Three- to six-year followup for 379 benign image-guided large-core needle biopsies of nonpalpable breast abnormalities.

Background: Determining the negative predictive value of benign large-core needle biopsy of nonpalpable mammographically detected breast abnormalities has been difficult because benign results generally preclude surgical excision. Longterm followup of these patients is important to ensure timely diagnosis of new abnormalities and to identify false negatives.

Study Design: This cohort study comprised 379 patients, all with benign diagnoses following imaging-guided large-core needle biopsy of nonpalpable mammographically detected abnormalities. Mammographic, clinical, and laboratory records (when appropriate) were reviewed for all patients followed at our institution. For patients followed elsewhere, these data were provided by each patient's current primary-care physician after obtaining written informed consent from the patient.

Results: We obtained followup for 312 patients (82.3% of 379), for whom the mean followup period was 55 months; 67 patients were either lost to followup (44, 11.6%), had no followup by patient choice (18, 4.7%), or died of causes other than breast cancer (5, 1.3%). Of these 312 patients, we found only 1 (0.3%) false negative in which a 4-mm lesion was observed to have grown to approximately 11 mm eight months later, and was found to be an infiltrating ductal cancer at rebiopsy. The negative predictive value was calculated as 0.997 (311/312). Analysis of core histologies indicated the followup group was a representative sample.

Conclusions: These data suggest that benign mammographically detected abnormalities can be diagnosed with a high level of confidence using image-guided large-core needle biopsy, and that mammographic or ultrasonographic screening or both at 6 and 12 months might be sufficient before returning the patient to routine screening mammography.