New Research Links 31 Additional Cancers to Obesity

A new study examining the relationships between body mass index (BMI) and the risk of cancers connected to obesity was published in The Lancet Regional Health – Europe.

Overview
The growing incidence of overweight and obesity highlights the need to clarify how these conditions affect morbidity. There is growing evidence that obesity may be a preventive factor in certain malignancies.

The International Agency for Research on Cancer (IARC) found links between 13 malignancies and BMI in a 2016 research.

A subsequent comprehensive review verified that obesity was a contributing factor in most of these malignancies. Although correlations between BMI and cancer risk have been evaluated by observational research, morphological cancer subtypes have not been the subject of many of these studies.

About the study
The current study assessed the relationships between BMI and obesity-associated cancers and investigated possible cancers and subtypes connected to obesity. The Obesity and Disease Development Sweden study provided the data.

Between 1963 and 2019, the Swedish Cancer Register recorded cancer diagnoses and used codes to categorize malignancies.

The 13 malignancies that the IARC classified as obesity-related were already diagnosed with obesity-related conditions. Furthermore, an exploratory decision algorithm was used to identify probable malignancies linked to obesity. These cancers were characterized as those that had a positive correlation with an increased risk of obesity in comparison to a normal weight or with each 5 kg/m2 increase in BMI.

BMI was evaluated in relation to cancer risk in terms of categories (underweight, overweight, etc.) or, if there were at least 250 or 100 cases, per 5 kg/m2.

95% confidence intervals and hazard ratios (HRs) were calculated using Cox regression models. In addition to being adjusted for baseline age, mode of height and weight assessment, education, birth country, and marital status, the models were stratified by sex and birth year.

For malignancies associated with smoking in individuals who had access to smoking information, Cox models were replicated. To evaluate possible sex interactions, the Wald test was employed.

In conclusion
Overall, the study found 18 possible malignancies linked to obesity that had not previously been linked to fat. These comprised hematological malignancies, malignant melanoma, endocrine system tumors, head and neck, genital, and gastrointestinal tract cancers.

In males, the correlation between BMI and these tumors was marginally weaker than in females, but it was comparable with recognized obesity-related cancers. To validate these results, more research that takes cancer-specific variables into account is necessary.

For more information: Body mass index and risk of over 100 cancer forms and subtypes in 4.1 million individuals in Sweden: the Obesity and Disease Development Sweden (ODDS) pooled cohort study, The Lancet Regional Health – Europe, https://doi.org/10.1186/s12889-024-19767-1