A novel definition of extrathyroidal invasion for patients with papillary thyroid carcinoma

Abstract

Although extrathyroidal invasion is one of the most significant risk factors for patients with papillary thyroid carcinoma (PTC), minimal, superficial adhesion does not affect their prognosis. The General Rules for the Description of Thyroid Cancer by the Japanese Society of Thyroid Surgery classifies minimal extrathyroidal invasion as Ex1, and massive invasion as Ex2. However, this definition is sometimes inconsistent between institutions or surgeons. We have defined only patients who had preoperative palsy of the recurrent laryngeal nerve, or patients with invasion of the mucosa of the trachea or esophagus as Ex3. When we can shave tumors off the laryngotracheal structures, the esophagus, or the recurrent laryngeal nerve, the condition is considered to be Ex2. From 1993 to 2004, among 562 patients with primary PTC (microcarcinomas were excluded), there were 272 patients with Ex0, 149 with Ex1, 81 with Ex2, and 60 with Ex3. Their 10-year disease-free survivals were 94%, 81%, 56% and 41%, respectively. There was a statistically significant difference between Ex1 and Ex2. However, as for 10-year disease-specific survivals which were 99%, 94%, 91% and 65%, respectively, a significant difference existed between Ex2 and Ex3. In conclusion, this novel definition of extrathyroidal invasion for patients with PTC leaves no room for confusion and is valuable in predicting their prognosis. © 2006, Japan Society for Head and Neck Cancer. All rights reserved.