By Nancy A. Palermo, MD

Breast cancer is complex. We know inherent risk factors include genetics, life experiences, and exposures from our parents and grandparents.

Our communities and environment can also increase our risk.

What we do know is that the incidence of breast cancer has increased over the past several decades, supporting the importance of understanding modifiable risk factors. Knowing this empowers us to educate ourselves about these risks and do our best to reduce them in our own lives.

This information is meant to empower you to make changes that may reduce your risk. However, even if you follow these recommendations, there is no guarantee you will be protected against the disease.

More importantly, many of the lifestyle changes associated with reducing breast cancer risk also support overall health and well-being, which can help improve our health even when faced with disease.

In the United States, approximately 1 in 8 women will be diagnosed with breast cancer during their lifetime.

While genetics and family history are important, many women diagnosed with breast cancer have no known family history of the disease.

We can address risk factors related to lifestyle, environmental exposures, and overall health.

We can’t change our genes, but we can change our environment and lifestyle, both individually and collectively.

Factors That May Help Protect Against Breast Cancer

1. Physical Activity

Maintaining physical strength and agility into old age is extremely important for overall health and disease prevention. You’ve probably heard the expression “sitting is the new smoking.”

Physical activity is one of the most important lifestyle factors associated with a reduced risk of breast cancer. Exercise at any age is beneficial, and building healthy activity habits during adolescence and early adulthood can provide lasting benefits.

Studies have shown that women who exercise regularly may have approximately a 10–20% lower risk of breast cancer, particularly after menopause.

Physical activity is also important after a breast cancer diagnosis. Research has associated regular exercise with better health outcomes and improved survival among breast cancer survivors.

The more we create opportunities for everyone to exercise safely and consistently, the healthier our communities will be.

2. Pregnancy and Breastfeeding

Pregnancy and breastfeeding can influence breast cancer risk, although the relationship is complex and varies depending on age, timing, and breast cancer subtype.

A full-term pregnancy, particularly at a younger age, is associated with a lower long-term risk of certain types of breast cancer. Multiple pregnancies may provide additional protection.

Breastfeeding is also associated with a modest reduction in breast cancer risk, with longer durations generally associated with greater protection.

There can be a temporary increase in breast cancer risk following childbirth before longer-term protective effects emerge. Importantly, research does not support a causal relationship between abortion or miscarriage and increased breast cancer risk.

These reproductive factors are not always within our control, but understanding their relationship to breast health can help women have more informed conversations with their healthcare providers.

Modifiable Factors That May Increase or Decrease Risk

1. Alcohol

Research strongly links alcohol consumption with an increased risk of breast cancer.

Studies consistently show that breast cancer risk increases with alcohol intake, including at relatively low levels of consumption. A standard alcoholic drink in the United States contains approximately 14 grams of alcohol.

Multiple large studies have found that each additional daily drink is associated with a measurable increase in breast cancer risk. The association is particularly notable for estrogen receptor-positive breast cancers.

The type of alcoholic beverage beer, wine, or spirits does not appear to eliminate this risk.

Alcohol can influence estrogen levels and other biological processes associated with breast cancer development.

Reducing alcohol consumption, or avoiding alcohol altogether, is one practical step women can take to reduce breast cancer risk.

2. Diet and Nutrition

A diet made up primarily of whole, fresh, minimally processed foods supports overall health and may help reduce breast cancer risk.

Vegetables, fruits, dietary fiber, whole grains, nuts, seeds, and plant-based proteins can all be part of simple, nutritious meals.

Try to limit highly processed foods, excess added sugars, and processed meats.

Research continues to examine how dietary patterns, metabolic health, insulin regulation, and inflammation influence breast cancer risk. While the relationship between individual nutrients and cancer is complex, overall diet quality matters.

Fiber-rich vegetables and beneficial plant compounds are especially important.

Consider including:

• Cruciferous vegetables: Broccoli, cabbage, cauliflower, and Brussels sprouts

• Leafy greens: Spinach, kale, and lettuce

• Allium vegetables: Garlic, onions, and leeks

• Colorful vegetables: Carrots, sweet potatoes, and tomatoes

These foods provide fiber, vitamins, minerals, and phytonutrients that support overall health and may help reduce the risk of certain chronic diseases.

3. Breast Density

Increased breast density is an established risk factor for breast cancer.

Breast density refers to the proportion of fibroglandular tissue compared with fatty tissue in the breast. Women with very dense breasts have a higher breast cancer risk than women with predominantly fatty breast tissue.

Dense tissue can also make abnormalities harder to detect on a mammogram.

Factors such as age, genetics, hormonal status, reproductive history, and body composition influence breast density.

While some of these factors may be modifiable, women cannot reliably control breast density through lifestyle changes.

Understanding your breast density and discussing your overall risk with your healthcare provider can help guide appropriate screening recommendations.

4. Chemicals in Everyday Products

We are exposed to numerous chemicals through the products we use, the food we eat, the water we drink, and the environment around us.

Researchers continue to study chemicals such as bisphenol A (BPA), phthalates, PFAS, certain pesticides, and flame retardants because of their potential effects on hormone signaling and human health.

Some chemicals have demonstrated endocrine-disrupting properties, although the strength of evidence linking individual everyday exposures to breast cancer varies.

Reducing unnecessary exposure to potentially harmful chemicals is a reasonable precaution, particularly when safer alternatives are readily available.

5. Ionizing Radiation

Ionizing radiation is an established cancer risk factor, and exposure can come from medical imaging procedures such as X-rays and CT scans, as well as occupational and environmental sources.

