Hypercholesterolemia Is an Associated Factor for Risk of Differentiated Thyroid Cancer in Chinese Population.

Background Hyperlipidemia has been hypothesized as a risk factor for thyroid cancer. However, the association between hypercholesterolemia and thyroid cancer is unclear, especially in Chinese population without available published data. We conducted this study to investigate the relationship between hypercholesterolemia and differentiated thyroid cancer (DTC) in Chinese population. Methods Three thousand seven hundred forty-eight patients were enrolled in the study, including 2,021 DTC patients and 1,727 benign subjects with benign thyroid nodules. Demographic characteristics, medical history, and clinical hematological examination were collected. Stratified analyses of association between hypercholesterolemia and risk of DTC were done. Multivariable logistic regression models were used to estimate the association between hypercholesterolemia and the risk of thyroid nodules being malignant. This study protocol was approved by the ethics committee of Shandong Provincial Qianfoshan Hospital and assigned in ClinicalTrials.gov protocol registration and results system (NCT03006289, https://clinicaltrials.gov/ct2/show/NCT03006289). Results The level of serum total cholesterol in patients with DTC is higher than that in benign subjects (P 5.7 mmol/L), the closer the serum total cholesterol level is to normal (3.17-5.7 mmol/L), the less the risk of thyroid nodules being malignant is, and this difference is statistically significant (odds ratio = -0.67, 95% CI (-1.31, -0.03), P = 0.040). However, this difference is not found in the group of patients with lower level of total cholesterol (<3.17 mmol/L, odds ratio = 0.43, 95% CI (-1.22, 2.09), P = 0.068), suggesting that hypocholesterolemia is not a protective factor in the risk of thyroid nodules being malignant. Conclusions Hypercholesterolemia is an associated factor for risk of DTC in Chinese population.