Development and validation of a nomogram for preoperative prediction of level VII nodal spread in papillary thyroid...

To develop and validate a diagnostic nomogram for preoperative prediction of the level VII nodal spread in papillary thyroid cancer (PTC) by incorporating CT features.

A dataset of 7896 patients experiencing thyroidectomy for thyroid cancer was collected retrospectively from two hospitals, and 300 patients were finally included in this study. The CT features of metastatic LN were extracted with a one by one match of radiologic-pathologic correlation. Multivariable binary logistic regression analysis was used to develop predicting model, and then a nomogram was developed utilizing a primary cohort of 152 patients from hospital #1. The nomogram was validated in external cohort of 62 patients from hospital #2 and an independent cohort of 86 patients from hospital #1. The performance of the nomogram was evaluated with respect to its calibration, discrimination.

531 LNs from 300 patients were analyzed. 42.6% LNs were > 5 mm in short diameter. A total of 7 selected CT features were significantly associated with LN status (P < 0.05), including nodular enhancement, cystic change, calcification and so on. These features were contained in the prediction nomogram. The model showed good discrimination and good calibration, with a C-index of 0.938 (95% CI, 0.913 to 0.963) and 0. 795 (95% CI, 0. 726 to 0.864) for the primary cohort and the validation cohort, respectively. Decision curve analysis demonstrated that the nomogram was clinically applicable.

This nomogram incorporating pathologically relevant CT features has demonstrated a high diagnostic value for predicting level VII nodal spread in PTC. Our work may help thyroid surgeon to decide whether upper mediastinal lymphadenectomy should be performed, which is associated with thoracotomy or other surgery.