Clinical evaluation of serum tissue polypeptide specific antigen in patients with thyroid carcinoma

There is no specific marker for diagnosis of thyroid cancer with the exception of carcinoembryonic antigen (CEA) and calcitonin for medullary thyroid carcinoma. Tissue polypeptide antigen (TPA) is known to be a diagnostic marker of malignant neoplasms. TPA is also one of the tumor markers for thyroid cancer, but serum TPA shows poor specificity because of polyclonal antibody. Tissue polypeptide specific antigen (TPS) is detected by the monoclonal antibody M3, directed at 1 of the 35 epitopes in TPA. TPS appears in proliferative tumor cells. We examined 72 patients (32 thyroid carcinoma, 20 thyroid adenoma, 5 adenomatous goiter, and 15 diffuse goiter) and 24 healthy volunteers for serum TPS, TPA, and thyroglobulin (Tg). The TPS in thyroid carcinoma was significantly higher than in healthy controls and thyroid adenoma (p < 0.05). The mean value of TPS for all diseases except thyroid carcinoma was below the cutoff value (95 U/L). The TPS sensitivity, specificity, and accuracy for thyroid carcinoma was 37.5%, 100%, and 64.9% respectively. There were no significant differences in mean values of serum Tg and TPA between thyroid carcinomas and adenomas. Positive rates of tissue TPS expression in thyroid carcinomas and adenomas were 87.5% (7/8) and 14.3% (1/7), respectively. The positive rates for serum TPS and immunoreactive TPS in the tissue correlated significantly (p < 0.0001). It is concluded that TPS is a useful marker for diagnosis of thyroid carcinoma.