Obesity as an Avoidable Cause of Cancer (Attributable Risks)

Area of Science:

• Epidemiology
• Public Health
• Oncology

Background:

• Excess body weight, encompassing overweight and obesity (body mass index [BMI] ≥25 kg/m²), is a recognized risk factor for numerous adult cancers.
• Given that body weight is modifiable, there is a significant potential for cancer prevention strategies.
• Population Attributable Fraction (PAF) quantifies the burden of excess cancers linked to elevated BMI, estimating avoidable cases.

Purpose of the Study:

• To estimate the global burden of cancer attributable to excess body weight (overweight and obesity).
• To approximate the number of avoidable cancer cases globally due to elevated BMI.
• To compare the proportion of cancers attributable to elevated BMI between sexes and identify key cancer types.

Main Methods:

• Utilized counterfactual methods to calculate the Population Attributable Fraction (PAF) for cancers associated with elevated BMI.
• Analyzed global data to estimate the percentage of new adult cancer cases attributable to elevated BMI.
• Examined variations in PAF by sex and identified specific cancer types most affected.

Main Results:

• An estimated 3.6% of all adult cancers worldwide (≥30 years, 10-year lag) are attributable to elevated BMI, equating to nearly half a million new cases annually.
• Population Attributable Fractions were substantially higher in women (5.4%) compared to men (1.9%).
• Endometrial, post-menopausal breast, and colon cancers collectively represent nearly two-thirds of cancers attributed to elevated BMI.

Conclusions:

• Excess body weight is a major, modifiable risk factor for cancer globally, ranking as the third leading cause after smoking and infection.
• In Western populations like the UK, excess weight is the second leading risk factor for cancer.
• Targeting excess body weight presents a crucial opportunity for global cancer prevention efforts.