Breast cancer is not a single disease, but rather a broad term that covers a number of different types of the disease. Because of this, your treatment plan may look completely different than another patient’s treatment plan, all because of your specific breast cancer type. Knowledge, however, can be power. Use this guide to learn more about breast cancer types, how they are determined, and how they are classified so you can have a better idea of what to expect.
After a breast cancer diagnosis, your cancer team will need to determine a few important details about your breast cancer. The preliminary pathology report, from a biopsy, help oncologists gather information about the breast cancer like the stage, hormone receptor status, and the specific type of breast cancer you have. The sooner your type and other details are determined, the sooner you can get on the path to treatment and recovery. 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. Several factors will be looked at, which include:
- Where the cancer cells originated
- 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 Types
Breast cancer occurs in two broad categories: 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 cancer type is very rare, a lump or tumor may never form at all.
Common Categories of Breast Cancer
Some breast cancers are more common than others. These common types of breast cancer include:
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. This is the most common type of breast cancer, accounting for approximately 80% of all breast cancers.
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. 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.
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) is also sometimes called lobular neoplasia. 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.
Less Common Types of Breast Cancer
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
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 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. These tumors develop in the connective tissue (stroma) of the breast and grow in a leaf-like pattern. Although phyllodes tumors tend to grow quickly, they rarely spread outside the breast.
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.