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Abstract Background Obesity is recognized as a risk factor for various cancers, including thyroid cancer. However, the association between different metabolic obesity phenotypes and thyroid cancer risk remains unclear. This systematic review aimed to comprehensively evaluate the existing literature to elucidate the association between metabolic obesity phenotypes and thyroid cancer risk. Methods This systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines. PubMed, Scopus, EMBASE, Web of Science, and Google Scholar were searched for relevant studies until April 2024. Studies examining the link between metabolic obesity phenotypes and thyroid cancer risk were included. Results Five cohort studies involving 831,510 participants met the inclusion criteria. Metabolically unhealthy obesity was consistently associated with an increased risk of thyroid cancer in both men and women. Central adiposity emerged as a significant predictor of thyroid cancer risk. Mechanistically, chronic inflammation, dysregulated adipokine secretion, hormonal imbalances, and altered signaling pathways may contribute to thyroid carcinogenesis. There is an ongoing debate regarding the risk associated with metabolically healthy obesity, with some suggesting potential protective effects due to favorable metabolic profiles. Conclusion This systematic review highlights the complex relationship between metabolic obesity phenotypes and thyroid cancer risk. The findings highlighted the importance of considering metabolic status alongside obesity in thyroid cancer risk assessment and intervention strategies.

BackgroundThis study aimed to determine the association between different weight histories, including cumulative excess weight, cumulative excess waist circumference (WC), duration of general and central adiposity, current and maximum body mass index, and current and maximum WC, and incident coronary heart disease (CHD) and stroke. Methods and ResultsThe study population consisted of 4398 adults aged ≥40 years without CHD or stroke at baseline. Associations between different weight histories and CHD and stroke were determined by multivariable time‐varying Cox regression models after adjustment for age, sex, and time‐varying confounders. Further adjustment was also done for mediators (eg, diabetes mellitus, hypercholesterolemia, and hypertension). During median follow‐up of 13.9 years, 718 incident CHD and 158 stroke events were documented. Multivariable adjusted hazard ratios (HRs) were calculated in the sex and confounder adjusted model for CHD per 1‐SD increase in cumulative excess weight (HR: 1.02; 95% confidence interval [CI], 0.96–1.07), cumulative excess WC (HR: 1.14; 95% CI, 1.04–1.24), duration of general adiposity (HR: 1.00; 95% CI, 0.92–1.08), duration of central adiposity (HR: 1.01; 95% CI, 0.93–1.09), current body mass index (HR: 1.03; 95% CI, 0.99–1.07), current WC (HR: 1.21; 95% CI, 1.11–1.32), maximum body mass index (HR: 1.01; 95% CI, 0.95–1.07), and maximum WC (HR: 1.17; 95% CI, 1.07–1.28). After further adjustment for mediators, current and maximum WC still showed a significant risk (HR: 1.13 [95% CI, 1.03–1.23] and 1.09 [95% CI, 1.00–1.20], respectively). Moreover, in the sex and confounder adjusted model, cumulative excess WC and maximum WC were associated with higher risk of stroke (hazard ratio: 1.21 [95% CI, 0.99–1.48] and 1.25 [95% CI, 1.02–1.55], respectively). ConclusionsExposure to cumulative excess weight and cumulative excess WC confers little additional risk beyond their current and maximum values. Even current and maximum WC were associated with incident CHD in the presence of obesity mediators, and the latter was a significant predictor of stroke in the presence of confounders.