The Clinical Importance of Minimal Extrathyroid Extension on Tumor Recurrence in Patients with Papillary Thyroid Carcinoma

ABSTRACT

BACKGROUND: We wanted to evaluate whether a minimal extrathyroid extension (METE) is associated with the clinicopathological parameters that are indicative of a poor prognosis, including lymph node metastasis, distant metastasis at the time of the initial diagnosis and tumor recurrence, in patients with papillary thyroid carcinoma (PTC), and especially in the patients with papillary thyroid microcarcinoma (PTMC). METHODS: We retrospectively evaluated the medical records of patients with PTC and who had undergone total thyroidectomy with/without subsequent 131I remnant ablation at the Korea Cancer Center Hospital from January 1998 through December 2005. A total of 557 patients with PTC were enrolled in the study. We excluded 13 patients with an unknown status of extension and 29 patients with massive ETE. RESULTS: Of the 515 patients, 401 were found to have a METE. We analyzed the 464 patients who were without distant metastasis at the time of the initial diagnosis and who had a follow-up duration of more than 6 months. METE was not significantly associated with tumor recurrence during the follow-up period (median follow-up period: 122 months, range: 6-142 months): 8% vs. 15% of the patients with and without METE had tumor recurrence, respectively (P = 0.069 by the log-rank test). We analyzed the effect of tumor size in the patients with METE. Size was not significantly associated with tumor recurrence (P = 0.374 by the log-rank test). CONCLUSION: These findings suggest that METE might not be a prognostic factor to predict tumor recurrence in patients with PTC, including PTMC.