Waist circumference may be a more effective risk marker for the development of obesity-related cancers than body mass index (BMI) in male but not female patients, according to new findings presented at the European Congress on Obesity (ECO) 2025.
Background
Body size and excess weight—conventionally assessed using BMI—are well-established risk factors for many types of cancers.
“BMI is a measure of body size but do es not provide information on fat distribution, whereas waist circumference is a proxy more closely related to abdominal adiposity. This distinction is crucial because visceral fat, which accumulates around the abdominal organs, is more metabolically active and has been implicated in adverse health outcomes, including insulin resistance, inflammation, and abnormal blood fat levels. Consequently, individuals with similar BMIs may have distinct cancer risks due to differences in fat distribution,” the study authors explained.
Study Methods and Results
Investigators used Swedish population data to analyze the health outcomes of 339,190 individuals with a mean age of 51.4 years who had undergone health assessments including BMI and waist circumference between 1981 and 2019—61% of which were objectively measured and 39% of which were self-reported. Cancer diagnoses were obtained from the Swedish Cancer Register.
The investigators defined obesity-related cancers as those for which the International Agency for Research on Cancer had concluded there was sufficient evidence linking them to obesity—including esophageal adenocarcinoma, gastric (cardia) cancer, colorectal cancer, hepatic cancer, intrahepatic cholangiocarcinoma, gallbladder cancer, pancreatic cancer, breast cancer (postmenopausal), endometrial cancer, ovarian cancer, renal cell carcinoma, meningioma, thyroid cancer, and multiple myeloma.
When calculating the relative risks associated with obesity-related cancers for waist circumference and BMI, the investigators considered multiple factors that could influence the results: age; smoking habits; and sociodemographic factors such as education level, income, birth country, and marital status.
Because waist circumference is harder to measure accurately and consistently compared with BMI, its values tend to vary more. To ensure a fair comparison, the investigators adjusted for measurement errors in both waist circumference and BMI, thereby making the calculated relative risks of the two measurements more directly comparable. Additionally, because waist circumference and BMI are measured on different scales (1 standard deviation [SD] = 3.7 kg/m² and 4.3 kg/m² for BMI and 10.8 cm and 11.8 cm for waist circumference for male and female patients, respectively), calculating relative risks per 1-SD increase ensured that the increments for both measurements represented comparable magnitudes, allowing for a direct comparison of their associated relative risks.
After a median follow-up of 14 years, the investigators recorded 18,185 established obesity-related cancers. Among male patients, a waist circumference increase of approximately 11 cm was associated with a 25% higher risk of developing obesity-related cancers. By comparison, a BMI increase of 3.7 kg/m² corresponded to a 19% increased risk. After accounting for BMI, high waist circumference remained a risk factor for obesity-related cancer in male patients, suggesting that the elevated risk associated with abdominal adiposity could be specific and not explained by high body size alone—as measured by BMI.
Among female patients, the associations were weaker and similar for both waist circumference and BMI. For instance, both an increase of about 12 cm in waist circumference and an increase of 4.3 kg/m² in BMI were associated with a 13% higher risk of developing obesity-related cancers.
“A plausible explanation is that [male patients] are more likely to store fat viscerally, while [female patients] generally accumulate more subcutaneous and peripheral fat. Consequently, waist circumference is a more accurate measure of visceral fat in [male] than in [female patients]. This may make waist circumference a stronger risk factor of cancer in [male patients] and explain why waist circumference adds risk information beyond that conveyed by [BMI in male patients] but not [in female patients],” the study authors indicated.
Conclusions
“Including hip circumference into risk models may provide further insights into this sex difference and enhance the association between [waist circumference] and cancer, particularly for [female patients]. [T]his is because, especially in [female patients], the combination of waist circumference and hip circumference give a better estimation of visceral fat than waist circumference alone,” the study authors suggested.
Prior research has revealed that adiposity, particularly central adiposity, could lead to higher concentrations of circulating insulin in male patients compared to female patients. This may also partially explain why waist circumference is more strongly associated with cancer risk in male patients.
“The divergence in how waist circumference and BMI relate to cancer risk between [male] and [female patients] underscores the complexity of the impact of adiposity on cancer development. It suggests that considering biological and physiological differences between the sexes might be helpful when assessing cancer risk. Further research is needed to explore these sex differences,” the study authors emphasized.
“Our study provides evidence that waist circumference is a stronger risk factor than BMI for obesity-related cancers in [male patients]. The weaker contribution of [waist circumference] beyond that of BMI in [female patients] may result from sex-specific interactions with adiposity measures, such as with sex hormones, on obesity-related cancer risk, or differences in how waist circumference and BMI reflect body fat in [male] vs [female patients]. Future research incorporating more precise measures of adiposity, along with comprehensive data on potential confounding factors, could further elucidate the relationship between body fat distribution and cancer risk,” they concluded.
