Did you know there are several different kinds of breast cancer? But how are they different? 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. 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.
Determining Your Breast Cancer Type
There are several factors that are looked at during the process of determining the type of breast cancer that a patient has, including:
Origin point of the cancer cells
How the breast cancer cells look under the microscope
How the cancer cells react to hormones
The breast cancer cells’ genetic makeup
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, the milk ducts or lobules in the breast. Most breast cancers start in the ducts or lobes and are called ductal carcinoma or lobular carcinoma.
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
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, and it is the most common type of non-invasive breast cancer. DCIS isn’t considered life-threatening, but it can increase the risk of developing 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, and it is only located in the lobules. 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 developing breast cancer in both breasts later on.
Invasive ductal carcinoma
Invasive 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. This 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 the lymph nodes and 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.
Invasive breast cancers will most likely require an oncology team to create a treatment plan using one or more of the following:
- Hormone therapy
- Biologic therapy
- Radiation therapy
Less Common Types of Breast Cancer
Inflammatory breast cancer
A rare, fast-growing type of breast cancer, accounting for 1-5% of all breast cancers is Inflammatory breast cancer (IBC). IBC often appears to be a breast infection (the breast is 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 and swelling in the breast. Because this cancer is very aggressive and has a high risk of spreading, a combination of treatment modalities is often used.
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. The nipple and areola can become irritated with scaly, red, itchy areas. This type of breast cancer only accounts for less than 5% of all cases of breast cancer. Although it is usually in situ or confined to the site where it started, the disease can also be invasive.
A few other rare types of breast cancer are diagnosed each year including:
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.