I’ve always assumed I was at exceptionally low risk for breast cancer. I never smoked, I’ve never been overweight, I eat healthily, and I’ve been exercising almost daily for decades. I don’t have any family history of breast cancer, and I’ve never missed a mammogram. My annual scans had all been reassuringly negative—until the one I had two years ago, at age 48, that led to my diagnosis of stage I breast cancer: estrogen receptor–positive, HER2-negative.
At first I thought it was a mistake. Then I thought I must be one of those one-in-a-million bad-luck cases. I’ve since learned that I’m not all that special. According to the Breast Cancer Research Foundation, only around 5 to 10 percent of all breast cancers are hereditary. (However, in women under 30, genetic factors may account for 25 percent of breast cancers.)
You must be thinking what I was thinking: If most women diagnosed with breast cancer have no family history, then what the hell is going on? How can any woman understand where her risks lie, and what she can do about them?
What I’ve learned from talking to my own doctors and several nationally renowned experts is that the question of cancer risk is ridiculously complicated. If we knew how to definitively squash nongenetic risk factors, breast cancer rates would be dwindling to almost zero instead of ticking up by 1 percent per year (1.4 percent in women under 50, like me). But we’re learning more every day about the factors that elevate our risk, including findings that shed a little light on cases like mine. And evidence has emerged that there are meaningful steps women can take to lower our risk, even if they’re not foolproof.
The Limited Role of Genes
The mechanistic process from gene mutation to metastasis is far from straightforward. Take the BRCA1 and BRCA2 genes, which are well known for their association with breast cancer. Everyone has two copies, one from each parent. These genes produce proteins that help repair damaged DNA and keep breast, ovarian, and other cells growing normally. According to Judy Garber, MD, MPH, the chair and chief of the Division of Cancer Genetics and Prevention at Dana-Farber Cancer Institute and a professor of medicine at Harvard Medical School, the main job of these genes is to help correct the mistakes cells inevitably make when they’re reproducing.
“If you have a mutation in one of the BRCA genes that prevents it from finding those mistakes and fixing them, then it’s possible for errors to accumulate and for cancer to develop,” says Dr. Garber. More than 60 percent of women who inherit a harmful mutation in BRCA1 or BRCA2 will develop breast cancer during their lifetime, compared with about 13 percent of women in the general population.
But BRCA gene mutations aren’t the only red flags. People have around 20,000 protein-coding genes, Dr. Garber explains, and some of them may have very subtle roles in actions like metabolizing carcinogens or hormones. We inherit many different combinations of genes from our parents, and various lesser-known combinations bring as much risk as a BRCA gene mutation. These genetic factors contribute to a woman’s personalized risk score, Dr. Garber says.
After my diagnosis, I underwent a genetic risk assessment that looked for 71 genes associated with cancer. I tested negative for every single one. “No clinically significant variants detected,” read my report. Yet here I was, with breast cancer—because there are other reasons that cells can go wrong.
The Risks Within and Around Us
Every time a cell divides, things can go awry. By the time we reach our 60s, we’ve had a lot of chances to rack up random errors and accumulate harmful mutations that build upon one another. That’s why age is considered the biggest risk factor for cancer, and why so many older people are eventually diagnosed with at least one cancer.
Cells can also change due to an environmental trigger, says Mary Beth Terry, PhD, a professor of epidemiology and environmental sciences at Columbia University and the executive director of the Silent Spring Institute, a scientific research organization dedicated to studying environmental factors in women’s health. Terry says that because people who survived the atomic bomb attacks on Hiroshima and Nagasaki were exposed to such a high amount of radiation, they are much more likely to develop cancer at a younger age than the general population.
Research by Terry and her team shows that people born in the late 1980s or 1990s have progressed to metastatic disease faster than previous generations, and they tend to have a higher incidence of cancer overall. This can’t be explained by better and more proactive screening, Terry says, since people under 40 don’t tend to get routine mammograms unless they have a concerning family history. Terry and other scientists argue that the difference is in the environment: People are being exposed to more harmful chemicals and toxic substances in their daily lives.
“There’s no [other] reason that the number of times cells in your breast should differ between someone who was born in the ’50s, ’60s, ’70s, or ’80s,” Terry says. “But we see a distinct pattern when we’re looking at those cohorts. Each successive cohort is getting more cancer, and more aggressive cancer.”
Many women get breast cancer despite having done everything right.
Quantifying environmental exposure is challenging, but Terry says new methods developed in the past few years are helping researchers examine chemicals, how people are exposed to them, and the amounts in the body. In a study published in 2024, Silent Spring identified more than 900 chemicals that could increase the risk of breast cancer, and other studies by the organization’s scientists have found chemicals associated with cancer in pesticides, plastics, household air and dust, consumer products, and drinking water. Being constantly exposed to low levels of chemicals every day can lead to a concerning sustained exposure over time.
