Abstract 635: Selenium intake and thyroid cancer: a population-based case-control study in Connecticut
Authors: Wang Qian , Huang Huang , Zhao Nan , Zhang Yawei 
Published: August 2019

Abstract
Objective: Selenium (Se) is an important substrate for thyroid hormones. It is essential in protecting thyroid from free radicals' damage and oxidative stress. Prior studies regarding different Se exposure measurement routes and thyroid cancer risk have shown inconsistent results. And among them, one cohort study conducted among elderly population using dietary Se intake found no association. In the light of fast increasing thyroid cancer incidence in the United States over the past few decades and majority of thyroid cancer patients diagnosed before age 50, we examined the association between daily Se dietary intake and thyroid cancer risk using data from a population-based case-control study in Connecticut in 2010-2011.
Methods: A total of 386 histologically confirmed cases and 433 population-based controls were included. Daily Se intake was calculated using Diet*Calc Analysis Software based on dietary information collected through food frequency questionnaire. Multivariate unconditional logistic regression models were used to investigate the associations between Se intake and the risk of thyroid cancer, by histology and tumor size (microcarcinoma (≤1cm)/macrocarcinoma (&gt;1cm)) after controlling for confounders.
Results: Moderate to high dietary intake of Se was associated with decreased risk of well-differentiated thyroid cancer (OR=0.38, 95%CI: 0.18-0.81 for the third quartile; OR=0.24, 95%CI: 0.07-0.81 for the fourth quartile). Similar results were found among females and papillary carcinomas. The observed protective effect of high Se consumption was only observed for macrocarcinomas (OR=0.21, 95%CI: 0.05-0.93 for the forth quartile) but not microcarcinomas.
Conclusions: In conclusion, our study suggested an inverse relationship between dietary Se intake and well-differentiated thyroid cancer. A stronger inverse association was found for macrocarcinomas. These results warrant further investigation.
Table.Daily Se intake and thyroid cancer risk by histology, gender and tumor size.Daily Se intake and thyroid cancer risk by histology, gender and tumor sizea.Q1 (0.00-81.58)(mcg/day)Q2 (81.58-112.64)(mcg/day)Q3 (112.64-147.89)(mcg/day)Q4 (147.89-)(mcg/day)OverallCases/Controls123/109105/10777/10881/109Adjusted OR (95%CI)1.000.78 (0.44-1.36)0.42 (0.20-0.88)0.30 (0.09-0.99)WomenCases/Controls114/8587/7862/7853/65Adjusted OR (95%CI)1.000.70 (0.38-1.29)0.32 (0.14-0.74)0.20 (0.05-0.78)Women well-differentiatedCases/Controls107/8586/7861/7852/65Adjusted OR (95%CI)1.000.72 (0.39-1.33)0.31 (0.13-0.72)0.18 (0.05-0.70)PapillaryCases/Controls103/10992/10764/10868/109Adjusted OR (95%CI)1.000.70 (0.39-1.26)0.34 (0.15-0.75)0.23 (0.07-0.82)Well-differentiatedCases/Controls116/109104/10776/10880/109Adjusted OR (95%CI)1.000.77 (0.44-1.35)0.38 (0.18-0.81)0.24 (0.07-0.81)Micro-Well-differentiatedCases/Controls66/10948/10728/10838/109Adjusted OR (95%CI)1.000.84 (0.40-1.76)0.34 (0.11-1.04)0.35 (0.06-2.01)Macro-Well-differentiatedCases/Controls49/10956/10747/10840/109Adjusted OR (95%CI)1.000.71 (0.34-1.48)0.46 (0.18-1.16)0.21 (0.05-0.93)a Model was adjusted for age, gender, BMI, education, family history of any cancer, prior benign thyroid disease, total energy intake and alcohol consumption
Note: This abstract was not presented at the meeting.
Citation Format: Qian Wang, Huang Huang, Nan Zhao, Yawei Zhang. Selenium intake and thyroid cancer: a population-based case-control study in Connecticut [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 635.