A contribution to the natural history of breast cancer. III. Changes in the basement membranes in breast cancers with stromal microinvasion.

Twenty-eight small breast cancers and 17 other breast cancer specimens from which appropriate semi-thin sections had been prepared were examined by electron microscopy and special staining techniques for alterations in the basement membranes and the basal lamina. In each case disruptions of the basement membranes were invariably observed at the point of initial invasion. Two types of invasion were noted: (1) bud-like protrusions of intraduct cancer with disruption of the basement membranes at the point of invasion; (2) extensive basement membrane defects with single cancer cell invasion. Our study confirms that invasive breast cancer originates in intraductal or lobular carcinoma in situ.