Men, beware! An extra 11cm in waist circumference can increase your cancer risk by 25%, but it’s different for women →

Compiled by: Gong Zixin

Body shape and overweight, usually assessed by body mass index (BMI), are well-established risk factors for several cancers. However, a new study by researchers at Lund University's Malmö Campus in Sweden, published in the Journal of the National Cancer Institute, shows that waist circumference is a stronger risk marker for obesity-related cancers in men, but not in women, compared with BMI. The study will also be presented at this year's European Congress on Obesity (ECO2025, May 11-14).

The study analyzed data collected from a diverse Swedish population of 339,190 individuals who underwent health assessments of BMI and waist circumference between 1981 and 2019 (61% objectively measured, 39% self-reported; mean age 51.4 years). Information on cancer diagnoses came from the Swedish Cancer Registry.

Obesity-related cancers are defined as those for which the International Agency for Research on Cancer (IARC) has concluded that there is sufficient evidence to suggest an association with obesity, and include cancers of the esophagus (adenocarcinoma), stomach (cardiac cancer), colon, rectum, liver/intrahepatic bile duct, gallbladder, pancreas, breast (postmenopausal), endometrial, ovarian, renal cell carcinoma, meningioma, thyroid, and multiple myeloma.

The researchers calculated the relative risks of waist circumference and BMI with respect to obesity-related cancers, taking into account multiple factors that could affect the results, such as age, smoking habits, and sociodemographic factors including education level, income, country of birth, and marital status. Because waist circumference is more difficult to measure accurately and consistently than BMI, its values ​​tend to vary more. To ensure a fair comparison, the researchers adjusted for measurement error in waist circumference and BMI. Finally, because waist circumference and BMI are measured on different scales (1 standard deviation for BMI is 3.7 and 4.3 kg/m2 for men and women, respectively, and 1 standard deviation for waist circumference is 10.8 and 11.8 cm for men and women, respectively), calculating the relative risk for each increase of 1 standard deviation ensured that the increments in waist circumference and BMI were comparable, allowing a direct comparison of the associated relative risks.

During an average follow-up of 14 years, 18,185 cases of obesity-related cancer were recorded. The study showed that in men, an increase of about 11 centimeters in waist circumference (for example, comparing a waist circumference of 100.8 cm to 90 cm) was associated with a 25% increased risk of obesity-related cancer.

In contrast, an increase in BMI of 3.7 kg/m2 (for example, comparing a BMI of 27.7 kg/m2 with a BMI of 24 kg/m2) corresponded to a 19% increased risk.

In addition, after accounting for BMI, high waist circumference remained a risk factor for obesity-related cancers in men. This suggests that the increased risk associated with abdominal obesity is specific and cannot be explained by BMI measurements alone. In women, the association between waist circumference and BMI was weaker but similar. For example, an increase in waist circumference of approximately 12 cm (e.g., comparing waist circumference of 91.8 cm and 80.0 cm) and an increase in BMI of 4.3 kg/m2 (e.g., comparing BMI of 28.3 kg/m2 and 24 kg/m2) were both associated with a 13% increased risk of obesity-related cancers.

"BMI is a measure of body weight but does not provide information about fat distribution, whereas waist circumference is a measure more closely associated with abdominal obesity," the authors explain.

This distinction is critical because visceral fat accumulates around abdominal organs, is more metabolically active, and is associated with adverse health outcomes such as insulin resistance, inflammation, and abnormal lipid levels. Therefore, individuals with similar BMIs may have different cancer risks due to differences in fat distribution.

Regarding the difference between men and women, the researchers believe that a plausible explanation is that "men are more likely to store fat in the viscera, while women generally accumulate more fat subcutaneously and peripherally." Therefore, waist circumference may more accurately reflect visceral fat in men than in women, which may make waist circumference a stronger risk factor for cancer in men but not in women. The researchers suggested that incorporating hip circumference into risk models may further understand this gender difference and strengthen the association between waist circumference and cancer, especially for women. This is because "especially for women, waist circumference and hip circumference combined are better estimates of visceral fat than waist circumference alone." The researchers also explained that studies have shown that obesity, especially central obesity, leads to higher concentrations of circulating insulin in men than in women. This may also partially explain why waist circumference is more strongly associated with cancer risk in men.

"The differences in the associations of waist circumference and BMI with cancer risk between men and women highlight the complexity of the effects of obesity on cancer development. Therefore, it may be helpful to consider biological and physiological differences between sexes when assessing cancer risk, and further research is needed to explore these sex differences."