Researchers studied how everyday habits like smoking, drinking alcohol, diet, and exercise affect breast cancer rates around the world from 1990 to 2021. They found that while rates are dropping in wealthy countries, they’re rising in poorer nations. Diet was the biggest lifestyle factor linked to breast cancer, followed by alcohol use, smoking, and lack of exercise. The study predicts these trends will continue through 2035, with more cases expected globally despite lower rates per person. Understanding these patterns helps doctors and public health leaders create better prevention strategies for different communities.

The Quick Take

  • What they studied: How much breast cancer is caused by lifestyle choices (smoking, alcohol, diet, and exercise) and how these patterns are changing around the world
  • Who participated: This wasn’t a traditional study with volunteers. Instead, researchers analyzed data from the Global Burden of Disease Study, which collects health information from countries worldwide covering billions of people
  • Key finding: Diet is responsible for nearly half of all lifestyle-related breast cancer cases, followed by alcohol use (22%), smoking (18%), and lack of physical activity (12%). While rates per person are dropping in wealthy countries, the total number of cases is rising globally because populations are growing and aging
  • What it means for you: Making healthy lifestyle choices—eating well, limiting alcohol, not smoking, and staying active—may help reduce breast cancer risk. However, this research shows that access to healthy options varies greatly depending on where you live and your economic situation

The Research Details

This was a systematic analysis, meaning researchers gathered and analyzed existing health data from many countries rather than conducting new experiments. They used information from the Global Burden of Disease Study 2021, which is one of the largest collections of health statistics in the world. The researchers looked at how many people died from breast cancer and how many years of healthy life were lost due to breast cancer that could be linked to four main lifestyle factors: tobacco use, alcohol consumption, unhealthy diet, and physical inactivity.

The team calculated rates for different regions, countries, age groups, and genders from 1990 through 2021. They also used advanced computer modeling (Bayesian modeling) to predict what might happen through 2035. This approach allowed them to see patterns across time and geography that wouldn’t be obvious from looking at single countries or single years.

The researchers paid special attention to how these patterns differed based on a country’s wealth level, dividing nations into groups from low-income to high-income. This helped them understand whether lifestyle-related breast cancer is a problem everywhere or mainly in certain parts of the world.

This type of large-scale analysis is important because it shows us the big picture of health problems across the entire world. By understanding which lifestyle factors matter most and where they matter most, public health leaders can design better prevention programs. For example, if diet is the biggest risk factor in one region but alcohol is the biggest in another, prevention strategies should be different. This research also helps predict future health needs so countries can prepare resources and plan ahead.

This study used data from the Global Burden of Disease Study, which is widely respected and regularly updated with the latest health information from countries worldwide. The researchers used standardized methods to make fair comparisons across different countries and time periods. However, the quality of health data varies by country—some nations have very detailed records while others have less complete information. The study’s predictions for 2035 are based on current trends, so unexpected changes (like new treatments or major shifts in behavior) could affect accuracy. The study analyzed existing data rather than conducting new experiments, which means it can show associations but not prove that lifestyle factors directly cause breast cancer.

What the Results Show

The research revealed that diet-related factors are responsible for nearly half (48.2%) of all breast cancer cases linked to lifestyle choices. Alcohol consumption accounts for about one-fifth (21.6%) of cases, smoking causes 18.1%, and lack of physical activity causes 12.1%. These percentages show that what we eat has the biggest impact on breast cancer risk among these four lifestyle factors.

When looking at rates per 100,000 people, the researchers found that wealthy countries have higher rates of lifestyle-related breast cancer, but these rates are slowly declining. In contrast, poorer and middle-income countries are seeing rates increase. China had the highest total number of cases (573,281 deaths in 2021), though this is partly because it has a very large population. Western Europe had the highest rate per person.

Globally, the total number of deaths from lifestyle-related breast cancer rose by 65.4% between 1990 and 2021 (from about 76,900 to 125,700 deaths). This increase happened even though the rate per person slightly decreased. This seeming contradiction occurs because the world’s population is growing and people are living longer, so more people are at risk even if the percentage affected is smaller.

The study found that alcohol-related breast cancer showed the biggest differences between regions, suggesting that drinking patterns and alcohol availability vary significantly around the world. This variation offers opportunities for targeted prevention efforts in high-risk areas.

