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Can I take a blood test to find out my risk of breast cancer?

Dear Doctor There is a history of breast cancer in our family and I have heard about a genetic test. How does this work?

I have heard that there is a blood test to see if you are at risk of getting breast cancer. As there is a history of breast cancer in my family, should I be tested?

There is a genetic blood test available to check for specific genetic mutations (BRCA1 and BRCA2) linked with breast and /or ovarian cancer.

A woman's risk of developing breast and/or ovarian cancer is significantly increased if she inherits these mutations. But not every woman who has this genetic mutation will develop cancer. Cancer in families can also be due to other genetic or environmental factors.

It is best to test the family member who has the cancer; if that person is found to have the harmful BRCA1 or BRCA2 mutation, other members can be tested, too.

What if I have this test and it comes back positive?

A positive test result provides information on your risk of developing these cancers. It does not tell you if you will develop cancer, or when.

If the test is positive, there are several options available to help manage your risk. Genetic counselling is strongly advised before and after the test. It will help you make an informed decision, and understand the benefits and risks of the test.

When should I start to have mammograms?

A screening mammogram is used to detect cancer before any clinical signs are noticeable, when it may be most treatable. But a mammogram is not always accurate. It can miss one in five breast cancers. If your mammogram is abnormal, other tests such as breast ultrasound or breast biopsy may be needed.

In Ireland, screening mammograms are offered to women aged 50 to 64. In America, women are advised to begin having mammograms at 40. If you are high-risk then screening mammograms may need to begin before you are 40. But women under 40 tend to have more dense breast tissue and this can make it hard to detect changes. This can be overcome by combining a mammogram with a breast ultrasound.

Screening should include breast examination by a doctor as well as a mammogram and/or ultrasound.

Should I examine my breasts myself and how often should this be done?

What's stressed now is "breast awareness" -- being familiar with the normal consistency of your breasts. Many women find lumps or changes in their breasts, some of these are normal changes that occur at different times of the menstrual cycle. If you decide to self-examine your breast, it is best to do this within the week after the last day of your period, when your breasts are less tender. If you have no periods, choose the same day each month. The main message is that if you notice any change you should visit your doctor.

For more information see www.genetics.ie