Women are most likely to develop breast cancer; every year around 41,000 new cases of breast cancer are diagnosed in women (men can also suffer from breast cancer, and although it is rare, approximately 300 men are diagnosed each year).
Age is the single most important factor in influencing breast cancer risk – the older a woman is the higher her risk of developing breast cancer. 80 per cent of all breast cancers occur in post-menopausal women (based on the average age of menopause being 50).
Women who have previously had breast cancer face an increased risk in developing the disease again.
Women with a hereditary genetic susceptibility account for between five to 10 per cent of all breast cancer cases. They tend to have a strong family history of breast or ovarian cancer and these cancers usually occur in close family members, such as their grandmother, mother, aunt or sister, at an early age.
Hormones play an important role in the development of breast cancer:
- Not having children – The risk of having breast cancer is reduced by having children at a younger age–the more children a woman has, the lower the risk.
- A late first pregnancy – A woman who has her first child in her thirties is 63 per cent more likely to develop breast cancer before menopause and 35 per cent more likely to develop the disease afterwards than a woman who has her first child at 22.
- Breastfeeding – Breastfeeding helps protect against the disease. The longer a woman breastfeeds her children, the more she lowers her risk.
Hormone Replacement Therapy (HRT) causes a small increase in risk. But the risk gradually returns to normal after the woman stops taking hormones.
Overweight – Being overweight after menopause increases the risk of breast cancer.
Hereditary – A small number of women are at especially high risk because of faulty genes they have inherited. However, faults in known high-risk breast cancer genes such as BRCA1 and BRCA2 account for fewer than 1 in 20 breast cancer cases.
Alcohol – Regularly drinking large amounts of alcohol slightly increases the risk of breast cancer.
Mammographically dense breasts, or the pattern of a woman’s breast tissue on a mammogram, is associated with an increased risk of disease (the more dense the mammogram, the higher the risk of breast cancer).
Benign breast disease – Certain types of benign breast lumps increase risk of breast cancer. Benign breast disease can be classified as nonproliferative breast disease, proliferative breast disease without atypia, and proliferative breast disease with atypia. The latter two conditions increase risk of breast cancer.
Radiation – Long-term exposure to radiation, or moderate to high levels of exposure, increases the risk of breast cancer.