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Thyroglobulin measurement in fine‐needle aspirate washouts: the criteria for neck node dissection for patients with thyroid cancer
Author(s) -
Kim Min Jung,
Kim EunKyung,
Kim Byung Moon,
Kwak Jin Young,
Lee Eun Jig,
Park Cheong Soo,
Cheong Woong Youn,
Nam Ki Hyun
Publication year - 2009
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2008.03297.x
Subject(s) - medicine , thyroglobulin , fine needle aspiration , lymph node , thyroid cancer , biopsy , papillary thyroid cancer , cytology , thyroid , neck dissection , radiology , nuclear medicine , cancer , pathology
Summary Background Several studies report that detection of thyroglobulin (Tg) in fine‐needle aspiration (FNA) biopsy washout fluid from lymph nodes identifies recurrences/metastases of differentiated papillary thyroid cancer (DPTC) in the neck with higher sensitivity and specificity than fine‐needle aspiration cytology (FNAC). However, the diagnostic FNA‐Tg cutoff values have not yet been established. Objective To determine an appropriate diagnostic threshold value for Tg levels in FNA washout fluid in patients with neck node metastases or recurrences of DPTC. Design We performed ultrasound (US)‐guided FNAC and measured Tg levels in FNA washout fluid (FNA‐Tg). Final diagnoses were confirmed by histological examination of excised specimens or by follow‐up examinations for at least 24 months. Patients A total of 168 ultrasonographically detected lymph nodes from 168 patients with DPTC were included. Measurements In comparison with FNAC, we evaluated diagnostic sensitivity, specificity and accuracy of metastasis detection according to several predetermined threshold levels: 1, 10, 100 ng/ml, mean+2SD of node‐negative patients, and FNA‐Tg/serum‐Tg > 1. Results The diagnostic sensitivity was lowest at 77·3% for FNAC alone. The lower FNA‐Tg threshold levels showed higher diagnostic sensitivity whereas the higher FNA‐Tg showed higher specificity. In addition to the FNAC results, FNA‐Tg levels showed 95·0% sensitivity, 81·6% specificity, 92·6% in positive predictive value (PPV) and 87·0% in negative predictive value (NPV) with the threshold of FNA‐Tg level at 10 ng/ml, serum‐Tg or mean+2SD of FNA‐Tg measured in node‐negative patients. The diagnostic accuracy of FNA‐Tg was higher in neck node recurrences after thyroid surgery than in the metastasis of patients waiting for surgery. Conclusion FNA‐Tg measurement as well as FNAC should be performed either before or after surgery to evaluate neck node metastases or recurrences in patients with differentiated thyroid carcinomas. We recommend that the threshold values for FNA‐Tg levels should be > 10 ng/ml if the serum‐Tg level or the mean+2SD in node‐negative patients is not available for reference.