Understanding Risk Factors for Breast Cancer

There are steps all women can take to reduce their chances of developing breast cancer.

It is not possible to completely eliminate your chances for developing breast cancer, but there are steps you can take to reduce risk. Some risk factors, like age and genetics, cannot be changed. However, certain lifestyle choices can help you to prevent breast cancer and there are steps you can take to minimize risk associated with factors you have no control over.

This post is the first in a Breastlink series on breast cancer risk and prevention. Here, we will go over some of the risk factors that affect your chances of developing breast cancer and provide an overview of what you can do to prevent breast cancer.

What are the risk factors for breast cancer?

As previously mentioned, there are some risk factors that you can change and others that you cannot change. Women should take steps to understand their risk in order to make decisions that promote their overall health and reduce their risk for developing breast cancer.

Risk factors you cannot change

Age

Risk for developing breast cancer develops with age, with approximately two-thirds of all invasive breast cancers affecting women age 55 and older.

Genetics

Certain inherited genetic mutations, such as those occurring in the BRCA1 and BRCA2 genes, increase a woman’s lifetime risk for developing breast cancer.

Between 55 and 65 percent of women with a harmful BRCA1 mutation and approximately 45 percent of women with a harmful BRCA2 mutation will develop breast cancer by the age of 60. Risk increases in women with a harmful mutation to both genes. By contrast, the risk for an average woman with no risk factors is 7 to 12 percent.

It is important to realize there are other genes besides BCRA1 and BCRA2 that also increase risk. Just a few of these are Palb2, CHEK2 and ATM. More genes linked to increased risk for breast cancer will likely be identified as our understanding of hereditary cancer syndromes develops.

Family History

Approximately 10 percent of breast cancer cases could be hereditary, meaning they are the result of genetic mutations inherited from a parent. For this reason, women with a first-degree relative (i.e. a sister or mother) diagnosed with breast cancer are considered at higher risk than women with no family history of breast cancer.

Also, if there is cancer on the paternal side, we need to look at the 2nd and 3rd degree relatives to get an accurate history. Remember that 50 percent of our genes come from our father.

Race & Ethnicity

Your race or ethnicity may represent a risk factor. For instance, Asian and Hispanic women have a lower risk than white and black women. Additionally, there are higher rates of premenopausal breast cancers among black women and breast cancer mortality rates are highest among black women, although white women have a higher lifetime risk for developing breast cancer.

Inherited BRCA1 and BRCA2 mutations are also more prevalent among certain ethnicities and populations, particularly women of Ashkenazi Jewish heritage.

History of Radiation to Chest Wall

Women who received radiation therapy to the chest area in their youth, generally as a treatment for another cancer, have a higher lifetime risk for developing breast cancer.

Previous Breast Cancer Diagnosis

Women previously diagnosed with breast cancer are also 3 to 4 times more likely to develop a new breast cancer than a woman who has never had cancer.

Menstruation

Due to the relationship between breast cancer and production of estrogen and progesterone, women who begin menstruation at a younger age or who experience menopause later have a higher lifetime risk for develop breast cancer.

Other factors

Women with dense breasts may have a higher risk for developing cancer than women with less dense breasts. Certain breast lesions also seem to be associated with a higher risk for developing breast cancer.

Risk Factors for Breast Cancer You Can Change

Obesity

While the connection between weight and breast cancer risk is still not fully understood, research shows that obesity can contribute to a woman’s lifetime risk for developing breast cancer, particularly after menopause. This is possibly because, after menopause, most estrogen comes from fat tissue. Also insulin resistance, or pre-diabetes, and diabetes may increase the risk for breast cancer.

Physical Activity

There is also evidence growing that physical activity and exercise can help to reduce lifetime risk for developing breast cancer. One study suggested that just 2.5 hours per week of brisk walking could reduce breast cancer risk by 18 percent while 10 hours per week further reduced risk.

Alcohol & Tobacco Use

There is a clear link between alcohol use and risk for developing breast cancer.

• Women who limit alcoholic drinks to 1 per day have a very slight increase in risk.
• Women who drink 2 to 5 drinks daily are approximately 1.5 times more likely to develop breast cancer than women who don’t drink alcohol.

These studies show the risk is the same for beer, wine or hard liquor. Additionally, recent research suggests a link between increased risk for breast cancer and heavy smoking.

Childbirth

Some studies show a link between breast cancer risk and exposure to estrogen, according to the National Cancer Institute. Because pregnancy reduces estrogen production, a woman’s age at time of first birth and number of pregnancies may have an effect on breast cancer risk.

Birth Control

Women who use certain forms of birth control may be at higher risk for developing breast cancer than women who do not use birth control due to the presence of hormones in these drugs.

Postmenopausal Hormones

Hormone therapy following menopause, although potentially helpful in the treatment of postmenopausal symptoms, increase a woman’s risk for developing breast cancer. Using hormone therapies combining estrogen and progesterone can increase a woman’s risk for developing and dying from breast cancer in as little as two years and certainly if used for more than seven years.

Hormones using just estrogen does not appear to be linked to an increased risk for breast cancer. However, they may be linked to an increased risk for uterine cancer and ovarian cancer in women who still have their uterus, as well as to blood clots, stroke and heart disease.

Breastfeeding

Due to the relationship between estrogen production and breastfeeding, breastfeeding for between 1.5 and 2 years may help to reduce lifetime risk for developing breast cancer.

Other factors

Some additional factors linked to a potential increased risk that you can change include night work, chemicals in the environment and a diet high in fat and animal protein.

Understanding risk & engaging in healthy habits helps to prevent breast cancer

Understanding your personal risk will help you to make lifestyle decisions and health care choices that fit your priorities while helping to prevent breast cancer. To help women better understand their breast health, risk assessment programs are offered by health care organizations, including Breastlink, across the country and many health insurance plans cover all or some of the associated costs.

Before making drastic decisions about ways you can prevent breast cancer, be sure to consult with a physician who is well versed in assessing an individual woman’s risks for breast cancer and who can advise you on the degree of prevention that any potential intervention will provide. Women can take some steps on their own by, for instance, engaging in regular exercise and maintaining a healthy weight.

However, many of the risk factors that you can change involve highly personal decisions, like when to give birth, whether to take birth control and whether to seek preventative treatments. Women should take steps to understand how these changes can affect their lives and consult with her health care team in order to make informed choices for her health.