Ductal carcinoma of the breast. An analysis of proportions of intraductal and invasive components.

One hundred and ninety patients with mammary ductal carcinoma were studied to evaluate the correlation of proportions of intraductal and invasive tumor growth to histologic and immunohistochemical features. Initially, attempts were made to divide the cases into 6 groups according to the proportion of extraductal invasive areas within the whole tumor. It has been found that ductal carcinoma could be divided, on this criterion, into 2 groups. One comprised tumors in which invasive areas made up less than 20% of the tumor, the other included those with invasive areas exceeding 20%. In the former, intraductal and invasive components exhibited a lower grade of nuclear and tumor component and a higher incidence of cells with CEA immune positivity. The latter manifested higher grades in both intraductal and invasive components and a lower incidence of CEA positive cells. Many of the latter tumors had a solid or comedo-like growing pattern of the intraductal component. There was a significant difference in the prognosis between the two categories. We conclude that like intraductal carcinomas, invasive ductal carcinomas with a predominant intraductal component should be considered a lower grade malignancy.