갑상선 미세유두암에서 갑상선 주변 조직 침윤(Minimal Extrathyroid Extension)의 임상적 의의

The Clinical Significance of Minimal Extrathyroid Extension in Patients with Papillary Thyroid Microcarcinoma

Purpose: The prognosis of papillary thyroid carcinoma is determined by such risk factors as old age, male gender, a large tumor size and extrathyroid extension. The aim of this study was to investigate the value of extrathyroid extension for the recurrence of papillary microcarcinoma and its association with the risk factors for papillary thyroid carcinoma. Methods: We retrospectively studied 167 patients with papillary microcarcinoma and who underwent thyroidectomy from Feb. 2003 to Dec. 2008. Papillary microcarcinoma (PTMC) was defined as a tumor smaller than 1 cm and an extrathyroid extension was identified by the pathological findings. Age, gender, extrathyroid extensions, the operative methods, lymph node metastasis and the MACIS score were analyzed by the appropriate statistical methods. Results: Patients with PTMC showed a lower MACIS score, fewer lymph node metastasis and less extrathyroid extension, as compared to the patients with papillary thyroid carcinoma. Total thyroidectomy and selective lymph node dissection were less frequently done in the patients suffering with PTMC. Analysis of the risk factors showed that PTMC had a close relationship with lymph node metastasis, the extent of surgery and multifocal cancer. The disease free survival rate of the patients with PTMC was statistically related with lymph node metastasis, but not with an extrathyroid extension (P=0.001). Conclusion: The patients with PTMC showed less lymph node metastasis and extrathyroid extension as compared to the patients with PTC. Lymph node metastasis of PTMC is an independent factor for disease free survival, but minimal extrathyroid extension is not related with recurrence. PTMC with lymph node metastasis should be regarded as an aggressive large tumor and lymph node dissection should be done. (Korean J Endocrine Surg 2008;8:243-249)