PHOENIX – In patients with recurrent papillary thyroid cancer, fine-needle aspiration cytology and thyroglobulin washout was a highly sensitive and specific means of detecting metastatic disease, according to a retrospective analysis.
Surgeon-performed FNA-Tg washout appears to increase the diagnostic accuracy in detecting metastatic disease in this patient population. Routine performance of the combined modalities should be considered in patients with suspicious metastatic lymphadenopathies, said Dr. Hossam Mohamed of the division of endocrine and oncological surgery in the department of surgery at Tulane University, New Orleans.
In a retrospective study of 117 patients with recurrent papillary thyroid cancer, the combination of surgeon-performed fine-needle aspiration cytology (FNAC) with fine-needle aspiration thyroglobulin washout (FNA-Tg) had a 100% specificity, 94.9% sensitivity, and negative predictive value of 93.75%, with a diagnostic accuracy of 97.1%, he said.
"Cervical lymph node involvement has been reported to be up to 46% at initial diagnosis, hence ultrasonography and fine-needle aspiration have been standard diagnostic modalities used to detect and evaluate cervical lymph nodes in patients with thyroid malignancies," he said at the annual Society of Surgical Oncology Cancer Symposium.
His team hypothesized that by adding surgeon-performed ultrasonography with Tg washout to FNAC for the management of patients with suspicious lymphadenopathies, they might be able to increase the accuracy of the combined tests for detecting metastatic disease in patients with recurrent papillary thyroid cancers.
In a retrospective study, they looked at results for patients who underwent preoperative FNAC and FNA-Tg washout followed by selective neck dissection. All dissections were performed by senior author Dr. Emad Kandil, chief of the endocrine surgery section at Tulane University.
They correlated the test results with the final pathology results of the dissected lymph nodes, and compared the sensitivity and specificity of the combined modalities to those of standard FNAC alone.
Of the 117 patients, 76% were female, and mean age was 52 years. Nearly half of the patients (47.6%) had cervical lymph node dissections, 39.7% had modified radical lymph node dissections, 6.35% had combined modified-radical, and 12.7% had combined modified-radical and cervical resections. Half of the group required second resections.
When the researchers compared the individual modalities to the final pathology results, they found that the respective sensitivity of FNAC, FNA-Tg, and the two combined were 84.6%, 89.4%, and 94.9%. They found the respective specificities to be 100%, 96.8%, and 100%.
The negative predictive value of FNAC was 87.1%. and of FNA-Tg was 85.7%. When the two diagnostic methods were used together, they ruled out metastases with 93.75% accuracy.
"Only one patient had a negative lymph node pathology with a positive FNA-Tg washout, which we couldn’t find an explanation for," Dr. Mohamed said.
Two patients who had negative FNA-Tg washout levels had evidence of atypical cells on FNAC and elevated serum Tg levels. These patients were therefore taken to surgery, and were found to have metastatic disease on final pathology, he said.
The study was internally funded. Dr. Mohamed reported having no financial disclosures.