What is the role of cytopathologists in stereotaxic needle biopsy diagnosis of nonpalpable mammographic abnormalities?

The popularity of screening mammography has led to increased detection of mammographic lesions that require pathologic diagnosis. Stereotaxic needle biopsy techniques to sample such lesions can be used to either identify those lesions that require excision from those that can be followed, or to confirm a mammographic impression of malignancy prior to excision. Stereotaxic core biopsy (SCBX) and stereotaxic fine needle aspiration (SFNA) have rarely been directly compared. For this review we undertook a uniform re-analysis of the data that was presented in the published studies of SFNA and/or SCBX. The main endpoint was the negative predictive value (NPV) that measures the frequency that a benign diagnosis is truly benign. There was variability in NPV (likely due to sampling methods) and specific aspects of sampling techniques are discussed. The NPV was compared to indicators of selection of lesions to biopsy (frequency of invasive cancer in the study population), mammographic characteristics (masses or microcalcifications), and the reported nondiagnostic rates. The general conclusion is that SFNA and SCBX are equivalent in accuracy, with considerable variability that reflects the types of lesions that are selected for biopsy and the thoroughness of sampling. For SFNA studies, nondiagnostic rates were inversely related to NPV, and therefore have clinical implications. This was not shown for SCBX studies, and probably reflects an inability to correctly identify non-representative tissue biopsies. The main advantage for including cytologic methods with stereotaxic breast biopsy is immediate sample assessment, and this advantage can also be applied to core needle procedures.