Breast Cancer Risk Factors

There is no single cause of breast cancer – it results from a combination of our genes, the way we live our lives and our surrounding environment.

Many things that affect your risk of breast cancer cannot be changed, such as your age. However, there are changes you can make to your lifestyle to reduce your risk of breast cancer.

Having particular risk factors doesn’t mean that you will definitely get breast cancer and conversely, not having many risk factors doesn’t mean that you won’t.

Risk factors simply increase or decrease your chances of developing the disease. So, even if you have a risk factor and are diagnosed with breast cancer, there’s no way of proving that the risk factor actually caused it.

Some factors increase your risk, while others decrease it or have differing effects in different women or at different times of their life:

Established factors

Age, alcohol, being female, being taller, early puberty, genetics - breast cancer in the family, high breast density, hormone replacement therapy (HRT) ionising radiation, late menopause, other breast conditions – proliferative benign breast disease, the pill

Possible factors

Bigger size at birth, in vitro fertilisation treatment, shiftwork – working at night, smoking, stress

Established factors

Being shorter, breastfeeding, early menopause, late puberty, physical activity

Possible factors

Aspirin and ibuprofen, healthy diet, smaller size at birth

Established factors

Ethnicity, pregnancy, weight and weight gain

Possible factors

Miscarriage

Doubtful factors:

Abortion, breast implants, bumping or bruising the breast, chemicals in the environment, deodorants, antiperspirants and shaving, non-ionising radiation, underwired bras

There are some positive changes you can make to reduce your risk of developing breast cancer. To find out more, take our quiz.

For questions and answers on risk and other topics, see our FAQs section.

Information last reviewed: 1 November 2011