Association between Hashimoto thyroiditis and clinical outcomes of papillary thyroid carcinoma: A meta-analysis

To assess association between Hashimoto thyroiditis (HT) and clinical outcomes of papillary thyroid carcinoma (PTC).

Databases including Pubmed, Embase, Cochrane Library, and Web of Science were searched. Weighed mean differences (WMDs) and odds ratios (ORs) were used to evaluate association between HT and clinical outcomes of PTC, and the effect size was represented by 95% confidence intervals (CIs). Heterogeneity test was performed for each indicator. If the heterogeneity statistic I2≥50%, random-effects model analysis was carried out, otherwise, fixed-effect model analysis was performed. Sensitivity analysis was performed for all outcomes, and publication bias was tested by Begg's test.

Totally 47,237 patients in 65 articles were enrolled in this study, of which 12909 patients with HT and 34328 patients without HT. Our result indicated that PTC patients with HT tended to have lower risks of lymph node metastasis (OR: 0.787, 95%CI: 0.686-0.903, P = 0.001), distant metastasis (OR: 0.435, 95%CI: 0.279-0.676, P<0.001), extrathyroidal extension (OR: 0.745, 95%CI: 0.657-0.845, P<0.001), recurrence (OR: 0.627, 95%CI: 0.483-0.813, P<0.001), vascular invasion (OR: 0.718, 95%CI: 0.572-0.901, P = 0.004), and a better 20-year survival rate (OR: 1.396, 95%CI: 1.109-1.758, P = 0.005) while had higher risks of multifocality (OR: 1.245, 95%CI: 1.132-1.368, P<0.001), perineural infiltration (OR: 1.922, 95%CI: 1.195-3.093, P = 0.007), and bilaterality (OR: 1.394, 95%CI: 1.118-1.739, P = 0.003).

PTC patients with HT may have favorable clinicopathologic characteristics, compared to PTCs without HT. More prospective studies are needed to further elucidate this relationship.