Risk depends on factors including radiation dose, age at exposure, and cumulative exposure.

CT scans generally involve higher radiation doses than conventional X-rays, making it important to avoid unnecessary imaging.

However, medically necessary imaging remains an important part of healthcare. Routine breast cancer screening should not be avoided because of concerns about radiation exposure. The benefits of recommended mammography generally outweigh its small radiation risks.

The goal is to make informed decisions and limit unnecessary exposure.

6. Non-Ionizing Radiation

Non-ionizing radiation includes radiofrequency emissions from wireless devices and extremely low-frequency electromagnetic fields associated with electrical equipment and power lines.

Researchers have investigated possible relationships between these exposures and cancer risk, but studies have produced mixed or inconclusive findings.

At present, there is no established causal relationship between typical exposure to cell phones, Wi-Fi, or household electromagnetic fields and breast cancer.

Research continues as technologies and exposure patterns evolve.

7. Tobacco Use

Tobacco smoke contains thousands of chemicals, including many known carcinogens.

Research suggests that smoking, particularly long-term smoking, is associated with increased breast cancer risk. Secondhand smoke exposure may also increase risk.

Smoking can also negatively affect overall health and outcomes following a cancer diagnosis.

If you smoke, quitting is one of the most important steps you can take for your health. Avoiding secondhand smoke exposure is also important.

8. Water and Air Pollution

Environmental exposures are another area of concern.

Industrial chemicals can contaminate drinking water, groundwater, and air. Researchers have investigated links between certain pollutants and breast cancer risk, though evidence varies by chemical and exposure.

One important example is the historical contamination of drinking water at Marine Corps Base Camp Lejeune in North Carolina, where industrial solvents entered the water supply over several decades.

Studies have identified associations between certain exposures at Camp Lejeune and increased risks of several cancers, including male breast cancer.

These findings reinforce the importance of clean water, environmental monitoring, and reducing avoidable exposure to harmful pollutants.

9. Occupational Hazards and Artificial Light

Certain occupations may involve exposures associated with increased cancer risk.

Examples include workers exposed to ionizing radiation, industrial chemicals, pesticides, and other potentially hazardous substances.

Researchers have also investigated the relationship between night-shift work, disrupted circadian rhythms, and breast cancer risk.

Maintaining healthy sleep patterns and minimizing unnecessary occupational exposures can support overall health.

10. Body Weight

Excess body fat after menopause is associated with an increased risk of breast cancer, particularly hormone receptor-positive breast cancers.

The relationship between body weight and breast cancer risk differs before and after menopause and can be influenced by hormonal status and other factors.

Maintaining a healthy body composition through balanced nutrition, regular exercise, and sustainable lifestyle habits is an important part of long-term health.

11. Inflammation

Chronic inflammation is involved in many disease-related biological processes, including cancer development.

Researchers continue to explore how inflammation, metabolic dysfunction, excess body fat, and environmental exposures may influence breast cancer risk.

Researchers frequently study inflammatory markers such as C-reactive protein (CRP), interleukin-6 (IL-6), and other biomarkers in this area.

Regular physical activity, nutritious eating patterns, adequate sleep, and maintaining a healthy body composition can all support healthier inflammatory responses.

12. Vitamin D

Vitamin D plays important roles in bone health, immune function, and other biological processes.

Some observational studies have found associations between low vitamin D levels and breast cancer risk, but the research remains inconsistent.

At this time, vitamin D supplementation has not been established as a reliable strategy for preventing breast cancer.

It is still important to identify and address vitamin D deficiency when appropriate, working with your healthcare provider to determine whether testing or supplementation is necessary.

Your Breast Cancer Prevention Action Plan

Don’t stress! We’ve taken this information and developed a practical action plan to help you make healthier choices.

1. Be an informed consumer. Don’t let greenwashing or pinkwashing mislead you. Read ingredient labels and look beyond marketing claims such as “natural” or “non-toxic.”

2. Focus on whole foods. Build meals around vegetables, fruits, whole grains, nuts, seeds, beans, and other nutrient-dense foods. Aim for a variety of colorful plants and adequate dietary fiber.

3. Review your skincare and personal care products. Become familiar with ingredient labels and consider reducing unnecessary exposure to chemicals of concern.

4. Choose household cleaning products thoughtfully. Use products as directed, ensure proper ventilation, and avoid unnecessary chemical exposure.

5. Limit or avoid alcohol. Even small reductions in alcohol intake can be beneficial.

6. Pay attention to water quality. If appropriate for your water source, consider a certified water filter and replace filters according to the manufacturer’s instructions.

7. Avoid tobacco smoke. Quit smoking if you currently smoke and reduce exposure to secondhand smoke.

8. Reduce unnecessary household exposures. Consider ventilation, dust reduction, and other practical steps to improve your indoor environment.

9. Maintain healthy vitamin D levels. Discuss testing and supplementation with your healthcare provider when appropriate.

10. Support your circadian rhythm. Prioritize consistent sleep, morning daylight, and regular outdoor activity.

11. Avoid unnecessary medical radiation. Discuss the benefits and risks of imaging with your healthcare provider while continuing recommended preventive screening.

12. Maintain a healthy body composition and stay physically active. Focus on sustainable habits that support your metabolic and cardiovascular health.

Breast cancer prevention is not about eliminating every possible risk. It is about understanding the factors we can influence and making informed choices that support our long-term health.

We cannot control everything, but we can take meaningful steps to protect our health—one choice at a time.