RESUMEN
One-hundred and eleven patients were studied with the objective of exploring the diagnostic usefulness of the fine needle aspiration (FNA) biopsy in cases with cancer of the thyroid gland. The mean age of the total sample was 42.4 years, with 89 percent females. A thyroid gland FNA was done in all cases as well as a surgical intervention for the establishment of a definitive diagnosis (i.e., gold standard). The cytologic diagnosis was done by the same expert pathologist in all cases. The diagnostic accuracy was obtained using a 2 x 2 table. Sensitivity was found to be 72 percent and specificity 91 percent, with 85.5 percent of diagnostic accuracy. Taking into account a 30 percent prevalence in our sample, predictive values were found to be 81 percent for positive and 87 percent for negative. It is concluded that FNA is better than the gold standard in the following points: it is easy to do, it has lower risk, and it has lower discomfort and financial cost. FNA showed a better utility to identify the absence of cancer. This is a procedure which is recommended for use in hospitals similar to the General Hospital of Mexico S.S. as part of the presurgical diagnosis in cases with clinical suspicion of thyroid gland malignancy.