The value of preoperative antithyroidperoxidase antibody as a novel predictor of recurrence in papillary thyroid carcinoma

The link between chronic lymphocytic thyroiditis (CLT) and papillary thyroid carcinoma (PTC) is widely recognized. Considering the strong association between raised antithyroidperoxidase antibody (TPOAb) and CLT, we postulated that the preoperative TPOAb can predict the prognosis of PTC, particularly for recurrence. A total of 2,070 patients who underwent total thyroidectomy for classical type PTC with tumor size ≥1 cm and with available data on preoperative TPOAb and TgAb were enrolled to compare disease‐free survival (DFS) according to the presence of preoperative TPOAb, TgAb, and coexistent CLT. Patients with positive preoperative TPOAb had a significantly better DFS compared to patients without positive preoperative TPOAb (hazard ratio (HR) 0.53; 95% confidence interval (CI) 0.30–0.94, p = 0.028) while no difference in DFS was found according to preoperative TgAb status. Positive preoperative TPOAb was an independent prognostic factor for structural persistent/recurrent disease after adjustment for major preoperative risk factors such as age, sex, and tumor size (HR 0.52, 95% CI 0.28–0.99, p = 0.048). Although the coexistence of CLT lowered the risk for structural persistence/recurrence in univariate analysis (HR 0.52, 95% CI 0.31–0.86, p = 0.012), it was not an independent favorable prognostic factor by multivariate analysis (HR 0.65, 95% CI 0.38–1.10, p = 0.106). However, when coexistent CLT was combined with positive preoperative TPOAb, it indicated an independent protective role in structural persistent/recurrent disease (HR 0.39, 95% CI 0.16–0.98, p = 0.045). Our study clearly showed that presence of preoperative TPOAb can be a novel prognostic factor in predicting structural persistence/recurrence of PTC. What's new? While chronic lymphocytic thyroiditis (CLT) is generally accepted as a risk factor for papillary thyroid carcinoma (PTC), it is also suspected to protect against PTC recurrence when it coexists with PTC. Our study indicates that coexistent CLT predicts PTC recurrence risk, wherein copositivity for both CLT and preoperative antithyroid peroxidase antibody (TPOAb) is associated with reduced risk of recurrent PTC. In addition, among PTC patients who underwent thyroidectomy, those with preoperative TPOAb positivity had significantly better disease‐free survival than those lacking TPOAb positivity. The findings suggest that preoperative TPOAb and CLT evaluation could help improve accuracy in PTC prognosis.