Relationship between grade of intraductal component of breast cancer within main tumor and extent of intraductal spread in surrounding tissue.

Ninety-three specimens obtained by quadrantectomy of invasive ductal carcinoma of the breast were examined to evaluate the correlation between the grade of the intraductal component within the tumor and the extent of intraductal spread in the surrounding tissue. We used immunohistochemistry of a-smooth muscle actin to visualize the contour of intraductal components. The grade of the intraductal component within the tumor was classified into 4 groups (td0 to td3) by counting number of intraductal components; the extent of intraductal spread in the surrounding tissue was also divided into 4 groups (sd0 to sd3) according distance from the tumor margin. Eifty-eight (89.2%) of 65 cases with low-grade td were low-grade sd, and 17 (60.7%) cases of high-grade td were high-grade of sd. The grade of the intraductal component correlated with the extent of intraductal spread in the surrounding tissue, significantly (p<0.001, Spearman rank correlation test). From these results, we belive that investigation of intraductal components within the tumor is useful for estimating the extent of intraductal spread in the surrounding tissue, and excision specimens from diagnostic lumpectomy should be examined for the extent of the intraductal component, the results being important in estimating the risk of local recurrence.