Mei Firestone, MD, is board certified in medical oncology, hematology and internal medicine. She treats all types of cancers and malignant blood disorders, with a focus on breast and gynecological malignancies. Dr. Firestone practices with LMG Cancer & Infusion Center.
Breast cancer is the most common cancer diagnosed in women: 1 in 8 women will get it in their lifetime. Experts predict that in 2017, more than 250,000 women in the U.S. will be diagnosed with breast cancer, and more than 40,000 of them will die from the disease.
Fortunately, women can take steps to reduce their risk.
What Factors Increase Breast Cancer Risk?
There are many factors that can affect a woman’s breast cancer risk, including:
- Genetic risk factors. You probably know that breast cancer can run in families. Changes in certain genes (including the well-known BRCA 1 and BRCA 2 genes, among others) are known to increase a woman’s risk of breast cancer. However, only about 10% of breast cancers are related to genetic risk.
- Other unmodifiable risk factors. A significant number of breast cancers are related to known factors that can’t be changed, such as being a woman, ethnicity, advancing age, age of your first period, age at menopause, the number of pregnancies you’ve had, and family history of breast cancer (even if you don’t have a known genetic mutation). Women with non-cancerous but atypical breast lesions, known as high-risk proliferative breast lesions, are also at a higher risk of developing breast cancer.
- Modifiable risk factors. These are lifestyle-related factors that we might be able to control, such as diet, weight, physical activity, alcohol use, smoking and extra exposure to estrogen (such as through birth control or hormone replacement therapy).
Reducing Your Risk
It’s good news that so many factors are things that you can change – at any age. Doing your best to establish a healthy lifestyle and maintain a normal body mass index, especially after menopause, can lower the odds of developing breast cancer. Getting regular exercise, quitting smoking and limiting alcoholic beverages can also help cut risk.
Some women may also decide to limit their exposure to estrogen through birth control and hormone replacement therapy. Speak to your doctor about the risks and benefits of these treatments in regard to your breast cancer risk.
For some women at particularly high risk of developing the disease (such as those with a strong family history or those with high-risk proliferative breast lesions), we sometimes prescribe medications to prevent cancer. This is called chemoprevention.
There are two common types of chemoprevention medications for breast cancer:
- Selective estrogen receptor modulators, such as the drugs tamoxifen and raloxifene, work by blocking the action of the hormone estrogen.
- Aromatase inhibitors block the production of estrogen in postmenopausal women.
Chemoprevention Pros and Cons
Several large studies have found that chemoprevention can reduce the risk of both invasive and non-invasive breast cancer by about 50%. (However, some types of breast cancer do not respond to the presence of estrogen, and these drugs do not reduce the risk of those forms of the disease.)
Chemoprevention drugs are usually taken for 5 years total, though their benefit appears to last a decade. In addition to breast cancer prevention, tamoxifen and raloxifene may also improve bone density. In fact, raloxifene is more commonly prescribed as a drug to prevent osteoporosis.
The drugs do come with side effects, however. The most common side effects are postmenopausal symptoms such as hot flashes, night sweats, insomnia and vaginal dryness or thin vaginal discharge.
There are some rarer, though serious, side effects of these medicines as well. Tamoxifen can increase the risk of endometrial cancer, and both tamoxifen and raloxifene can increase the risk of cataracts and blood clots. Aromatase inhibitors are associated with an increased risk of joint pain, cardiovascular disease and high cholesterol, as well as a decrease in bone mineral density that could lead to osteoporosis.
Because of the risk of side effects, chemoprevention medications aren’t right for every woman. But in women at high risk of breast cancer, the benefits of these medications can outweigh the risks. Talk to your doctor about whether they’re right for you.