Obesity And Risk Of Differentiated Thyroid Cancer

Objective:Recently,the incidence of thyroid cancer as well as obesity has dramatically increased worldwide.Whether obesity contributes to the development of differentiated thyroid cancer(DTC)remains controversial.We evaluated the relationship between anthropometric measurements and DTC risk.Method:A large frequency-matched case-control study based on hospital data was performed.A total of 10668 DTC patients and 11858 controls were enrolled.Body mass index(BMI),body surface area(BSA),and body fat percentage(BF%)were calculated.An unconditional logistic regression model was applied.Results:In the analysis of basic characteristics for total population of physical examination,BMI and BSA showed an inverted"V"shape with age,and BF%showed an increase with age.Additionally,the proportion of overweight and obesity in each age group had been gradually increasing trend over the years in both sexes.The univariate analysis showed a significant increase in DTC risk with increased height,weight,BMI,BSA,and BF%.For continuous variables,there was a significant increase in the DTC risk with every 5 cm increase in height,10 kg increase in weight,5 kg/m~2 increase in BMI,0.5 m~2increase in BSA,and 5%increase in BF%.As classification variables,BMI,BSA and BF%were all significantly correlated with DTC risk in a dose-response manner,and higher height and weight also increased DTC risk.It was revealed that the association between the anthropometric measurements and DTC risk was not the same for each subgroup.The multivariate analysis also showed a positive relationship.Based on the Chinese BMI(CN-BMI)classification,for women of all ages,the ORs for overweight and obesity were 1.151(1.037-1277)and 1.292(1.092-1.528),respectively.For men under 50,the ORs were 1.221(1.014-1.469)and 1.520(1.202-1.923),respectively,but the ORs for men over 50 were not significant.It was suggested that BMI was positively correlated with DTC risk in adult males younger than 50 years old.Additionally,BSA showed a significant association for both sexes under 50(P=0.02 and P<0.001).BF%remained significant only for women under 50(P=0.003).However,for both sexes over 50,neither BSA nor BF%was significantly associated with DTC risk.When based on The World Health Organization BMI(WHO-BMI),different association was only observed for men under 50,that is BF%,but not BMI,showed a significant association.Conclusion:In each age stratification for total population of physical examination,the proportion of overweight and obese showed an overall trend of gradual increase over the years,consistent with the reported overweight and obesity rate and increasing trend of China.However,BF%increased with age, regardless of gender.Higher BMI,BSA,and BF%were associated with DTC risk,but with gender and age difference.Importantly,it was observed that BMI was positively associated with the risk of DTC for all patients except for men over 50,and a relatively high BSA was associated with an increased DTC risk for both sexes under 50 years.However,BF%was positively correlated with DTC risk for only women under 50.Broadly,our findings added to the existing evidence suggesting that obesity is a potential independent risk factor for DTC.Obesity intervention might benefit the prevention and treatment of thyroid cancer and probably further relieve the burden of obesity-related cancer.