Breast Cancer Types

Many people might not realize how many types of breast cancer there are until their own breast cancer diagnosis. And, for some patients, it’s important to know and understand the various types of breast cancer so they can feel well prepared going into their treatment journey. You can use this guide to learn more about breast cancer types, how they are determined, and how they are classified.

After a breast cancer diagnosis, your medical team will need to determine many things about your breast cancer. They will use a preliminary pathology report, that is received after your biopsy, to gather this important information, such as the stage of the disease, hormone receptor status, and the specific type of breast cancer you have in order to begin organizing your breast cancer treatment plan. To do this, an in-depth evaluation will be done on the tissue sample collected from your breast biopsy, or on the tumor itself after your breast cancer surgery. There are several factors that are looked at including:

  1. Origin point of the cancer cells
  2. How the breast cancer cells look under the microscope
  3. How the cancer cells react to hormones
  4. The breast cancer cells’ genetic makeup

Breast Cancer Types

Breast cancer occurs in two broad categories, based upon their their relationship to the walls of their origin: invasive and noninvasive.

  • Invasive (infiltrating) means that the cancer has spread to surrounding tissues.
  • Noninvasive (in situ) means that the cancerous cells are still confined to their point of origin.

Sometimes, there can be a combination of different cancer types within a single breast tumor. In some cases, where the breast cancer type is very rare, a lump or tumor may never form at all - such as inflammatory breast cancer.

Common Categories of Breast Cancer

There are certain breast cancers that are more common than others. Some specific types of common breast cancer include:

Ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer where abnormal cells have been contained in the lining of the breast milk duct. Sometimes referred to as intraductal. DCIS isn’t considered life-threatening, but it can increase the risk of developing an invasive breast cancer later on. Most recurrences happen within 5-10 years after initial diagnosis.

Lobular carcinoma in situ

Lobular carcinoma in situ (LCIS) is also sometimes called lobular neoplasia or intralobular. Though the name can be confusing, LCIS is actually not considered a cancer or a pre-cancer because it doesn’t turn into invasive cancer if untreated. Rather, LCIS is an indication that a person is at a higher risk of getting breast cancer later on.

Invasive ductal carcinoma

Invasive ductal carcinoma or infiltrating ductal carcinoma (IDC) means that abnormal cells that originated in the lining of the breast milk duct have invaded surrounding tissue. Over time, IDC can spread to the lymph nodes and possibly to other areas of the body. Invasive ductal carcinoma is the most common type of breast cancer, accounting for approximately 80% of all breast cancers.

Invasive lobular carcinoma

Invasive lobular carcinoma (ILC) starts in the milk-producing glands (lobules) and can spread to other parts of the body. Invasive lobular carcinoma is the second most common form of invasive breast cancer, accounting for 10 to 15% of breast cancer cases.

Invasive breast cancers, like invasive ductal carcinoma and invasive lobular carcinoma, will most likely require an oncology team to create a treatment plan using one or more of the following:

Less Common Types of Breast Cancer

Inflammatory breast cancer

A less common type of breast cancer, accounting for 1-3% of all breast cancers is Inflammatory breast cancer (IBC). IBC often appears to be an infection (breast red, swollen and inflamed) but it is actually cancer that is blocking lymphatic vessels in the skin and breast tissue, causing a buildup of fluid (lymph).

Paget’s disease of the nipple

This type of breast cancer starts in the breast ducts and spreads to the skin of the nipple and then to the areola, the dark circle around the nipple. Paget’s disease can be either intraductal or invasive. Together, this type of breast cancer only accounts for about 1% of all cases of breast cancer.

Phyllodes tumor

Phyllodes tumors are rare breast tumors. These tumors develop in the connective tissue (stroma) of the breast and grow in a leaflike pattern. Although phyllodes tumors tend to grow quickly, they rarely spread outside the breast.

Angiosarcoma

Angiosarcoma is a cancer in the inner lining of blood vessels that can occur in any part of the body. This form of cancer rarely occurs in the breast.

Medullary Carcinoma

A rare breast cancer that accounts for less than 5% of all breast cancers case, it is a subtype of invasive ductal carcinoma. It is named for it’s soft, fleshy resemblance to the brain’s medulla. It doesn’t normally grow quickly or spread into the lymph nodes.

Mucinous Carcinoma

Mucinous carcinoma, also known as colloid carcinoma, is rare form of invasive ductal carcinoma where the tumor is made up of abnormal cells found in pools of mucin. Mucin is found in mucus, which lines our bodies digestive tracts, liver, lungs, and other organs. In mucinous carcinoma, however, mucin becomes part of the tumor and surrounds the breast cancer cells. Under a microscope, it looks like the cancer cells are scattered throughout pools of mucus.

Tubular Carcinoma

Tubular carcinomas are usually small (about 1 cm or less) and made up of tube-shaped structures called "tubules." These tumors tend to be low-grade, meaning that their cells look somewhat similar to normal, healthy cells and tend to grow slowly. It is a subtype of invasive ductal carcinoma.

Cribriform Carcinoma

In invasive cribriform carcinoma, the cancer cells invade the connective tissues of the breast in nest-like formations between the ducts and lobules. Within the tumor, there are distinctive holes in between the cancer cells, making it look something like Swiss cheese. Invasive cribriform carcinoma is usually low grade, meaning that its cells look and behave somewhat like normal, healthy breast cells.

Papillary Carcinoma

A very rare form of breast cancer, Invasive papillary carcinomas usually has a well-defined border and is made up of small, finger-like projections. If the cells are very small they are called micropapillary. In most cases, these types of tumors are diagnosed in older, postmenopausal women. In most cases of invasive papillary carcinoma, DCIS is also present.