Don't forget Breast cancer infultrating duct enter your last name. You will be able to find the Grade of your tumor on your pathology report. Microcalcifications will often continue to form as a tumor develops and spreads. This type of cancer is rare and accounts for only 3 to 5 percent of breast cancers. Invasive ductal carcinoma IDC begins in the milk ducts and spreads to the fatty tissue of the breast outside the duct.