Determination of false negative rate in fine-needle aspiration of prostate. Study of sequential aspirations in 30 untreated carcinoma patients.

Despite several studies comparing the diagnostic accuracy of core needle biopsy and fine-needle aspiration (FNA) in the diagnosis of prostatic adenocarcinoma, no clear picture of the false negative rate for FNA is available. We studied 101 follow-up FNA evaluations in 30 patients with untreated well-differentiated carcinoma. The patients were followed for a median of two years and seven months and had from two to seven FNA follow-up evaluations (median = 2.5 evaluations per patient). If three inadequate evaluations are omitted, the combined rate of positive plus suspicious FNA biopsies was 92.9 percent (88.8% plus 4.1%, respectively). The residual false negative rate was 7.1 percent. The clinical features and follow-up data are described. A semiquantitative definition of "suspicious for malignancy" is suggested. We conclude that in experienced hands. FNA is a highly efficacious method for the diagnosis of prostatic adenocarcinoma.