Abstract

On the basis of direction of the tumor extension, we divided the 68 advanced thyroid cancers with extracapsular spread into five types. Medial type was the most frequently seen in 35% of all differentiated thyroid cancers. The sites of extracapsular spread in medial type as follows : recurrent nerve was the most frequently invaded in 30%, trachea 16%, cervical esophagus 14%, larynx 5% and hypopharynx 1%. The majority of tumors invaded recurrent nerve, trachea or cervical esophagus arised from the primary tumors. With regard to the depth of tracheal invasion, in 68% of the patients with tracheal invasion, the tumor invaded within the tracheal wall, not beyond the tracheal mucosa. On the other hand, in all patients with eso phageal invasion, the tumor invaded within the muscle layers, not beyond the esophageal mucosa. Lateral type, inferior and anterior was seen in 10%, 2.5% and 19%, respectively. Therefore, in anterior type strap muscles should be resected with tumors as necessary. Radical neck dissection is indicated in patients whose metastatic inferior internal jugular node is more than 4cm in size, considering extracapsular invasion. The incidence of paratra cheal nodal metastasis was the most frequent (42.1%). It should be taken into account that a great tendency to extracapsular spread into recurrent nerve or trachea in a case of metastatic paratracheal node more than 2cm in size. Extracapsular spread was found more common in older men and in 91% of poorly differentiated thyroid cancers.