandic origin. Some common mutations (founder mutations) have been identified in these communities. Faster genetic screening for founder mutations in these communities can be offered by the NHS. As the details of these mutations are known (i.e. where to look in the gene), it is not necessary to find the specific family mutation in a relative who has been diagnosed with cancer first. So if you have Ashkenazi Jewish, Polish or Icelandic ancestry, you might be able to have predictive testing, without going through mutation searching first.

Most people of Jewish descent in the UK are of Ashkenazi (Eastern European) origin. It is therefore helpful to tell your doctor if you have Jewish ancestry and you are worried about your family history of breast or ovarian cancer.

For some women, their family history suggests a high genetic risk but predictive testing cannot be offered because the initial mutation cannot be found. Some women decide not to have a gene test. In situations like this all female blood relatives over 40, whether they might actually carry the genetic alteration or not, will usually be offered regular breast screening.

BRCA gene mutation screening is also available privately. You will have to pay for these tests.

You can find information about genetic testing clinics on the UK Genetics Testing Network website at: www.ukgtn.org