Some breast cancer risks you don’t have any control over and you can’t change them. Women should take note of all risk types, however, in order to increase awareness of symptoms.
The risks for breast cancer can be divided into two types – risks you can change and those you can’t. The ones listed below you don’t have any control over and you can’t change them. However, you should take note of both types so that you know what you’re up against.
Breast cancer is about 100 times more common among women than men. The main reason women are more likely to develop breast cancer is because their breast cells are constantly exposed to the growth-promoting effects of the female hormones oestrogen and progesterone.
Family history of breast cancer
The strongest association with an increased risk for breast cancer is a family history, specifically breast cancer in first-degree relatives (mother, sister, daughter), which approximately doubles a woman’s risk. Having two first-degree relatives with breast cancer increases a woman’s risk about five-fold.
About 20 to 30% of women with breast cancer have a family member with this disease. (It’s important to note this means that 70 to 80% of women who get breast cancer do not have a family history of this disease.)
Your risk of developing breast cancer increases as you get older. About 1 out of 8 invasive breast cancers are found in women younger than 45, while about 2 out of 3 invasive breast cancers are found in women aged 55 or older.
Genetic risk factors
Mutations of the BRCA1 and BRCA2 genes are the most common hereditary causes of breast cancer in women. In some families with BRCA1 mutations, the lifetime risk of breast cancer is as high as 80%, but on average this risk seems to be in the range of 55% to 65%. For BRCA2 mutations the risk is lower, around 45%.
Other much less common gene mutations can also lead to inherited breast cancers. In total, about 5% to 10% of breast cancer cases are thought to be hereditary, resulting directly from gene changes (called mutations) inherited from a parent.
Personal history of breast cancer
A woman with cancer in one breast has a three- to four-fold increased risk of developing a new cancer in the other breast or in another part of the same breast. This is different from a recurrence (return) of the first cancer.
Race or ethnicity
White women are slightly more likely to develop breast cancer. African, Asian and Hispanic women have a lower risk of developing and dying from breast cancer.
Dense breast tissue
Women with denser breast tissue (as seen on a mammogram) have more glandular tissue and less fatty tissue, and have a higher risk of breast cancer.
Certain benign breast conditions
Women diagnosed with certain benign breast conditions may have an increased risk of breast cancer.
Women who have had more menstrual cycles because they started menstruating at an early age (before age 12) and/or went through menopause at a later age (after age 55) have a slightly higher risk of breast cancer.
Previous chest radiation
Women who, as children or young adults, had radiation therapy to the chest area as treatment for another cancer (such as Hodgkin disease or non-Hodgkin lymphoma) are at significantly increased risk for breast cancer.
From the 1940s through the 1960s some pregnant women were given the drug diethylstilbestrol (DES) because it was thought to lower their chances of losing a baby (miscarriage). The daughters of these women have a slightly increased risk of developing breast cancer after the age of 40.
Diethylstilbestrol and cancer. Retrieved from http://www.cancer.gov/about-cancer/causes-prevention/risk/hormones/des-fact-sheet.
What are the risk factors for breast cancer? Retrieved from http://www.cancer.org/cancer/breastcancer/detailedguide/breast-cancer-risk-factors.
Women who receive chest radiation therapy to treat childhood cancer have higher risk of breast cancer. Retrieved from http://www.breastcancer.org/research-news/childhood-radiation-increases-risk.
(Revised by M van Deventer)