Introduction/Background Apart from BMI, abdominal obesity is currently being investigated as an indicator of adiposity and endometrial cancer risk, and its prevalence among young women has been increasing. This study aimed to investigate whether persistent abdominal obesity exposure is associated with an increased risk of endometrial cancer in young women.

Methodology In this large-scale prospective cohort study, we used data from the South Korean National Health Insurance Service between 2009 and 2012. A total of 445,791 participants aged 20–39 years, who completed four consecutive annual health check-ups and had no history of any cancer, were included. The participants were categorized into five groups based on exposure scores of abdominal obesity (waist circumference ≥85 cm) over four years: 0, 1, 2, 3, and 4. The primary outcome was newly diagnosed endometrial cancer, and the cohort was followed up until December 2020. The Cox proportional hazards regression model was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for incident endometrial cancer.

Results At a median follow-up of 7.12 years, 302 patients were diagnosed with endometrial cancer. The cumulative incidence of endometrial cancer was significantly different based on exposure scores of abdominal obesity (log-rank test, P <0.001). The incidence rate and HRs of endometrial cancer increased significantly with greater exposure scores of obesity. Multivariable-adjusted HRs for incident endometrial cancer were 1.480 (95% CI, 0.970, 2.258), 2.361 (95% CI, 1.391, 4.008), 4.114 (95% CI, 2.546, 6.647), and 6.215 (95% CI, 4.250, 9.088) for participants with scores of 1–4, respectively, compared to those with exposure score of 0.

Conclusion We found that the risk of endometrial cancer significantly increased with cumulative exposure to abdominal obesity among young women in a graded dose-response manner. In particular, persistent being obese for four consecutive years was strongly associated with an increased risk of endometrial cancer.

Disclosures Authors have no conflict of interest to declare.