The diagnostic accuracy of calcitonin levels in fine-needle aspirate (Ct-FNA) washout fluid is greater than that of cytology in medullary thyroid carcinoma (MTC), a new study published in the Turkish Journal Of Medical Sciences found. They would, therefore, be complementary to cytology results.
The researchers also demonstrated that the ratio of Ct-FNA over serum calcitonin was able to better predict lymph node metastasis in recurrent MTC than a particular cut-off for Ct-FNA alone.
The diagnostic value of Ct-FNA has been extensively studied in the case of thyroid nodules and lymph nodes but not much data are available for neck recurrences/metastases of MTC.
Here, a team of researchers led by Demet Çorapçıoğlu, MD, from the Department of Internal Medicine at Ankara University in Turkey retrospectively reviewed the database of patients with MTC from 2010 to 2021 to assess the diagnostic accuracy of Ct-FNA and cytology in detecting neck lymph node metastases of recurrent MTC cases.
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They identified 32 recurrent patients with MTC who had fine-needle aspirate and calcitonin measurements from washout samples during this time period and found that the median serum calcitonin level of the patients was 723 pg/mL and the median Ct-FNA washout fluid level was 1800 pg/mL.
The diagnostic accuracy of Ct-FNA washout fluid was 95.4% while that of cytology was 86%. When a cut-off level of more than 638.5 pg/mL was used, the Ct-FNA could predict the diagnosis of lymph node metastasis of recurrent MTC with a sensitivity of 80% and a specificity of 94.9%.
Similarly, if a cut-off level of more than 1.16 was used, the Ct-FNA/serum calcitonin ratio could predict the diagnosis of lymph node metastasis with a sensitivity of 92.3% and specificity of 100%.
“As Ct-FNA has greater diagnostic accuracy in our study, it would be complementary to cytology results to localize metastatic [lymph nodes] in recurrent MTC,” the authors concluded.
Gökçay Canpolat A, Şahin M, Ceyhan K, et al. Calcitonin levels in washout samples vs. cytology in the detection of malignant lymph node metastasis in recurrent medullary thyroid cancer. Turk J Med Sci. 2021;51(6):3061-3066. doi:10.3906/sag-2105-280