Every Type of Breast Cancer, Explained

Getting a breast cancer diagnosis is scary, but knowing what type you have can help ease some of your fears-and understanding the type will help you and your doctor determine the best treatment for you.

When it comes to figuring out the type of breast cancer and how to treat it, there are usually three factors to consider, says ocologist Dr Adam Brufsky. “Is it invasive? And is it hormone receptor positive or HER2 positive? Once you have those three factors together, you can figure out how to treat it,” he explains.

Most breast cancers are carcinomas, which means they start in cells that line organs and tissues throughout the body. Breast cancers tend to fall into two categories: “in situ,” which means it hasn’t spread to surrounding tissue and is therefore more treatable, and “invasive,” which means it has spread to surrounding tissue. There’s also “metastatic” breast cancer, which indicates that it has spread to other parts of your body, most commonly the lungs, bones, liver or brain.

Here are the types of breast cancer you need to know about.

In situ breast cancers

Ductal carcinoma in situ (DCIS)

Considered pre-cancer, DCIS is the most common type of non-invasive breast cancer. It starts in a milk duct and is highly treatable. Nearly all women with this early stage of breast cancer can be cured. Over time, DCIS may progress to invasive breast cancer.

Lobular carcinoma in situ (LCIS)

Also known as lobular neoplasia, LCIS is not cancer (even though it has carcinoma in its name). Instead, cells that look like cancer cells grow in the milk-producing lobules of the breast.

Invasive breast cancers

Invasive ductal carcinoma (IDC)

This is the most common type of breast cancer, making up 80 percent of invasive cases. IDC starts in the cells that line a milk duct in the breast, breaks through the wall of the duct, and grows into nearby breast tissues. From there, is can spread (metastasize) to other parts of the body through the lymph system and bloodstream.

Invasive lobular carcinoma (ILC)

This type of breast cancer starts in the lobules (milk-producing glands) and accounts for approximately 10 percent of invasive breast cancers. ILC may be harder to detect than IDC via a physical exam or imaging, like a mammogram. And compared to other kinds of invasive carcinoma, about 1 in 5 women with ILC might have cancer in both breasts. Like IDC, it can spread to other parts of the body.

Rare breast cancers

Inflammatory breast cancer (IBC)

This rare breast cancer causes swelling and redness in the breast, which is caused by cancer cells blocking lymph vessels in the skin. In addition to swelling and redness, you might experience pitting or thickening of the skin causing it to look and feel like an orange people. If you have any of these symptoms, see your doctor right away.

Paget disease of the nipple

This rare type of breast cancer starts in the breast ducts and spreads to the nipple and areola (the darker circle of skin). It can look very similar to eczema (very dry skin) of the nipple. You may also experience blood or yellow fluid coming out of the nipple, and it may also burn or itch. Paget disease usually affects only one nipple and tends to be linked to either ductal carcinoma in situ (DCIS) or infiltrating ductal carcinoma.

Phyllodes tumour

These are rare breast tumours that develop in the connective tissue of the breast (as opposed to carcinomas, which develop in the ducts or lobules). Most are benign (not cancer), but 1 out of 4 are malignant (cancer). Phyllodes tumours are most common in women in their 40s, but women of any age can have them.

Angiosarcoma of the breast

Making up less than 1 percent of all breast cancers, angiosarcoma starts in the cells that line blood vessels or lymph vessels. It can involve the breast tissue or the skin of the breast, and is sometimes related to prior radiation treatment of the breast.

Breast cancer subtypes

“We tend to think of breast cancer as one condition, but there’s a lot of personalized care that goes into treating it,” says oncologist Dr Megan Kruse. “As we learn more about breast cancer, we’re dividing it into different subtypes, which can help improve outcomes.”

There are three main subtypes and they’re grouped by three genetic markers your doctor will look for on a biopsy specimen: the oestrogen receptor, progesterone receptor, and a protein called HER2, notes Dr Kruse. If the cancer is negative for all three of those things, it’s called triple negative breast cancer.

Knowing your cancer’s hormone receptor and HER2 status is critical when it comes to determining treatment. Here’s what you need to know about each breast cancer subtype:

Hormone receptor positive (luminal) breast cancer

Some breast cancers are fueled by the hormones oestrogen and/or progesterone. “Oestrogen is the female hormone that makes us women, but it’s also a growth factor that can help breast cancer cells grow,” explains oncologist Dr Jennifer Specht. Knowing whether your cancer is sensitive to these hormones is a critical part of determining the best treatment. If you test positive for either the oestrogen or progesterone hormone, your breast cancer is considered hormone receptor positive breast cancer and will likely be treated with hormonal therapies.

HER2-positive breast cancer

This is the other main type of breast cancer, says Dr Specht, and it’s called HER2-positive because it has too many copies of a protein called human epidermal growth factor receptor 2 (HER2). This type can include cancers that are hormone receptor positive or negative.

Triple negative breast cancer

Making up about 17 percent of all breast cancers that are diagnosed, triple negative breast cancer gets its name because it’s negative for all three markers: oestrogen, progesterone, and HER2. “Triple negative breast cancer tends to be the most aggressive in terms of the most difficult and hardest prognosis, and the more aggressive of the three types,” says Dr Specht. It’s more prevalent in premenopausal women and those with a BRCA1 gene mutation.