The Clinical Significance of a Minimal Extra-thyroidal Extension of Papillary Thyroid Cancer for the Recurrence of Regional Cervical Lymph Nodes

Hwang, Seong Bae; Ryu, Woo Sang; Seo, U Hyoung; Lee, Jea Bok; Bae, Jung Won; Koo, Bum Hwan

Abstract

PURPOSE: Extra-thyroidal extension has been recognized as a poor prognostic factor for increased regional recurrence risk in papillary thyroid carcinoma, and is known to require treatment that is more aggressive. In the recent UICC TNM 6th Classification, an extra-thyroidal extension was divided into a minimal extra-thyroidal extension (T3) and a massive extra-thyroidal extension (T4). The aim of this study was to investigate the clinical effect of a minimal extra-thyroidal extension of a papillary carcinoma for the recurrence of regional cervical lymph nodes.
METHODS
We retrospectively studied 154 patients with papillary thyroid carcinoma where a thyroidectomy was performed from Feb. 2003 to May. 2006 at the Department of Surgery, with the exclusion of 6 patients with a massive extra-thyroidal extension. We divided the cases into a no extra-thyroidal extension group and a minimal extra-thyroidal extension group according to the grading of the extra-thyroidal extension. The grading of the extra-thyroidal extension was based on both pathological findings and intraoperative surgical findings. Clinicopathological factors associated with each group were analyzed by univariate and multivariate analysis. We divided the cases into two groups according to age (<45 yrs, > or =45 yrs) and lymph node status (positive, negative), and compared each group with regards to disease free survival according to the grading of the extra-thyroidal extension.
RESULTS
By univariate analysis, a minimal extra-thyroidal extension was related to lymph node metastasis, tumor size, mutifocality (P<0.05), and was not related to cervical lymph node recurrence statistically (P=0.108). Cervical lymph node recurrence was related to being male, lymph node metastasis and tumor size (P<0.05). By multivariate analysis, a minimal extra-thyroidal extension was independently related to tumor size, multifocality, and lymph node metastasis (P<0.05). In both groups with regards to age and lymph node status, a minimal extra-thyroidal extension was not statistically related to disease free survival (P>0.05).
CONCLUSION
We need to downstage to less than T3 for a minimal extra-thyroidal extension because there is no significant difference in disease free survival according to the grading of an extra-thyroidal extension in patients with papillary thyroid carcinoma.