Pre-Operative Antithyroid Antibodies in Differentiated Thyroid Cancer

ObjectiveTo evaluate the significance of antithyroglobulin and antithyroid peroxidase antibody levels associated with locoregional metastatic disease in patients with well-differentiated thyroid cancer.MethodsPatients underwent initial treatment for well-differentiated thyroid cancer at our institution between 2014 and 2018. The following variables were collected: age, sex, pre-operative thyroid-stimulating hormone, thyroglobulin, antithyroglobulin antibody (TgAb), antithyroid peroxidase antibody (TPOAb), the extent of surgery, T-stage, N-stage, extrathyroidal extension (ETE), extranodal extension (ENE), lymphovascular invasion, and multifocal disease. The relationships between disease status and pre-operative TPOAb, TgAb, thyroglobulin, and thyroid-stimulating hormone were analyzed.ResultsA total of 405 patients (mean age, 52 years) were included in the study, of which 66.4% were women. Elevated TgAb was associated with the presence of lymph node metastases (LNM) in both the central and lateral neck (P < .01), with a stronger correlation to N1b versus N1a disease (P = .03). The presence of ETE was inversely related to the TgAb titer (P = .03). TPOAb was associated with a lower T-stage (P = .04), fewer LNM (P = .04), and a lower likelihood of ETE (P = .02). From multivariable analysis, TgAb ≥40 IU/mL was an independent predictive factor for a higher N-stage (P < .01 for N0 vs N1; P = .01 for N1a vs N1b), and ENE (P < .01). TPOAb ≥60 IU/mL was associated with a lower T-stage (P = .04 for T <3) and absence of ETE (P = .01).ConclusionElevated pre-operative TgAb was an independent predictor of nodal metastases and ENE, while elevated TPOAb was associated with a lower pathologic T- and N-stage. Pre-operative antithyroid antibody titers may be useful to inform the disease extent and features.