Evaluation of stereotactic core needle biopsy (SCNB) of the breast at a single institution

Stereotactic core needle biopsy (SCNB) has become a popular method for diagnosis of occult breast abnormalities. There are few large series of SCNB from a single institution. Data on patients undergoing SCNB for mammographic abnormalities were collected prospectively over 43 months at a university hospital. Mammographic findings were categorized as benign, probably benign, indeterminate, suspicious or malignant. For lesions with SCNB pathology that were non-diagnostic, showed atypical hyperplasia or malignancy (in situ or invasive), or were discordant with the pre-biopsy mammogram findings, surgical excision was recommended. Subsequent surgical pathology was reviewed. All remaining lesions were followed mammographically after SCNB. SCNB was performed on 692 lesions in 607 patients. There were 79 malignancies, for a positive SCNB rate of 11.4%. The 349 SCNB performed for benign, probably benign and indeterminate lesions on mammography had a positive SCNB rate of only 4%. Surgery was recommended for 127 (18.3%) lesions, while 565 (81.6%) were followed mammographically after SCNB. A compliance rate of 61 % for at least one follow-up mammogram was obtained, with a median follow-up of 17.2 months and with no cancers found. The sensitivity for malignancy with SCNB was 93%. SCNB provides a minimally invasive method to assess mammographic abnormalities. Abnormalities considered radiographically to be other than malignant or suspicious yielded few cancers. In this series a low positive SCNB rate resulted in no false negatives on mammographic follow-up. The optimal positive biopsy rate for SCNB is debatable.