Papillary Carcinoma Located in the Thyroid Isthmus

The purpose of the present study was to evaluate the clinicopathologic characteristics and short-term outcomes of papillary thyroid carcinomas (PTC) located in the isthmus compared to tumors located in other thyroid regions, and to use those findings to establish a surgical strategy for treating these tumors. Thyroidectomy was performed in 1,973 thyroid cancer patients in our hospital between January 2006 and December 2007. The patients were analyzed in two groups; group I, patients with tumors located in the isthmus (n = 181) and group II, patients with tumors located in other thyroid regions (n = 1,792). The clinicopathologic characteristics and short-term outcomes were compared between the two groups. The study groups were similar in terms of age and gender ratio. For groups I and II, respectively, the mean primary tumor size was 1.02 cm and 1.13 cm (p = 0.017), capsular invasion frequency was 70.2 and 60.8% (p = 0.008), and multifocality frequency was 48.6 and 39.8% (p = 0.006). In addition, central node involvement was 40.3 and 42.1% (p = 0.350), and lateral node involvement was 9.4 and 18.2% (p = 0.001). At the time of postoperative iodine-131 remnant ablation, 34.3% of group I patients and 38.0% of group II patients showed undetectable serum thyroglobulin concentrations. There were no significant differences in surgical complications between the two groups. Papillary thyroid carcinomas located in the isthmus was more likely to be associated with multiple foci in bilateral lobes and higher rates of capsular invasions than tumors in other thyroid regions. These findings indicate that total thyroidectomy is an appropriate initial surgical procedure for the isthmic PTC.