The biggest concern is endocrine-disrupting chemicals that can interfere with hormone-signaling pathways and mammary gland development. Some examples of endocrine disruptors are parabens in lotions and shampoos, phthalates in vinyl (which you may have as flooring or siding in your home), and PFAS (per- and polyfluoroalkyl substances, also called “forever chemicals”) in food packaging.
Terry says there are vulnerable periods when the breast tissue is in the process of changing, such as during puberty, pregnancy, and breastfeeding, when exposure to these endocrine-disrupting chemicals can be especially influential on future cancer risk. She’s currently working on a study that shows some of the chemicals in personal care products are correlated with higher breast density in teenage girls. “I think people were able to dismiss the earlier studies showing a link between chemicals and cancer because most of them were done in older women,” she says. “But once you start homing in on what’s going on in younger women, the evidence is much more consistent, and it goes beyond just a single type of chemical.”
Talking to Terry made me realize just how much casual exposure I had to carcinogens in my youth. I grew up in southeastern Massachusetts and spent summers on Cape Cod, locations known to have higher breast cancer incidence rates. Among the possible risk factors are air and water pollution associated with a local military base (down the street from our vacation cottage), pesticide applications to cranberry bogs (down the street from my childhood home), particulate air pollution from a large electric power plant, and contaminated drinking water. Also suspect is the area’s once-booming textile industry, which may have leached chemicals into the water supply. There are no conclusive links between these factors and my cancer, but there are definitely reasons to raise an eyebrow at my old assumption of being risk factor–free.
Taking Back Control Where We Can
We obviously can’t undo the past, but we can take steps to limit our future exposure as well as that of our children. The Silent Spring Institute offers many helpful resources, such as a free mobile app called Detox Me that provides research-backed tips for avoiding toxic chemicals. (It comes with a barcode scanner that flags potentially harmful ingredients in household products and suggests safer swaps.)
Hold the government accountable, too. “Upstream policy and regulation [which target the root cause of the issue], as with tobacco control, are the most effective ways to reduce the burden from environmental carcinogens,” Terry says. We can all track bills and advocate with our local, state, and federal representatives for more stringent government action. Check out Safer States, a national alliance of environmental health organizations working to safeguard people from toxic chemicals through advocacy.
We can also make sure to prioritize those fundamental healthy habits that have been drilled into us. Marian Neuhouser, PhD, RD, a nutritional epidemiologist who leads Fred Hutch’s Cancer Prevention Program, recommends the following: Maintain a healthy weight, stop smoking, lower alcohol intake, exercise daily, and get a good night’s sleep (fragmented sleep is emerging as a potential cancer risk factor, she said). Neuhouser notes that there’s solid research behind all of these obvious-sounding ways to lower one’s breast cancer risk.
The point that intrigues me the most is about weight maintenance. “Adipose tissue is more than just a storage site; it’s an active endocrine organ,” Neuhouser tells me. “While it’s busy metabolizing, it sends out lots of signals to cells. Some of those signals are related to telling cells to grow, including perhaps precancerous breast cells. Adipose tissue also secretes pro-inflammatory cytokines that can create a favorable environment for tumor growth.”
There isn’t a breast cancer–specific diet, but Neuhouser says that many of the healthy dietary patterns that work to prevent health issues like hypertension or diabetes (such as the DASH diet) can also reduce breast cancer risk. These diets tend to have things in common, like being rich in whole grains, fresh fruits and vegetables, lean protein, and low-fat dairy.
Most of these healthy eating patterns exclude alcohol, which is a leading modifiable risk factor for breast cancer. (In fact, data shows that 16.4 percent of breast cancer cases are specifically linked to alcohol consumption.) With all of the research coming out about the connection between alcohol and cancer, I now know that consuming even one drink a day can increase breast cancer risk by 7 to 10 percent, and I used to have at least one drink on weekend days. Alcohol breaks down into acetaldehyde, which damages DNA and potentially deregulates cell growth. Alcohol also increases estrogen levels in the body, which can encourage the development of estrogen-fueled breast cancers like mine over time.
My conclusion? There’s unfortunately no silver bullet to preventing breast cancer. All women have some risk of developing it, Dr. Garber says, simply by virtue of having breasts. “Many women get breast cancer despite having done everything right,” she says.
That doesn’t mean a diagnosis is inevitable, or that we should give up on protecting our health. Dr. Garber emphasizes that those boring-but-important behaviors (exercising, eating healthily, avoiding alcohol, and sleeping well) reduce your risk of not only breast cancer but of colon cancer, cardiovascular disease, Alzheimer’s disease, and a host of other health issues. “You’re increasing your chances of staying healthy and feeling good across the board,” she says. That’s motivation for me, at least, to cut my losses and focus on living as healthy a life as I can.
Member Exclusive: Read Our Trending Wellness Stories
Corrie Pikul is the Health and Wellness Director of O, The Oprah magazine, where she covers every aspect of health, from mood to the microbiome, the immune system to the cardiovascular system, sex to sleep.