The association between tumor's location and cervical lymph nodes metastasis in papillary thyroid cancer.

ABSTRACT

BACKGROUND: Papillary thyroid cancer (PTC) has a strong propensity to metastasize to the cervical lymph nodes. Little was known currently about whether tumor's location would influence the risk of lymph node metastasis in PTC. METHODS: The study enrolled PTC patients who underwent primary surgical therapy in our center for small unifocal tumor. The tumor's location was evaluated by ultrasound in three axes, three planes and 3D space. Logistic univariate and multivariate analysis were applied to explore the association between tumors' location and the risk of lymph node metastasis in PTC. Different localization methods of thyroid tumors were evaluated using ROC curve. RESULTS: Totally 1,266 PTC patients were enrolled in this study. Univariate and multivariate analyses showed that gender, age, tumor size and tumor's location (in longitudinal axis, longitudinal sagittal plane, longitudinal coronal plane, sagittal coronal plane and 3D space) was associated with central lymph node dissection (CLND); gender, tumor size and tumor's location (in longitudinal axis, coronal axis, longitudinal sagittal plane, longitudinal coronal plane, sagittal coronal plane and 3D space) was related with lateral lymph node dissection (LLND) (P<0.05). In the ROC curve analysis, the 3D location showed the highest predictive value of lymph node metastasis (C-statistics 0.724 for CLNM; 0.763 for LLNM). The middle posterior lateral (OR=2.575, P=0.028), inferior anterior central (OR=2.829, P=0.016), inferior posterior lateral (OR=2.759, P=0.039) and isthmus tumors (OR=4.526, P=0.001) were at a higher risk of CLNM, and the middle anterior central tumors (OR=0.102, P=0.015) were related with lower risk of LLNM. CONCLUSIONS: Stereotactic localization showed the highest predictive value of lymph node metastasis. The middle posterior lateral, inferior anterior central, inferior posterior lateral and isthmus tumors were at a higher risk of CLNM when compared to other locations. For such patients, careful preoperative evaluation of nodal status should be done.