What are the best ways to prevent breast cancer?

How to Prevent Breast Cancer

To prevent breast cancer, engage in at least 45 minutes of moderate-to-vigorous physical activity on five or more days per week, maintain a healthy weight throughout life, limit alcohol to no more than one drink per day (or avoid it entirely), and consume a plant-based diet rich in vegetables, fruits, and whole grains. 1

Physical Activity: The Most Powerful Modifiable Factor

Physical activity provides the strongest evidence for breast cancer risk reduction among both premenopausal and postmenopausal women. 1

• Engage in 45-60 minutes of moderate-to-vigorous activity on 5 or more days per week for optimal breast cancer risk reduction 1
• Minimum threshold: 30 minutes of moderate activity on 5 or more days per week provides substantial benefit 1
• Vigorous physical activity may decrease breast tissue exposure to circulating estrogen, particularly important for premenopausal women 1
• Physical activity improves energy metabolism and reduces circulating insulin and related growth factors that may promote cancer growth 1

Examples of appropriate activities:

• Moderate intensity: walking, dancing, leisurely bicycling, yoga, gardening 1
• Vigorous intensity: jogging, fast bicycling, aerobic dance, swimming, singles tennis 1

Weight Management: Critical for Postmenopausal Risk

Maintaining a healthy weight throughout life and avoiding weight gain during adulthood is essential, particularly for postmenopausal breast cancer prevention. 1, 2

• Increased body weight and adult weight gain are consistently associated with increased postmenopausal breast cancer risk due to higher estrogen levels produced by adipose tissue 1
• The relationship is weaker for premenopausal breast cancer 1
• Balance caloric intake with physical activity to prevent weight gain 1, 2
• If currently overweight or obese, weight loss is recommended 1

Alcohol Limitation: Clear Dose-Response Relationship

Limit alcohol consumption to no more than one drink per day for women, or avoid it entirely for maximum protection. 1, 2

• Even moderate alcohol intake (more than one drink per day) increases breast cancer risk 1, 2
• The risk is particularly elevated in women with low folate intake 1
• One drink equals: 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof distilled spirits 1
• Total alcohol consumption matters more than the type of alcoholic beverage 1
• The mechanism may involve alcohol-induced increases in circulating estrogens, reduction of folate levels, or direct effects on breast tissue 1

Dietary Patterns: Plant-Based Emphasis

Consume a diet emphasizing plant sources with at least 5 servings of vegetables and fruits daily, whole grains over refined grains, and limited red meat. 1, 2

• Eat 5 or more servings of a variety of vegetables and fruits each day 1
• Choose whole grains in preference to processed (refined) grains and sugars 1
• Limit consumption of red meats, especially those high in fat and processed 1
• While evidence linking specific dietary patterns to breast cancer is weaker than for other cancers, plant-based diets reduce overall cancer risk and cardiovascular disease 1, 3

Breastfeeding: Protective Effect

For women who have children, breastfeeding provides protection against breast cancer, particularly for aggressive subtypes. 4

• Ever breastfeeding (versus never) reduces risk of estrogen receptor-negative and progesterone receptor-negative breast cancers (OR 0.90; 95% CI 0.82-0.99) 4
• Stronger inverse association with triple-negative breast cancer (OR 0.78; 95% CI 0.66-0.91) 4
• Protection appears stronger for BRCA1 mutation carriers than BRCA2 carriers 4

Pharmacologic Risk Reduction for High-Risk Women

For postmenopausal women at high risk of invasive breast cancer, raloxifene is FDA-approved for risk reduction. 5

• Indicated for reduction in risk of invasive breast cancer in postmenopausal women with osteoporosis or at high risk 5
• Contraindicated in women with history of venous thromboembolism 5
• Carries increased risk of venous thromboembolism and death from stroke 5

Risk Reduction Surgery for Very High-Risk Women

Bilateral risk-reducing mastectomy decreases breast cancer risk by at least 90% in BRCA1/2 mutation carriers and should be considered in carefully selected high-risk women. 1

• Appropriate for women with BRCA1/2, TP53, PTEN, CDH1, or STK11 mutations 1
• Meta-analysis shows significant risk reduction (HR 0.07; 95% CI 0.01-0.44) in BRCA1/2 carriers 1
• Requires multidisciplinary consultation before proceeding 1
• Number needed to treat to prevent one breast cancer in high-risk women: 6 1

Avoid Tobacco

Avoid smoking, particularly during adolescence and early adulthood when the developing breast is most susceptible to carcinogenesis. 2, 3

• Emerging data suggest smoking during adolescence or early adulthood increases later breast cancer risk 3

Expected Impact

Successful implementation of these lifestyle modifications could prevent 25-30% of breast cancer cases. 3

Common Pitfalls to Avoid

• Do not assume dietary changes alone will significantly reduce breast cancer risk—the evidence is strongest for physical activity, weight management, and alcohol limitation 1, 3
• Do not recommend hormone replacement therapy for breast cancer prevention—it increases risk 2
• Do not delay implementing lifestyle changes until menopause—protection is strongest when maintained throughout life, starting in adolescence 3
• Do not focus solely on family history—lifestyle factors modify risk in both high-risk and average-risk women 3