What proportion of cancers are attributable to modifiable risk factors?

With more than 20 million new cases and nearly 10 million deaths each year, cancer remains one of the leading causes of morbidity and mortality worldwide, continuing to rise as populations age and certain risk factors spread globally. Among women, breast, lung, and colorectal cancers are the most commonly diagnosed. In men, the most common cancers are lung, colorectal, and prostate cancer. Faced with this reality, public debate often focuses on therapeutic advances, pharmacological innovations, or advances in immunotherapy. However, a significant portion of the global cancer burden is not related to treatment, but to prevention.

For several decades, researchers have known that certain risk factors (tobacco, alcohol, infections, excess body fat, physical inactivity, pollution, and occupational exposure) play a causal role in the development of many cancers. But accurately quantifying their contribution on a global scale remains a complex task. Exposure varies greatly between countries, regions, genders, and levels of socioeconomic development, as do the types of cancer that are most prevalent.

In this context, having robust and comparable estimates of the number of cancers attributable to modifiable factors is a key tool for guiding public health policies. The aim is not to blame individuals, but to understand where the most effective levers for sustainably reducing cancer incidence at the population level lie.

The study

To answer this question, the authors conducted a global analysis of the cancer burden attributable to modifiable risk factors, using data from GLOBOCAN 2022. This database, coordinated by the International Agency for Research on Cancer (IARC), provides harmonized estimates of cancer incidence for 36 tumor sites in 185 countries.

The researchers selected 30 modifiable risk factors, divided into four broad categories: individual behaviors, environmental factors, infectious agents, and occupational exposures. These included smoking, alcohol consumption, high body mass index, insufficient physical activity, certain infections (such as human papillomavirus, Helicobacter pylori, or hepatitis viruses), air pollution, exposure to ultraviolet radiation, and several occupational carcinogens.

To account for the time lag between exposure and cancer development, the authors used exposure prevalence data from approximately ten years prior to 2022. They then calculated population attributable fractions, i.e., the theoretical proportion of cancer cases that would not have occurred if exposure to these factors had been eliminated or reduced to a minimal level of risk. The analyses were performed by gender, cancer type, country, and major world regions, taking into account the overlap between risk factors.

Results & Analysis

The main findings of this study show that globally, of the 18.7 million cancers diagnosed, approximately 37.8% (or 7.1 million new cancer cases) were attributable to modifiable risk factors. There are marked differences between men and women. Among men, the proportion of attributable cancers is significantly higher (45.4% of 9.6 million new cases compared to 29.7% of 9.2 million new cases among women), largely due to greater exposure to tobacco and alcohol in many regions of the world.

However, the historical gap between men and women in terms of tobacco and alcohol consumption is narrowing significantly, especially in high-income countries (North America, Western and Northern Europe).

Smoking appears to be the main modifiable risk factor, accounting for 15% of new cancer cases, particularly lung cancer, but also many other sites. Infections also play a major role (10.2%), particularly in cancers of the stomach, cervix, and liver, with a particularly high burden in certain regions of Africa and Asia. Alcohol (3.2%), excess body fat (2.4%) and insufficient physical activity (1.2%) contribute to varying degrees depending on the region, but together account for a significant proportion of potentially preventable cancers.

A key point in this analysis is the high degree of geographical heterogeneity. Among women in sub-Saharan Africa, 38.2% of newly diagnosed cancers (4 out of 10 cases) are attributed to modifiable risk factors, while in North Africa and West Asia, only 2 out of 10 cancer cases are due to modifiable risk factors. Among men in East Asia, more than half of cancers (57.2%) are attributable to modifiable factors, while in Latin America and the Caribbean, this proportion is significantly lower (28.1%). These differences reflect distinct health, social, and environmental contexts, but also very different opportunities for prevention. In other words, the most effective levers for reducing cancer incidence are not universal, but deeply contextual.

Practical applications

These findings highlight an often-underestimated reality: much of the fight against cancer takes place before diagnosis, well before entry into the healthcare system. Therapeutic advances are essential, but they alone cannot compensate for the massive impact of preventable risk factors, which are largely determined by the environment, public policy, and living conditions.

At the individual level, cancer risk is multifactorial, and exposure to a risk factor never implies a deterministic relationship. On the other hand, at the collective level, these data highlight the importance of structural strategies: tobacco control, policies to reduce alcohol consumption, promotion of physical activity, obesity prevention, vaccination against certain infectious agents (e.g., human papillomavirus), and improvement of air quality.

For government policymakers, this work provides a precise map of prevention priorities by region and population. For healthcare and physical activity professionals, it serves as a reminder that primary prevention, particularly through the adoption of more active lifestyles and the reduction of certain risk behaviors, remains one of the most powerful levers for sustainably reducing the global burden of noncommunicable diseases, including cancer.

Reference

Fink H, Langselius O, Vignat J, Rumgay H, Rehm J, Martinez RX, Santero M, Lopez-Perez L, Inoue M, Zeng H, Shield K, Morgan E, Ilbawi A & Soerjomataram I. Global and regional cancer burden attributable to modifiable risk factors to inform prevention. Nat Med 2026.