Catholic University of Korea tracks early cancer risk across 6 313 338 adults

Researchers from The Catholic University of Korea and affiliated institutions evaluated the link between body mass index, waist circumference, and early-onset cancer risk in young adults using the Korean National Health Insurance Service database from 2009 to 2021 doi.orgAnnals of Internal Medicinedoi.orgOpen source ↗. The nationwide population-based cohort study tracked 6 313 338 individuals aged 20 to 39 years who had no prior cancer diagnosis at baseline. As reported in Annals of Internal Medicine, a total of 151 893 incident cancer cases were recorded during a mean follow-up period of 11.2 years. Body mass index was classified into five categories from underweight to class II obesity based on Asian-specific criteria.

Cumulative incidence rates

The 10-year cumulative incidence of cancer was 1.84% (95% CI, 1.83% to 1.86%) in the normal-weight group, 2.24% (CI, 2.22% to 2.27%) in the class I obesity group, and 2.62% (CI, 2.56% to 2.68%) in the class II obesity group. Compared with the normal-weight cohort, absolute risk differences were 0.40% (CI, 0.39% to 0.41%) for class I obesity and 0.78% (CI, 0.73% to 0.82%) for class II obesity. The relative association was more pronounced in men, whereas absolute risk differences were greater among women.

Body mass index and abdominal measures

Combined evaluations of body mass index and waist circumference showed that individuals with class I obesity and abdominal obesity had a higher 10-year cumulative incidence of 2.45% (CI, 2.41% to 2.50%) compared to 2.13% (CI, 2.10% to 2.16%) for those without abdominal obesity. This rate also exceeded the 2.20% (CI, 2.03% to 2.36%) documented for individuals with class II obesity who did not have abdominal obesity.

By tumor type, the highest cumulative incidence was identified for thyroid, endometrial, and ovarian cancer doi.orgAnnals of Internal Medicinedoi.orgOpen source ↗. Obesity was not associated with an increased risk for breast cancer diagnosed by age 50 years. The authors noted study limitations, including an observational design, a sample restricted to health screening participants, and unmeasured confounding factors such as smoking burden.