Evaluating the main risk factors of thyroid cancer systematicaly, to provide reference for the further development of thyroid cancer prevention strategies.

Such databases as PubMed, Cochrane Library, CBM, CNKI, VIP and WanFang were searched from the date of their establishment to June 10 2016 to collect the case-control studies on thyroid cancer. After study selection, assessment and data extraction was conducted by two reviewers independently, meta-analysis was performed by using the RevMan 5.1 software.

Nineteen studies involving 4 813 thyroid cancer patients and 6 068 comparions were selected. The results of meta-analysis showed that: the risk factors of thyroid cancer mainly included history of benign thyroid disease [odds ratio (OR)= 7.31, 95% confidence interval (95% CI, 4.37, 12.23)], family history of thyroid cancer [OR= 5.13, 95% CI (3.20, 8.23)], high iodine diet [(marine animal food, OR= 4.15, 95%CI (2.47, 6.99)], CT inspection history [OR= 3.99, 95%CI (2.10, 7.60)], Negative emotions [sulking, OR= 3.31, 95%CI (2.23, 4.91)], BMI greater than 25 [OR= 2.62, 95%CI (1.73, 3.97)], high pressure and anxious [OR= 2.60, 95%CI (1.61, 4.21)], getting along with people not harmoniously [OR= 2.46, 95% CI (1.59, 3.81)], the number of pregnancies of women more than three times [OR= 2.03, 95% CI (1.50, 2.76)], age of menarche less than 13, 14 years old [OR= 1.59, 95% CI (1.06, 2.37)].

Thyroid benign disease history, family history of thyroid cancer, high iodine diet, CT examination, BMI greater than 25, bad mood, social interaction, number of pregnancies and other factors are the independent risk factors for thyroid cancer. Corresponding prevention and control measures should be taken according to these risk factors.

Thyroid neoplasms; Risk factors; Case-control study; Meta-analysis