Young men with overweight, obesity at greater risk of developing cancer

Higher body mass index (BMI) may increase the risk of developing site-specific cancers in young men, reveals a recent study.

Such malignancies include malignant melanoma, leukaemia, myeloma, Hodgkin lymphoma, non-Hodgkin lymphoma, and cancers in the lungs, head and neck, central nervous system (CNS), thyroid, esophagus, stomach, pancreas, liver and gallbladder, colon, rectum, kidney, and urinary bladder.

“These results could be used in public health policymaking, further strengthening the incentive for public health effort in reversing the obesity epidemic in children and adolescents,” the investigators said.

This population-based cohort study measured height and weight of participants at age 18 years. The investigators used Cox regression models to evaluate linear associations for BMI and included age, year, and site of conscription, as well as parental level of education as covariates.

A total of 1,489,115 men were included in the primary analyses. Of these, 78,217 developed cancer during a mean follow-up of 31 years. [Obesity 2024;32:376-389]

BMI showed a linear relationship with the risk of developing site-specific cancers, namely malignant melanoma, leukaemia, myeloma, Hodgkin lymphoma, non-Hodgkin lymphoma, as well as cancers in the lung, head and neck, CNS, thyroid, esophagus, stomach, pancreas, liver and gallbladder, colon, rectum, kidney, and bladder.

In some instances, the increased risk was observed in BMI levels considered as normal (20‒25 kg/m²). On the other hand, higher BMI correlated with a reduced risk of prostate cancer. Gastrointestinal cancers were found to have the highest hazard ratios and population attributable fractions.

IARC statement

“In this young population, we were able to confirm the associations between higher BMI in adulthood and higher risk for site-specific cancers indicated by the International Agency on Research on Cancer (IARC) as related to obesity and show that these associations are independent of cardiorespiratory fitness,” the investigators said. [N Engl J Med 2016;375:794-798]

The associations with other types of cancer were also previously observed in an Israel study but with no consensus for BMI in neither youth nor adulthood in the IARC statement. [Lancet Diabetes Endocrinol 2020;8:216-225]

“Our results were similar for cancer in the stomach, colon, rectum, pancreas, prostate, kidney, brain, and thyroid as well as for Hodgkin and non-Hodgkin lymphomas, multiple myeloma, leukaemia, and malignant melanoma,” the investigators said.

However, the Israel study found that BMI was inversely associated with lung cancer and showed trends toward reverse associations for cancers in the esophagus and liver and gallbladder. In the current study, a linear risk was seen to increase with increasing BMI.

“Neither the IARC statement nor the Israeli study have reported associations between body weight and cancer in the CNS or urinary bladder,” according to the investigators.

In an earlier systematic review, associations between BMI and any brain tumour were described, including malignant tumours and meningiomas. No significant association was observed for obesity, but there was a slight increase for malignant tumours with overweight. [Eur J Clin Nutr 2016;70:757-765]

“Our results indicate some future research directions, first to confirm the results for cancer sites that have not been previously reported, second to clarify the effect of body fatness on cancer in different periods of life, and third to establish whether a higher risk of developing cancer also translates into a higher mortality after being diagnosed with cancer,” the investigators said.