Predictive value of extent and grade of ductal carcinoma in situ in radiologically guided core biopsy for the status of margins in lumpectomy specimens.

AIMS: The correlation between the extent and grade of ductal carcinoma in situ (DCIS) in a core needle biopsy of breast, and the presence of an extensive intraductal carcinoma component (EIC) or positive resection margins in a subsequent mastectomy, has not been adequately addressed in the literature. MATERIALS AND METHODS: Seventy-eight core needle biopsies with mammography and mastectomy correlation (27 total mastectomies, 51 lumpectomies) were reviewed. The extent and grade of DCIS in the biopsies were determined and compared with the mammographic findings and the status of the EIC and margins in subsequent mastectomy specimens. RESULTS: Twenty-four cases of core biopsies with at least three foci of low-grade DCIS or at least two foci of high grade DCIS (group I) corresponded in large part to cases of mastectomy with a positive EIC (20/23 cases, or predictive value of 87%). Nine of 15 cases of lumpectomy in this group were associated with margins positive for or close to (less than 0.1 cm from) carcinoma. Thirty-three cases of core biopsies with one or two foci of low-grade DCIS or one focus of high-grade DCIS (group II) were associated with mastectomies with a limited extent of DCIS. Only four of 22 lumpectomy specimens in this group had margins positive for or close to carcinoma. Twenty-one cases of core biopsies without DCIS (group III) represented all five mastectomy specimens without DCIS, and 16 mastectomies with DCIS and negative EIC. None of the 14 cases of lumpectomy in this group had margins positive for carcinoma. The predictive value for EIC status may be even higher if mammographic findings are used in cases with a low number of foci (two foci of low-grade DCIS or one focus of high-grade DCIS in short biopsy cores). CONCLUSIONS: There was a good correlation between the extent and grade of DCIS in core biopsies and the status of EIC in subsequent mastectomy specimens. Core needle biopsies with at least three foci of low-grade DCIS or at least two foci of high-grade DCIS are associated with a greater likelihood of positive or close margins in subsequent lumpectomies. Core biopsies without DCIS are associated with a greater likelihood of negative margins in subsequent lumpectomies.