Diagnostic utilities of washout CYFRA 21-1 combined with washout thyroglobulin for metastatic lymph nodes in thyroid cancer: a prospective study

Cervical lymph node (LN) metastasis is common in differentiated thyroid cancer (DTC). This study evaluated the utility of the washout CYFRA 21-1 level, combined with the thyroglobulin (Tg) concentration, in terms of diagnosis of LN metastasis. We prospectively enrolled 53 patients who underwent thyroid surgery to treat DTC with lateral cervical LN metastases. Preoperative ultrasound guided needle localization was used to surgical sampling of specific LNs during the operation. The intraoperative washout Tg and CYFRA 21-1 levels were measured in such LNs. The Tg and CYFRA 21-1 levels differed significantly between metastatic and benign LNs. The cutoff values were 2.63 ng/mL for washout CYFRA 21-1 and 22.62 ng/mL for Tg. Combined use of the washout Tg and CYFRA 21-1 levels afforded the highest diagnostic accuracy (92.5%), better than that of individual markers. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) were 94.6%, 90.0%, 91.4%, 93.8%, respectively. The conjunction of the washout CYFRA21-1 and Tg levels enhances the diagnostic accuracy of LN metastasis in DTC patients. The washout CYFRA 21-1 level may be useful when malignancy is suspected, especially in cases where the cytology and washout Tg findings do not provide definitive results.