Washout CYFRA 21-1: A tool to improve diagnostic accuracy of fine needle aspiration in the diagnosis of metastatic lymph nodes in papillary thyroid cancer.

Thyroid carcinoma has an increasing incidence of endocrine system cancers. Fine needle aspiration cytology (FNAC) and thyroglobulin (Tg) are the primary diagnostic modalities employed for assessing metastatic lymph nodes (LNs) in thyroid cancer. Due to the limited accuracy, rare patients benefited from these procedures. In this research, we aimed to discover a dependable biomarker that could increase the accuracy of FNAC's ability to diagnose metastatic LNs among patients suffering from papillary thyroid cancer (PTC). From March 2021 to July 2023, 99 LNs from PTC patients who had thyroid ultrasonography suspicions of metastases were examined. All patients underwent FNAC, washout Tg and CYFRA 21-1 measurements. Surgical histology and a subsequent FNAC were utilized to validate the outcomes of LNs. In our study, the optimal cut-off value for CYFRA 21-1 washout fluid was 1.145 ng/mL, with a specificity of 94.00 % (slightly lower than Tg and FNAC at 98 %). However, CYFRA 21-1 demonstrated significantly higher diagnostic sensitivity (85.71 %) and accuracy (86.41 %) compared to Tg (71.43 %, 81.55 %) and FNAC (69.39 %, 80.58 %). Furthermore, FNAC plus washout CYFRA 21-1 performed better in diagnosing the metastatic LNs in PTC than FNAC plus Tg, which may indicate a novel solution for metastatic LNs diagnosis in PTC.