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Assessment of significance of proportions of intraductal and infiltrating tumor growth in ductal carcinoma of the breast

A series of 267 mammary carcinomas of intraductal or infiltrating duct type treated by mastectomy was divided by histologic examination into 6 groups: pure intraductal carcinoma (14 cases); intraductal carcinoma with less than 10% stromal infiltration (14 cases); predominantly intraductal carcinoma with 10‐49% stromal infiltration (16 cases); infiltrating duct carcinoma with a large component of intraductal growth (50‐89% infiltration—26 cases); infiltrating duct carcinoma with minimal intraductal growth (90‐99% infiltration—64 cases); and pure infiltrating duct carcinoma with no intraductal component (133 cases). There were no axillary nodal metastases and no tumor‐related deaths among the patients with pure intraductal carcinoma, but women whose tumors showed minimal (less than 10%) stromal infiltration had low but significant incidences of metastases and mortality. It appears from the present series and a review of the literature that women with pure intraductal carcinoma (which should be diagnosed only after multiple permanent sections) can safely be treated by less than radical mastectomy, and should have virtually normal life expectancies after treatment. In tumors with increasing proportions of infiltrating growth, there is a progressive increase both in nodal metastases and in mortality. Data are also presented which indicate that, unlike lobular carcinoma of the breast, ductal carcinoma has a very transitory pre‐infiltrating phase and may evolve by different mechanisms. Paget's disease of the nipple in this series was never associated with infiltrating carcinomas lacking an intraductal component, and occurred most frequently with predominantly intraductal tumors.