Types of breast cancer

If you’ve been diagnosed with breast cancer, you may soon be entering a world full of lots of technical information. One of the things you’ll be learning about is all the different ways breast cancer can be described. Positive or negative. Invasive or in situ. Let’s start with some of the basics.

Four main types of breast cancer

Defining breast cancer types starts with where they originated. Most breast cancers start in the milk lobules (glands in the breast that make milk) or in the milk ducts (tubes that carry milk from the lobules to the nipple).

This definition also considers whether the breast cancer is invasive (has spread to other areas of the breast) or in situ (staying in the place where it started). Identifying these things about the breast cancer gives us the four main types of breast cancer:

• Ductal carcinoma in situ (DCIS): Found in the milk ducts and hasn’t grown into other areas of the breast.
• Invasive ductal carcinoma (IDC): Found in the milk ducts and has spread to other breast tissues.
• Lobular carcinoma in situ (LCIS): Found in lobules and hasn’t grown into other areas of the breast. This is considered a breast condition, not a cancer.
• Invasive lobular carcinoma (ILC): Found in lobules and has spread to other breast tissues.

The most common types of breast cancer are the invasive types. According to the American Cancer Society, about 75% of breast cancers diagnosed in women and men are invasive ductal carcinomas (IDC). Invasive lobular carcinomas (ILC) are the next most common.

Rarely, breast cancers may start in the muscles, fat or blood vessels of the breast.

Screening mammograms are the best protection against any type of breast cancer since they help find breast cancer early – when it’s most easy to treat.

Other breast cancer types

Breast cancer types may also be described based on the shape or appearance of the cancer cells or on what parts of the breast they affect. These are other ways to name and describe breast cancer.

• Angiosarcoma: Cancer that grows in the lining of blood vessels or lymph vessels. Occurs most in people older than 70.
• Breast papilloma: A rare non-cancerous tumor that forms in the milk duct near the nipple.
• Inflammatory breast cancer: A rare kind of breast cancer that makes the skin of the breast look inflamed. It’s aggressive and fast-growing and often has no tumor or lump. One of the most serious kinds of invasive breast cancer.
• Medullary carcinoma: A tumor that is soft and gray. The area of cancer may feel spongy instead of like a lump.
• Metastatic breast cancer: Breast cancer that spreads to other parts of the body besides the breast tissues and nearby lymph nodes.
• Paget’s disease: A rare cancer that affects the skin of the nipple and areola (the dark skin surrounding the nipple). The affected breast often has internal tumors.
• Papillary carcinoma: This cancer has finger-like growths that stick out from the cells.
• Tubular carcinoma: These cancer cells are shaped like tubes and feel spongy instead of like a lump. They’re more likely after the age of 50.

Testing breast cancer cells

After breast cancer cells are removed from the body through biopsy or surgery, they’re sent to a pathologist for testing. They’ll be tested to find out if they’re inherited or genetic. Breast cancer has been found to be related to mutations in many genes. BRCA1 and BRCA2 are the most common of those genes.

Testing can apply to any types of breast cancer. The results will guide the treatment that is recommended for you. Some tests check for cells related to estrogen, progesterone and the HER2 gene.

HER2 testing

Checks tissues for the presence of the HER2 protein, which helps breast cancer cells grow quickly. If there’s too much of it present, it’s described as HER2-positive. If not, it’s HER2-negative.

Hormone receptor testing

Some breast cancers grow more due to the hormones estrogen or progesterone. Newly diagnosed breast cancers often test positive for reactions to estrogen or progesterone. They’re referred to as:

• Estrogen receptor-positive (ER-positive)
• Progesterone receptor-positive (PR-positive)

If the breast cancer tissue doesn’t respond to either hormone, the cancer is called:

• Estrogen receptor-negative (ER-negative)
• Progesterone receptor-negative (PR-negative)

Combined breast cancer testing categories

When breast cancer cells test negative for estrogen, progesterone and HER2, they’re referred to as triple negative breast cancer. It’s one of the most serious types of breast cancer because it resists some of the most common treatments. Chemotherapy can be used for triple negative breast cancer.

If breast cancer cells test positive for estrogen, progesterone and HER2 they’re referred to as triple positive breast cancer . These cancers have more options for treatment because they can be treated with medications that target hormone receptors and HER2 proteins.