How our genes and body traits affect breast cancer risk.
How do the genes we inherit from our parents and the characteristics of our bodies affect our risk of developing breast cancer?
For more information on any of the below factors, see our booklet Breast cancer risk: the facts.
The following factors can increase the risk of breast cancer developing
As you get older, your risk of breast cancer increases. At least four out of five of all breast cancer cases in the UK are in women over the age of 50. The disease is uncommon in women under the age of 40.
Women are much more likely to get breast cancer than men, so simply being a woman means you are at higher risk of developing the disease.
For women, being taller slightly increases the risk of developing breast cancer. Conversely, being shorter slightly decreases risk.
Women who started their periods at an early age have a slightly increased risk of breast cancer. The earlier you began your periods, the higher your risk, but this effect is small and gradual.
In a small number of cases, breast cancer runs in the family. Of all women who develop breast cancer, up to 15% has a significant family history of the disease and about one in 20 has inherited a fault in a gene linked to breast cancer. If you have concerns about any cancers in your family then you should see your doctor.
Watch our animation to find out how faulty breast cancer genes are inherited:
For information about UK services for people with a family history of breast cancer please see our family history guide.
High breast density
The amount of tissue compared to fat in your breasts is known as ‘breast density’. Having high breast density (a low proportion of fat) is one of the biggest risk factors for breast cancer. Unfortunately, most women will not know their breast density and there are no established ways to reduce it.
Women who go through the menopause later have a slightly increased risk of breast cancer. The later you go through menopause, the higher your risk, but this effect is small and gradual.
Other breast conditions (proliferative benign breast disease)
There are many types of benign (non-cancerous) breast conditions and most do not affect the risk of developing breast cancer. However, if you have a benign breast condition where the breast cells are described as ‘proliferative’ (meaning the cells are growing too quickly) then your risk of breast cancer will be increased.
Your ethnic background affects your risk of developing breast cancer. In England, a white woman is more likely to develop breast cancer than a black, Asian, Chinese or mixed-race woman.
For the following factors, there is some scientific evidence that suggests they may affect the chances of developing breast cancer. More research is needed before we can be sure whether or not they are definitely linked to the disease.
Bigger size at birth
It is possible that women who were longer or heavier when born have a slightly greater risk of developing breast cancer than women who were smaller or lighter at birth.
Results of studies looking at a possible link between miscarriage and breast cancer do not all agree. More research is needed before we can be sure whether or not miscarriage affects breast cancer risk, and how.
The following factors are unlikely to affect breast cancer risk
For these factors, the overall scientific evidence suggests they aren’t linked to the disease. In some cases there simply isn’t any evidence of a link; in others, research has shown there’s no link.
It is unlikely that having an induced abortion (a planned termination out of choice or medical necessity) affects your risk of developing breast cancer.
Information last reviewed: July 2015