Breast cancer is a medical term that strikes fear into the hearts of many women. While we used to believe that it struck randomly, researchers and scientists now know that there are specific risk factors for breast cancer. And, by knowing those risk factors we can reduce our own risk for developing this dreaded disease.
A risk factor is anything that affects the chances of getting a disease, such as cancer. Researchers have found that different illnesses and different cancers have very different risk factors. For instance, you have a higher risk of developing skin cancer if you spend hours of unprotected time in the sun. Smoking is a risk factor for cancers of the lung, mouth, bladder, kidney and several other organs.
However, having a risk factor does not necessarily mean you get the disease. It only means that you have a higher risk of getting the disease than other women who do not carry that same risk factor. And, researchers have found that women who don’t appear to carry any risk factor will also develop breast cancer as they grow older.
Some of these risk factors we can change and the others we have no control over. For instance, simply being a woman increases your chance of having breast cancer. Although men can also develop cancer of the breast, it is more likely to develop in women. The main reason that women develop breast cancer is that their breast cells are constantly exposed to female hormones that promote the growth of these cells.
Risk factors that are related to your lifestyle include not having children or having them after the age of 30. Becoming pregnant at a younger age reduces the risk of breast cancer and pregnancy reduces the woman’s total number of lifetime menstrual cycles which may be the reason for this effect. (1) Studies have determined that women who use oral contraceptives do not have a greater risk of breast cancer than women who have never used them. (2)
Another hormonal therapy which raises the risk of women who have breast cancer is postmenopausal hormone therapy also known as hormone replacement therapy. It was used for many years to relieve symptoms of menopause and to help prevent osteoporosis but today has been found to increase the risk of uterine cancer and breast cancer. (3)
Some new studies are also suggesting that breast-feeding can slightly lower the risk of breast cancer, especially if it continued for 1 1/2 to two years. The explanation for this effect may be that it reduces the woman’s total number of lifetime menstrual cycles.
The use of alcohol is clearly linked to an increased risk of developing breast cancer as is being obese, especially for women after menopause. Having more fat tissue after menopause can actually increase your chance of getting breast cancer because it raises your estrogen levels and most breast cancers are dependent upon estrogen. (1)
There is also a growing body of evidence that physical activity will help reduce breast cancer. In the Women’s Health Initiative researchers found that as little as 1 1/2 to 2 1/2 hours per week a brisk walking will reduce a woman’s risk by 18%. (4) The American Cancer Society recommends 45 to 60 minutes of intentional physical activity five or more days per week to help reduce the risk of cancers.
There are other factors which are controversial or unproven in the risk of developing breast cancer. These are high fat diets, the use of aluminum-based antiperspirants, a certain types of bras which constrict lymphatic drainage, induced abortions, breast implants, smoking, working at night and environmental chemicals.
There are also risk factors which we cannot control. The first of these is age. About one out of eight invasive types of breast cancer are found in women who are younger than 45 while two out of three are found in women who are older than 55. (3)
There are also genetic risk factors which we cannot change. Approximately 10% of women who develop breast cancer will have some hereditary gene that was inherited from their parents. The most common cause is a mutation of BRCA1 and BRCA2 genes. If you inherit a mutated copy of either one of these genes one of your parents you have a higher risk of developing breast cancer during your lifetime. This risk can be as high as 80%.
There are other gene mutations that can also lead to inherited risk but are not frequent cause of breast cancer. ATM, p53, CHEK2, PTEN ADH1 are mutations that can potentially increase risk. Genetic testing can be done, although it may be helpful in some situations many women have to weigh the pros and cons carefully.
A similar consideration to genetics is family history of breast cancer. Breast cancer is higher among women who have a close blood relative who also develop this disease. Women who have a personal history of breast cancer has a three to four greater chance of developing a new cancer in the other breast which is different from a recurrence, or return, of the first cancer.
African-American women are more likely to develop breast cancer as are women who have denser breast tissue or who have certain benign breast conditions. Breast conditions which increase risk are complex fibroadenomas, sclerosing adenosis, a radial scar or papillomas. (1)
While the excretion of estrogen protects women against cardiovascular disease it appears that those who have had more menstrual cycles because they started at an earlier age or went through menopause at a later age have a slightly higher risk of breast cancer. Any radiation to the chest area for another type of cancer, such as Hodgkin’s disease or non-Hodgkin’s lymphoma, also has a slightly increased risk for breast cancer.
References
(1) BreastCancer.org: Breast Cancer Risk Factors
http://www.breastcancer.org/risk/factors/
(2) The New England Journal of Medicine: Oral Contraceptives and Risk of Breast Cancer
http://www.nejm.org/doi/full/10.1056/NEJMoa013202
(3) American Cancer Society: What are the Risk Factors for Breast Cancer?
http://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-risk-factors
(4) National Cancer Institute: Physical Activity and Cancer
http://www.cancer.gov/cancertopics/factsheet/prevention/physicalactivity
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