Anti-thyroid antibodies as a predictor of thyroid cancer

Recent literature has suggested an association between autoimmune thyroiditis and papillary thyroid cancer. The aims of this study were to evaluate if positive thyroid antibodies are associated with thyroid carcinoma and to examine the role of thyroid antibodies in the management of thyroid nodules.

This is a database study of all patients undergoing thyroidectomy with recorded preoperative thyroid antibodies (autoantibodies to thyroglobulin and/or thyroid peroxidase) levels from 2010 to 2012. We analysed preoperative thyroid antibody levels, fine needle aspiration cytology (FNAC) results, type of thyroid surgery and final histopathology.

There were 960 patients who underwent thyroidectomy with recorded preoperative thyroid antibodies. Of 960 patients, 784 had preoperative FNAC of thyroid nodules. Final histopathology showed 758 benign and 202 malignant cases. As expected, there was a strong association between raised thyroid antibodies and lymphocytic thyroiditis on histology (P = 0.0001) (two-sided probability). Overall, positive thyroid antibodies were not found to be a predictor of thyroid carcinoma (P = 0.161) (two-sided probability). However, in patients with benign FNAC, positive thyroid antibodies increased the risk of thyroid malignancy (odds ratio 2.16; 95% confidence interval 1.11 to 4.21, P = 0.027) (two-sided probability).

Patients with positive thyroid antibodies have a greater risk of malignancy in those with benign FNAC. We recommend routine thyroid antibody assessment in addition to FNAC as part of the assessment of thyroid nodules.