Is Breast Cancer Hereditary in Women?

Breast cancer is the most common type of cancer in women. Although we don’t yet know enough to be able to predict who will be affected by cancer, we do know that it can sometimes run in families. We have also identified some genes that can put you at risk of breast cancer. However, that doesn’t mean that all cases of breast cancer are hereditary. In fact, only about 5-10% of breast cancers are likely to be caused by hereditary factors.

---

Family History of Breast Cancer

The family history is important, particularly breast and ovarian cancer in women and prostate cancer in men. If you have a close relative (such as a mother or sister) who had breast or ovarian cancer or a male relative had prostate cancer, then you might be more likely to develop breast or ovarian cancer, especially if they were affected at a young age.

However, it is important to remember that cancer is very common and that breast cancer is particularly common in women. It is possible for more than one person in the family to be affected by cancer simply by chance, even if they aren’t carrying a gene that puts them at higher risk. Even if someone in your family has had breast cancer, it doesn’t mean that you will develop it too.

Genetics and Breast Cancer

The chances of developing breast cancer can depend on many different factors, including your age and lifestyle as well as your genes. It is likely that there are many different genes that can affect your chances of developing breast cancer. Some may help to protect you, while others could increase the risk. If there is a history of breast or ovarian cancer in your family, then it could be due to some of these higher risk genes.

The two most influential and best understood genes for breast cancer are BRCA1 and BRCA2. Women who carry these genes are at higher risk of developing breast and ovarian cancer. If you have a faulty copy of one of these genes there is up to a 7 in 10 chance that you will be affected by breast cancer by the time you are 80.

If someone in your family has been tested and found to carry the BRCA1 or BRCA2 genes then there is a chance you may be carrying them too. However, there is only a 1 in 2 chance of the gene being passed on from parent to child. If your mother has one of these genes then there is a 50% chance that you have it too.

What Should You Do If You’re at Risk of Breast Cancer?

If you have a family history of breast cancer then it is a good idea to talk to a doctor or genetic counsellor, especially if a relative has tested positive for BRCA1 or BRCA2. You will get personalised advice on your risk and whether you should be tested for these genes. You can also learn more about preventative treatments that could help to reduce the risks if you do have these genes.