Thyroglobulin in Washout Fluid From Lymph Node Fine-needle Aspiration Biopsy in Papillary Thyroid Cancer: Large-scale Validation of the Cutoff Value to Determine Malignancy and Evaluation of Discrepant Results

• Published in: The journal of clinical endocrinology and metabolism Vol. 98; no. 3; pp. 1061 - 1068
• Main Authors: Moon, Jae Hoon, Kim, Yong Il, Lim, Jung Ah, Choi, Hoon Sung, Cho, Sun Wook, Kim, Kyung Won, Park, Hyo Jin, Paeng, Jin Chul, Park, Young Joo, Yi, Ka Hee, Park, Do Joon, Kim, Sang Eun, Chung, June-Key
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01.03.2013; Copyright by The Endocrine Society
• Subjects: Adult; Aged; Biological and medical sciences; Biopsy, Fine-Needle - methods; Biopsy, Fine-Needle - standards; Body Fluids - metabolism; Carcinoma - metabolism; Carcinoma - pathology; Carcinoma, Papillary; Diagnosis, Differential; Endocrinopathies; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; Lymph Nodes - metabolism; Lymph Nodes - pathology; Male; Medical sciences; Middle Aged; Predictive Value of Tests; Reference Values; Reproducibility of Results; Retrospective Studies; ROC Curve; Sensitivity and Specificity; Thyroglobulin - metabolism; Thyroid Cancer, Papillary; Thyroid Neoplasms - metabolism; Thyroid Neoplasms - pathology; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Evaluation; Obesity; Statistical analysis; Papillary carcinoma; Lymph node; Nutrition; Nutrition disorder; Metabolic diseases; Malignancy; Malignant tumor; Aspiration punction; Result; Test validation; Thyroglobulin; Biopsy; Thyroid hormone; Endocrinology; Nutritional status; Cancer
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2012-3291

Context: There are still some controversies regarding the cutoff value and the influential factors of thyroglobulin (Tg) concentration in washout fluid from fine-needle aspiration (FNA) biopsy (FNA-Tg) on cervical lymph nodes (LNs) in patients with papillary thyroid cancer (PTC). Objective: Our aims were to validate the cutoff value of FNA-Tg in diagnosing malignant LNs on a large scale and to investigate the influential factors that could result in the discrepancy between the final diagnosis and FNA-Tg. Design, Setting, and Participants: We conducted a retrospective cohort study based on hospital records with 528 cases of FNA-Tg measurement from 419 PTC patients. Main Outcome Measure: The cutoff value of FNA-Tg was obtained from receiver operating characteristic analysis with final diagnosis. Binary logistic regression analysis was performed to investigate the influential factors. Results: In the final diagnosis, 190 LNs were malignant, and 338 LNs were benign. The median FNA-Tg was 521.2 (3676.8) ng/mL in malignant LNs, and 0.1 (0.2) ng/mL in benign LNs. The optimal cutoff value of FNA-Tg in distinguishing malignant LNs from benign LNs was 1.0 ng/mL (sensitivity, 93.2%; specificity, 95.9%) in all cases. Combining FNA-Tg and FNA cytology showed superior diagnostic power (sensitivity, 98.4%; specificity, 94.4%) when compared with diagnostic strategy using either FNA cytology or FNA-Tg alone. FNA-Tg, serum TSH, and serum Tg were higher in nonthyroidectomized patients than in thyroidectomized patients (P < .001, respectively). FNA-Tg was correlated with serum TSH and Tg levels (P < .001, respectively), and binary logistic regression analysis showed that serum TSH suppression and serum Tg presence independently affected the diagnosis made by FNA-Tg. Conclusions: Our results validated 1.0 ng/mL of FNA-Tg as a cutoff value for diagnosing LN metastasis of PTC and suggested that serum TSH suppression and serum Tg presence should be considered in diagnosing LN malignancy with FNA-Tg in PTC patients.