In situ cancer and Invasive cancer
In situ cancers. These types haven't spread past the duct or lobule where they started.
Ductal carcinoma in situ (DCIS). This is ductal carcinoma in its earliest stage (stage . In this case, the disease is still in the milk ducts. But if you don’t treat this type, it can become invasive. It’s often curable.
Lobular carcinoma in situ (LCIS). This is found only in the lobules, which produce breast milk. It isn't true cancer, but it means you’re more likely to get breast cancer later. If you have it, get regular breast exams and mammograms.
Invasive cancers. These have spread or invaded the surrounding breast tissue.
Invasive or infiltrating ductal carcinoma (IDC). This cancer starts in the milk ducts. It breaks through the wall of the duct and invades the fatty tissue of the breast. It’s the most common form, accounting for 80% of invasive cases.
Invasive lobular carcinoma (ILC). This cancer starts in the lobules but spreads to surrounding tissues or other body parts. It accounts for about 10% of invasive breast cancers. Subtypes of this invasive breast cancer include:
Adenoid cystic (or adenocystic) carcinoma. These are similar to cells found in your salivary glands and saliva.
Low-grade adenosquamous carcinoma (a type of metaplastic carcinoma). This rare tumor is usually slow-growing and often mistaken for other types.
Medullary carcinoma. The tumors in this rare type are a soft, squishy mass that looks like part of your brain called the medulla.
Mucinous carcinoma. Tumors in this rare type float in a pool of mucin, part of the slippery, slimy stuff that makes up mucus.
Papillary carcinoma. Fingerlike projections set these tumors apart. This rare type usually affects women who’ve been through menopause.
Tubular carcinoma. The tumors are slow-growing and tube-shaped.