There are many breast cancer risk factors, including some that carry more risk than others, some that are lifestyle related and some that are based on family history/genetics. The key breast factor risks include:
Exogenous hormones (oestrogen)
Previous breast disease
Lifestyle Factors (alcohol, obesity)
Age is the biggest risk factor in breast cancer (after gender) with older women being much more at risk than younger women. This is why NHS screening programmes start at the age of 50.
There are many factors related to reproductive history that affect the risk of breast cancer. Women in developed countries have a higher risk of breast cancer largely as a result of the late age of first pregnancy, having lower numbers of children and less breastfeeding. The age when a woman starts her periods, the age at menopause, the number of children she has and the age at first birth can all affect risk.
Hormone therapies such as HRT and some high-dose oestrogen-only oral contraceptives have been found to increase the risk of breast cancer. In both cases, the risk is temporary and will decline over a period of years after the treatment is stopped.
Breast density is strongly related to breast cancer risk and breast tissue that is denser presents a higher risk. Breast density does have a significant inherited component but can also be affected by weight, menopause and the number of children a woman has had.
Many non-malignant breast conditions can cause an increased risk of breast cancer but this is usually discovered after a breast biopsy.
If you have a mother or sister who has had breast cancer your risk factor is higher than that of a woman with no family history. The risk increases further if your relative was diagnosed with breast cancer under the age of 40.
If there are more than four female 1st or 2nd degree relatives within a family that have had breast cancer, there may be a genetic mutation of the BRCA1 or BRCA2 genes and women with this mutation have a 50-80% chance of developing breast cancer before the age of 70.
There are many lifestyle factors that are found to increase the risk of getting breast cancer. They include:
Weight – being overweight or obese may increase the risk in post-menopausal women.
Physical activity – being physically active and remaining so may reduce your risk.
Alcohol consumption – increased alcohol consumption does increase your risk.
Shift work – shift work including night shift work has been found to increase the risk of breast cancer due to alterations in biological rhythms from disrupted and shortened sleep.
Radiation exposure – exposure to ionising radiation can increase the risk of breast cancer and the risk is higher if the exposure occurred at a younger age.