Cumulative exposure to metabolic syndrome increases thyroid cancer risk in young adults: a population-based cohort study.

ABSTRACT

BACKGROUND/AIMS: A re-increasing trend of thyroid cancer since 2015 has been observed despite a similar examination rate, and the incidence of thyroid cancer among young adults continues to rise. METHODS: This study used data from the Korean National Health Insurance Service. Individuals 20-39 years of age who underwent ≥ 4 health checkups from 2009-2013 were enrolled and followed throughout 2019. To quantify the metabolic burden, groups were divided by the number of diagnoses of metabolic syndrome across four consecutive health examinations. RESULTS: Among the study population (n = 1,204,646), 5,929 (0.5%) were diagnosed with thyroid cancer during a follow- up period of 5 years. The hazard ratio (95% confidence interval) values of thyroid cancer occurrence according to the number (1-4) of diagnoses of metabolic syndrome across the four health examinations compared to the group without metabolic syndrome were significantly greater, as follows 1.12 (1.02-1.23), 1.25 (1.10-1.42), 1.33 (1.15-1.55), and 1.48 (1.25-1.75) (p for trend < 0.01), respectively. Each component of metabolic syndrome showed a significant increase in hazard ratio according to the number of diagnoses except for impaired fasting glucose criteria. CONCLUSION: Cumulative exposure to metabolic syndrome was associated with thyroid cancer risk in young adults.