The incidence of positive margins with breast conserving therapy following mammotome biopsy for microcalcification

BACKGROUND AND OBJECTIVES: The ability to achieve clean margins with breast conserving therapy varies greatly even when the diagnosis of carcinoma is known beforehand. Although several reports reveal that the incidence of positive margins decreases after stereotaxic core biopsy of nonpalpable lesions and fine-needle aspiration biopsy of palpable lesions, the data on the results following mammotome biopsy (mmbx) is scanty. METHODS: Two hundred and ninety-eight biopsy specimens for mammographically indeterminate microcalcification from 1/97 through 3/30/98 were reviewed. Biopsies were performed using the biopsys method utilizing an 11-gauge multidirectional, vacuum-directed device. RESULTS: Ten percent (n = 31) of the mammotome biopsies were atypical and 9% (n = 27) were malignant. These 58 cases (19%) were recommended for surgical excision. The incidence of positive margins in this subset was determined. Of patients who underwent lumpectomy as their initial surgical procedure 69% had negative surgical margins. Seventy-seven percent of patients with carcinoma diagnosed by mammotome biopsy had definitive initial surgery with a single surgical procedure. CONCLUSIONS: Mmbx facilitates fewer surgical procedures to achieve negative margins, and thus provides a better cosmetic result.