Thyroid carcinoma invading the cervicovisceral axis: Routes of invasion and clinical implications

Background. Controversy exists about the routes of invasion (extrathyroidal versus lymphogenic extension) when differentiated carcinoma (DTC) and medu llary thyroid carcinoma (MTC) invade the cervi-covisceral axis (ie, larynx, trachea, esophagus). Methods. We carried out an institutional analysis, from November 1994 to Oc tober 1999, of 451 consecutive patients undergoing surgery for DTC and MTC. Results. Irrespective of tumor entity, carcinomas with cervicovisceral inva sion (n = 34) were significantly larger and displayed higher pT categories (mainly pT4) than noninvasive carcinomas. In invasive papillary thyroid car cinoma (PTC) and MTC, the rates of positive lymph nodes were significantly higher than in noninvasive controls. When separate logistic regression anal yses were fitted for laryngeal, tracheal, and esophageal invasion, extrathy roidal growth (pT4) consistently was a significant factor predictive of inv asion in both DTC and MTC, with relative risks of 10.9 to 67.8. As the rout es of invasion are similar in DTC and MTC, all data were pooled for multiva riate analyses. Herein, the pN1 category had a significant impact only on e sophageal invasion, with a relative risk of 4.7. Conclusions. Invasion of the cervicovisceral axis is more often caused by e xtrathyroidal growth than by nodal metastasis. To keep nodal metastasis fro m encroaching onto the cervicovisceral axis, paratracheal and paraesophagea l lymph nodes should be cleared from the cervicocentral compartment at the primary operation.