Clinical Implication of Cancer Adhesion in Papillary Thyroid Carcinoma: Clinicopathologic Characteristics and Prognosis Analyzed with Degree of Extrathyroidal Extension

Abstract

Macroscopic extrathyroidal extension (ETE) is a poor prognostic factor in papillary thyroid carcinoma (PTC). However, intraoperative inspection for ETE is often inaccurate and could lead the surgeon to misconstrue simple adhesion as gross ETE. Such confusion could result in more aggressive treatment than necessary. In the present study we investigated the frequency and clinical implication of simple adhesions. We identified 858 patients who underwent total thyroidectomy for papillary thyroid carcinoma (PTC). Clinicopathologic features, prognosis, and stimulated serum thyroglobulin (Tg) levels were compared between four groups divided according to degree of ETE: no ETE (n = 335), simple adhesion (n = 16), microscopic ETE (n = 378), and macroscopic ETE (n = 129). In the total of 145 cases, which were recognized as gross ETE under intraoperative inspection, 16 cases (11.0 %) were diagnosed as cancer confined to the thyroid without ETE by definite histology. The simple adhesion group showed no statistical differences in postoperative stimulated Tg levels from the no ETE and microscopic ETE groups (p > 0.05). In contrast, the distribution of postoperative Tg levels in the macroscopic ETE group was significantly higher than in the other groups (p < 0.001). During the 54-month median follow-up period, the macroscopic ETE and microscopic ETE groups showed poorer relapse-free survival than the no ETE and simple adhesion groups (p < 0.05). The findings of the present study indicate that the discrepancy between intraoperative inspection and definite histology is not negligible when dense adhesions are present. When no tumor is found, the patient with inflammatory or fibrotic adhesions has a favorable prognosis.