Breast Cancer Type

The type of breast cancer is generally determined by the microscopic appearance of the tumor. When the pathologist examines the tissue, either from a needle core biopsy or surgical excision, they make a determination if the cells are ductal or lobular in origin, and whether or not invasion is present. There are times when it is difficult to tell exactly what type of cancer is present – breast cancers can have a variable appearance and the diagnosis is not always obvious by the initial microscopic appearance. A variety of special stains may be used, and these additional tests can confirm if a tumor is ductal or lobular (some cancers are “mixed” , having features of both cell types), of if invasion is present or not.

As a first approximation this is not really a concern. When chemotherapy (in general) is needed, the subtype of breast cancer does not have a reliable association with the benefits of individual drugs and regimens.