Significance of linear extent of breast carcinoma at surgical margin.

Background: Our objective was to correlate the extent of margin positivity and the findings on re-excision specimens of infiltrating mammary carcinoma.

Methods: We selected 50 consecutive cases of infiltrating mammary carcinoma, including both infiltrating ductal carcinoma and infiltrating lobular carcinoma, with positive margins followed by re-excision. Margin positivity was defined as the presence of cancer at the inked margin. The extent of margin positivity was assessed by measuring the linear involvement of the inked margin by the carcinoma.

Results: Twenty-one of 50 cases (42%) showed positive findings on re-excision, including either infiltrating carcinoma or carcinoma in situ or both. Nine of 14 cases (64%) with ductal carcinoma in situ or infiltrating ductal carcinoma on re-excision and 4 of 7 cases (57%) with lobular carcinoma in situ or infiltrating lobular carcinoma on re-excision had initial linear margins >1.0 cm, whereas 28 of 29 cases (96%) with negative findings on re-excision had initial linear margins <1.0 cm.

Conclusions: Linear measurement of the inked margin involved by infiltrating mammary carcinoma can be used as a predictor of findings on re-excisions.