Fine-needle aspiration biopsy of thyroid nodules: impact on clinical practice.

Abstract

The aim of the present study was to analyze the changes in our clinical practice due to the use of FNAB in the management of nodular thyroid disease. Patients attended the thyroid unit for thyroid nodules. The study comprises three periods: First, from January 1980 to May 1984, 226 patient. Second, from June 1985 to December 1990, 166 patients. Third, from January 1991 to December 1993, 403 patients. retrospective the 1st period and prospective the 2nd and 3rd periods. During the 1st and 2nd periods, decision for surgery was based on clinical parameters together with results of 99Tc radionucleotide scan and B mode ultrasound studies. In the 3rd period surgical decision was based principally on cytologic results. We comparatively studied the frequency of surgical operation and frequency of malignancy in surgical thyroid specimens between the study periods. Determination of sensitivity, specificity and accuracy of the diagnostic methods was done. We observed a decrease in the frequency of patients requiring surgery, 89.9%, 67.8% and 46.6% for the 1st, 2nd and 3rd study periods, X2 = 114.7, p < 0.0001; and an increase in the frequency of malignancy in the surgical specimens, 14.7%, 24.4% and 32.9% for 1st, 2nd and 3rd periods respectively, X2 = 4.5, p < 0.05. The sensitivity 92.5% and 93.5%, the specificity 50.6% and 61.1%, and the accuracy 60.9% and 71.8% of the FNAB for the second and third periods respectively. The rates of false negative cytological specimens were 1.8% and 2.1% for 2nd and 3rd respectively, p > 0.05. Since the introduction of FNAB in the evaluation of our patients around 70% of these had a definitive preoperative diagnosis of either benign or malignant disease. Simplification in management of patients with nodular thyroid disease is the most important impact for the use of FNAB. Furthermore, a decrease in the number of patients requiring surgical treatment and an increase of malignant nodules in the specimens obtained by surgery were also observed. We think that FNAB is the most direct and accurate method in the management of patients with thyroid nodules.