Risk factors that can’t be changed
Breast cancer is the most common cancer facing Australian women and while there are some choices you can make to reduce your chance of developing breast cancer, there are other risk factors that you have no influence over. Researchers are working out ways to understand which women have a higher risk, via tools such as genetic testing, to the impact of having dense breast tissue on detection and preventing breast cancer. It’s important to remember that these are risk factors only and that none of these definitely mean you will develop breast cancer.
Being a woman
99 per cent of breast cancer cases are women. A small minority of men can get breast cancer, but women are at a much higher risk.
The older women get the higher their risk of developing breast cancer. In Australia, breast cancer can occur in younger women, but about three out of four breast cancer cases occur in women aged 50 years and older.
Reaching puberty early prolongs the amount of time you are exposed to the fluctuating levels of estrogen and other female hormones that are associated with the menstrual cycle. Starting menstruation before the age of 12 is associated with higher breast cancer risk.
Women who experience menopause later (at age 55 or after) have twice the risk of developing breast cancer of women who experience natural menopause at ages younger than 45.
Breast cancer is a common disease so having one relative diagnosed over the age of 40 is not unusual and would not normally suggest that other family members are at increased risk. However, you might have an increased risk of developing the disease if several blood relatives in your family have had breast cancer or ovarian cancer and may be unknowingly passing a faulty gene down the family line.
BRCA1 and BRCA2
Women who carry a fault in the BRCA1 or BRCA2 genes have a high lifetime risk of breast cancer, estimated to be in the range of 30-60 per cent, and a lifetime ovarian cancer risk of about 20 per cent. Genetic testing is available for high risk women who are referred by their doctor.
Studies have found that being 175cm or taller is associated with a slightly increased risk for breast cancer.
High breast density
Women with dense breast tissue are more likely to be diagnosed with breast cancer than women with less dense breasts. Breast density is measured by mammograms however dense breast tissue and tumours show up as white and bright on a mammogram so a potential tumour could go undiagnosed.
Women from different ethnic backgrounds have varying rates of risk for breast cancer. Caucasian and Jewish women are among the highest; Asian women among the lowest rates for breast cancer.
Previous breast cancer
Being previously diagnosed with a non-invasive breast condition such as ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS), is associated with an increased risk of developing invasive breast cancer. In around 30 per cent of all breast cancer cases, the cancer will return later in life. This metastatic stage of breast cancer is not currently curable.