The research showed different patterns for men and women, though breast cancer is much more common in women. The study also found that age matters—breast cancer risk from lifestyle factors increases as women get older. Socioeconomic factors (wealth and education levels) played a role, with wealthier regions generally having higher rates but declining trends, while less wealthy regions showed rising trends. The researchers noted that these patterns reflect differences in lifestyle prevalence (how common smoking, drinking, poor diet, and inactivity are) as well as differences in how well healthcare systems detect and report breast cancer cases.

This is the first study to systematically examine how behavioral risk factors contribute to breast cancer across different wealth levels and cultural contexts worldwide. Previous research has identified these risk factors individually, but this study shows how they combine and vary globally. The finding that diet is the dominant factor aligns with other nutrition research, though the specific percentages provide new detail. The observation that wealthy countries have higher rates but declining trends, while poorer countries show rising trends, reflects broader patterns seen in other chronic diseases as countries develop economically and lifestyles change.

The study relies on health data reported by different countries, and this data quality varies significantly. Some countries have excellent health tracking systems while others have incomplete records, which could affect accuracy. The researchers couldn’t always distinguish between different types of diets or different amounts of alcohol consumption—they worked with broad categories. The study shows associations between lifestyle factors and breast cancer but cannot prove that these factors directly cause the disease. Predictions for 2035 assume current trends continue, but major changes (like new cancer treatments, significant shifts in eating habits, or public health campaigns) could alter the actual outcomes. Finally, the study couldn’t account for all possible factors affecting breast cancer risk, such as genetics, hormone use, or reproductive history.

The Bottom Line

Based on this research, maintaining a healthy diet, limiting alcohol consumption, avoiding tobacco, and staying physically active appear to reduce breast cancer risk. These recommendations align with general health guidelines and are supported by moderate to strong evidence. Women should aim for regular physical activity (at least 150 minutes per week of moderate exercise), eat plenty of fruits and vegetables, limit red and processed meat, and avoid or minimize alcohol. These changes are most effective when started early and maintained throughout life. However, it’s important to note that lifestyle changes reduce risk but don’t eliminate it—genetics and other factors also play important roles.

Everyone should care about these findings, but especially women of reproductive age and beyond, since breast cancer risk increases with age. Women with family histories of breast cancer may benefit most from lifestyle modifications. Healthcare providers should use this information to counsel patients about prevention. Public health officials in low-income and middle-income countries should pay particular attention, as breast cancer rates are rising in these regions and prevention programs could have significant impact. Men should also be aware, as the research shows lifestyle factors affect their breast cancer risk too, though it’s much rarer. People should not assume that healthy lifestyle choices guarantee they won’t get breast cancer—these factors are important but not the only ones involved.

Lifestyle changes typically take time to show health benefits. Most research suggests that maintaining healthy habits for several years may reduce breast cancer risk, though the exact timeline varies by individual. Some benefits of exercise and diet improvements (like better overall health and weight management) appear within weeks to months, but cancer risk reduction typically requires years of consistent healthy choices. The study’s projections suggest that if current trends continue, we’ll see the effects of these patterns through 2035, but individual results depend on personal genetics, overall health, and how consistently someone maintains healthy habits.

Want to Apply This Research?

  • Track weekly alcohol consumption (number of drinks), daily servings of fruits and vegetables, minutes of physical activity per week, and smoking status. Set specific goals like ’limit alcohol to 7 drinks per week’ or ’eat 5+ servings of fruits/vegetables daily’ and monitor progress monthly
  • Use the app to set one lifestyle goal at a time—for example, start by adding 30 minutes of walking three times per week, then gradually add dietary improvements like reducing processed foods. The app can send reminders for exercise, suggest healthy recipes, and track alcohol intake to help users make sustainable changes
  • Create a long-term tracking dashboard showing trends over 3-6 month periods for diet quality, physical activity, and alcohol use. Include milestone celebrations when users reach goals, and use the app’s data to identify which lifestyle factors are easiest and hardest to change, allowing for personalized support

This research analyzes global patterns in lifestyle-related breast cancer and should not be used for personal medical diagnosis or treatment decisions. While the study identifies lifestyle factors associated with breast cancer risk, it cannot prove these factors directly cause cancer in any individual. Breast cancer risk is influenced by many factors including genetics, age, reproductive history, and hormone use—not just lifestyle choices. This information is for educational purposes and should not replace consultation with a healthcare provider. Women concerned about breast cancer risk should discuss their individual risk factors and screening options with their doctor. If you have been diagnosed with breast cancer, follow your oncologist’s treatment recommendations rather than relying on lifestyle changes alone.