Long-term clinical outcomes of papillary thyroid carcinoma patients with biochemical incomplete response

Purpose: The aim of this study was to evaluate the long-term clinical outcomes of papillary thyroid carcinoma (PTC) patients exhibiting biochemical incomplete response (BIR) to initial therapy.

Methods: We evaluated 102 patients with PTC showing a BIR during the first 12-24 months after total thyroidectomy and radioactive iodine therapy. Patients were divided into three groups according to changes in stimulated thyroglobulin (Tg) and anti-Tg antibody (TgAb) levels: the increasing TgAb group (n = 19, 18.6%), the decreasing Tg group (n = 58, 56.9%), and the increasing Tg group (n = 25, 24.5%).

Results: With a median follow-up of 12 years, 43 (42%) patients had structural persistent disease as follows: 36 (84%) at regional sites and 7 (16%) at distant sites. The rate of structural persistent disease was significantly different between groups, with 21%, 41%, and 60% in the increasing TgAb, decreasing Tg, and increasing Tg groups, respectively (P = 0.012). Among patients without structural persistent disease, only 19 (18.6%) showed no evidence of disease and 40 (39.2%) were of a biochemical persistent status at the time of final follow-up. Increasing Tg after initial therapy was a significant risk factor for structural persistent disease in patients with BIR (HR, 4.16; 95% confidence interval (CI): 1.38-12.54, P = 0.011).

Conclusions: PTC patients with BIR showed a high rate of structural persistent disease and Tg change after initial therapy is the most important prognostic factor for determining clinical outcomes of these patients.