Incidental Thyroid Cancer in Toxic and Nontoxic Goiter: is TSH Associated with Malignany Rate? Results of A Meta-Analysis

Objective In the last 6 years, several studies reported a positive association between thyrotropin (TSH) and papillary cancer risk. The rationale is based on stimulatory action exerted by TSH on thyroid cell proliferation and/ or progression of a pre-existing papillary carcinoma. To validate this hypothesis, we performed a meta-analysis comparing the incidence of thyroid cancer in 2 groups of patients who underwent surgery for toxic or nontoxic nodular goiter. Methods Using data from 2,150 patients with toxic multinodular goiter (TMNG) and 873 patients with toxic adenoma (TA), the overall incidence of thyroid cancer (and 95% confidence interval [CIs]) was estimated to be 5.9% (3.9 to 8.3) for patients with TMNG and 4.8% (2.5 to 7.9) for patients with TA. Four studies were included in the meta-analysis with a total of 1,964 subjects undergoing thyroidectomy for allegedly benign thyroid disease (520 patients with TMNG or TA and 1,444 for multinodular goiter [MNG] or uninodular goiter [UNG]). Results We did not find any significant differences in the risk of incidental thyroid cancer (ITC) in patients with TMNG versus MNG (odds ratio [OR]: 0.91, 95% CI: 0.47 to 1.77, I4: 62.6%), TA versus uninodular goiter (UNG) (OR: 0.46, 95% CI: 0.12 to 1.79, I5: 12%), and TMNG or TA versus MNG or UNG (pooled analysis) (OR: 0.86, 95% CI: 0.46 to 1.60, I6: 51.5%). Conclusions The results of this meta-analysis did not confirm an association between low TSH values and lower thyroid cancer rate, at least in patients with nodular disease. (Endocr Pract. 2013;19:212-218)