An overall and dose-response meta-analysis for thyrotropin and thyroid cancer risk by histological type

Thyrotropin (TSH) is thought as a risk factor for thyroid cancer. However, the effect of serum TSH might depend on histological types of thyroid cancer. We searched for related studies including serum TSH as an exposure and thyroid cancer as a result in PUBMED, EMBASE and Chinese National Knowledge Infrastructure up to April 21, 2016. This meta-analysis included 22 articles with 53,538 participants. When comparing all histological thyroid cancer, the pooled odds ratios of thyroid cancer in patients with nodules was found to increase significantly with higher serum TSH concentrations for differentiated thyroid carcinoma (1.88 vs .1.48, P = 0.0000) and papillary thyroid carcinoma (2.08 vs. 1.48, P = 0.0006). Each 1 mU/L increase of serum TSH was associated with 14% greater risk of thyroid cancer for all histological thyroid cancer, 16% for differentiated thyroid carcinoma and 22% for papillary thyroid carcinoma. In addition, high serum TSH was associated with a reduced risk for follicular thyroid carcinoma (OR = 0.73, 95% CI: 0.52, 1.02). This meta-analysis suggested high serum TSH concentration is risky for papillary thyroid carcinoma but not for follicular thyroid carcinoma.