Potential Risk Factors for Breast Cancer

Cancer is a disease of aging, and it’s estimated that nearly half of all people living in the U.S. will get cancer in their lifetime. A complex range of factors influence each individual person’s risk, including genetics, lifestyle, environmental exposures, and chance.

You’ve probably heard the frequently repeated statistic that one in eight women will get breast cancer. This does not mean that one in eight women in the U.S. have breast cancer right now, but refers to lifetime risk – the likelihood a woman will develop breast cancer during her lifetime. Another way to say this is that seven out of eight women will not get breast cancer in their lifetime.

Although medical experts offer rough estimates of a woman’s risk of breast cancer based on factors such as age and family history, accurately assessing an individual woman’s risk is difficult. There is no perfect way to determine individual risk. Some of the risk factors that are frequently discussed, such as breastfeeding and post-menopausal weight gain, contribute very slightly to an individual’s risk of breast cancer.

The risk of breast cancer goes up as a person ages. A woman in her 40s has a 1 in 65 (1.5%) chance of being diagnosed with breast cancer compared to a woman in her 70s who has a 1 in 25 (4.1%) chance of being diagnosed with breast cancer.

The most common risk factor for breast cancer is being assigned female sex at birth, but people of all genders may also get breast cancer. Even though it is the most common cancer besides skin cancer for women in the U.S., most white women overestimate their risk of breast cancer—one of the unfortunate effects of widespread “awareness” campaigns. Many women also overestimate their risk of recurrence after a breast cancer diagnosis. This can make difficult treatment decisions feel even harder.

Marginalized communities experience extreme disparities in health outcomes for many diseases and breast cancer is no different. Historically, breast cancer mortality rates have been higher for Black women (31%) than any other U.S. racial or ethnic group. While Black women’s incidence rates for breast cancer once were lower than white women in recent years Black women’s incidence rate (127.3) is similar to white women (131.6). Not far behind are Asian-Pacific Islander (95.6), and Hispanic (94.8) women.

When talking about risk of breast cancer, most people immediately think of family history. And many people are surprised to learn that 90% of all breast cancers are not associated with family history. For some families, inherited genes increase the risk of breast and some other cancers. It’s estimated that approximately 1 in 500 women have a harmful (or deleterious) mutation of their BRCA1 or BRCA2 genes. However, inherited BRCA mutations are more frequent among a few ethnic groups, such as Ashkenazi Jews. One in 40 Ashkenazi Jewish women has a cancer-associated BRCA gene mutation.

All people of all genders have BRCA1 and BRCA2 genes, which are tumor suppressor genes that that repair DNA damage that occurs through normal living. Having a harmful BRCA mutation dramatically increases the chance that someone will get cancer over the course of their lifetime, but not everyone with one of these mutations will get cancer. We encourage anyone who is concerned they may have a hereditary risk of breast cancer to seek independent genetic counseling to better understand the risk assessment tools and tests, the full range of options, and what this means for you. Genetic counseling is important not only to help interpret test results, but also to determine which tests are best based on family history and whether genetic testing is right for you.

Increasingly, researchers are turning attention to other gene mutations that may increase the risk of breast cancer. For the most part, these gene mutations are not nearly as well understood or as widely researched as BRCA genes, and therefore much less is known about how much risk is conferred to individuals who have these genetic mutations.

There is a growing body of evidence linking involuntary exposure to chemicals in the environment to increased breast cancer risks.

Lifetime exposures to a range of synthetic chemicals and toxins have been linked to a variety of health harms, including breast cancer. The President’s 2008-2009 Cancer Panel reported that “the true burden of environmentally-induced cancer has been grossly underestimated... [and] the American people—even before they are born—are bombarded continually with myriad combinations of these dangerous exposures.” Yet, very little research funding is devoted to environmental exposures that may increase the risk of breast cancer. Taking environmental exposures seriously challenges the narrative of the mainstream cancer industry that individuals are responsible for developing or preventing breast cancer.

The factors that influence breast cancer risk cannot be isolated and many are beyond individual control. For example, people of color are disproportionality exposed to toxic chemicals that may increase the risk of breast cancer in air, water, and soil pollution. The unequal burden of environmental injustices and racial injustices leads to poorer health outcomes.

Additionally, individual solutions such as shopping for toxic-free products and eating healthy are not equally accessible options for all communities. The focus on individual consumer choices reinforces the narrative that breast cancer risks are within our control, rather than the result of systemic oppressions, structural barriers, and government policies.

It’s easy to believe each person can control their risk of breast cancer by being aware of factors that might raise that risk. As much as we support healthy lifestyles and choices, we also know that there is nothing any of us can do to ensure we never develop breast cancer. Many women who do all the supposedly “right things” still develop breast cancer. Cancer is not your fault!