Breast cancer is not a single disease, but rather a collective of a number of different types of the disease. Because of this, your specific cancer type will influence the type of breast cancer treatment you receive. To have a better understanding about what’s in store, 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 the specific type of breast cancer you have so you can begin treatment as soon as possible. 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 when determining breast cancer type including:
Origin point of the cancer cells
How the breast cancer cells look under the microscope
Whether the breast cancer cells react to hormones
The genetic makeup of the cancer cells
Breast cancer occurs in two broad categories:
Invasive (infiltrating), which means that the cancer has spread to surrounding tissues
Noninvasive (in situ), which 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.
There are certain breast cancers that are more common than others. Some common types of 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. Although not considered life-threatening, DCIS can increase the risk of developing an invasive breast cancer later on, with most recurrences happening within 5-10 years after initial diagnosis.
Invasive ductal carcinoma
Invasive 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. IDC accounts for approximately 80% of all breast cancers, making it the most common type of breast cancer.
Invasive lobular carcinoma
Invasive lobular carcinoma (ILC) starts in the milk-producing glands (lobules) and can spread to other parts of the body. It is the second most common form of invasive breast cancer, accounting for 10 to 15% of breast cancer cases.
Lobular carcinoma in situ
Lobular carcinoma in situ (LCIS), also sometimes called lobular neoplasia, is actually not considered a cancer or a pre-cancer. This is because LCIS doesn’t turn into invasive cancer if untreated. Rather, it is an indication that a person is at a higher risk of getting breast cancer in the future.
Although the breast cancers listed above are the most common, there are some rarer breast cancers that are still worth knowing more about, which include:
Inflammatory breast cancer
Inflammatory breast cancer (IBC) is a less common type of breast cancer, accounting for 1-3% of all breast cancers. Typically, IBC 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 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. This type of breast cancer only accounts for about 1% of all cases of breast cancer.
Phyllodes tumors are rare breast tumors that develop in the connective tissue (stroma) of the breast and grow in a leaf-like pattern. Phyllodes tumors rarely spread outside the breast even though they tend to grow quickly.
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.