Understanding the Different Types of Breast Cancer

Jake Newby

| 5 min read

Knowing the many different types of breast cancer is important because the treatment required depends on the type of cancer an individual has.
Most types of breast cancers can be categorized as adenocarcinomas of the breast. Adenocarcinomas – which make up 90% of breast cancers – develop in the glands that line the organs. These tumors are found in many other common cancers, like stomach, prostate, pancreatic, colorectal and lung cancers.
Dividing the types of breast cancer between invasive and noninvasive is broad but may be the best way to break them down. Metastatic breast cancer, HER2 breast cancer and triple negative breast cancer are three other types described below.

Invasive breast cancer types

Most breast cancers are invasive, which is a term used to describe a person’s breast cancer spreading into surrounding breast tissue. The most common types of invasive breast cancer are known by the acronyms “IDC” and “ILC.”
Invasive (infiltrating) ductal cancer (IDC): IDC is the most common type of breast cancer. According to the American Cancer Society (ACS), about 8 in 10 invasive breast cancers are IDCs, so 80% of all cancer diagnoses.
IDC starts in the milk ducts and spreads to other parts of the breast by breaking through the wall of the duct. Depending on how early IDC is detected and how aggressive the tumor is, it could metastasize and spread to lymph nodes and other parts of the body. IDC is also the type of breast cancer that most commonly affects men.
Invasive lobular cancer (ILC): Over 10% of invasive breast cancers are invasive lobular carcinomas, according to the National Breast Cancer Foundation.
ILC starts in the lobules, which are the breast glands that make milk. Like IDC, it can metastasize to other parts of the body. ILC can be harder to detect during physical exams and imaging than IDC. Invasive lobular cancer doesn’t always appear clearly on a mammogram, instead an MRI might be needed.
Compared to other types of invasive carcinoma, ILC is more likely to affect both breasts. About 1 in 5 women with ILC might have cancer in both breasts at the time they are diagnosed, per the ACS.
Inflammatory breast cancer (IBC) – which may be detected in the ducts or lobules – is more aggressive than other types of breast cancer but is also more rare, accounting for only 1% to 5% of all breast cancers. IBC causes symptoms of breast inflammation like swelling and redness, which is caused by cancer cells blocking lymph vessels in the skin, leading to the inflamed appearance.

Treating invasive breast cancer

Treatment of invasive breast cancer depends on how advanced the stage of the cancer is. Tumor removal surgery is a common option. In general, most treatment plans include a combination of surgery, radiation, hormone therapy, chemotherapy, and targeted therapies. Some are local, meaning they only target the area around the tumor. Systemic treatments target the entire body with cancer fighting agents.

Noninvasive breast cancer types

Ductal Carcinoma in Situ (DCIS): In DCIS, abnormal cells are found in the lining of the breast milk duct. This is a very early-stage cancer that is highly treatable. But if left untreated, it could spread to surrounding breast tissue.
Lobular Carcinoma in Situ (LCIS): This condition is diagnosed when abnormal cells are found in the lobules of the breast. It is also highly treatable and rarely advances to the invasive cancer stage. But according to the National Breast Cancer Foundation, having LCIS in one breast increases the risk of developing breast cancer in either breast. Both DCIS and LCIS are considered slow-growing tumors.

Metastatic breast cancer

Also classified as stage IV breast cancer, metastatic breast cancer is the most advanced stage of breast cancer. About 1 in 8 American women will develop breast cancer in their lives. It occurs when cancer spreads from a person’s breast to other parts of their body. The area of the spread is called a “metastasis.” This type of cancer can affect people who had breast cancer without seeking treatment.
When breast cancer metastasizes, it usually spreads to the lungs, liver, bones, or brain, leading to varying symptoms to each body part or organ. There is no cure for metastatic breast cancer, but technology and treatment methods continue to improve and have allowed metastatic breast cancer patients to have a longer, better quality of life.

HER2 breast cancer

About 15% to 20% of breast tumors have higher levels of a protein known as HER2, per the ACS. HER2 is a protein that causes breast cancer cells to grow quickly. Breast cancer cells with abnormally high levels of HER2 are called HER2-positive. These cancers tend to grow and spread faster than breast cancers that are HER2-negative. While HER2 is more aggressive than other types of breast cancer, it is treatable with drugs that target the HER2 protein.
All invasive breast cancers should be tested for HER2 either on the biopsy sample or when the tumor is surgically removed.

Triple negative breast cancer

Triple negative breast cancer (TNBC) accounts for about 10% to 15% of all breast cancers. It involves the same signs and symptoms as other common types of breast cancer and occurs when cancer cells don’t have estrogen receptors, progesterone receptors and either produce too few or too manyHER2, which is a protein that helps breast cancer cells grow quickly. These cells tests “negative” on all three tests, making this type of cancer very difficult to treat.
TNBC is usually more common in women younger than age 40, Black women, and women with a BRCA1 mutation. TNBC tends to grow quickly, is more likely to have spread at the time it’s found and is more likely to resurface after treatment as opposed to other types of breast cancer, according to the ACS. Survival rates for TNBC are generally not as high as they are for other types of breast cancer.
Breast cancer screenings save lives. Blue Cross Blue Shield of Michigan or Blue Care Network plans cover many preventive care services, including mammography, when performed by in-network providers to get all the information about what your plan covers and any potential out-of-pocket costs, look at your Summary of Member Benefits or call the number on the back of your ID card.
Talk to your primary care provider (PCP) as soon as possible about your breast cancer risk, when you should begin your screenings and, if you need one, schedule a screening today.
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Photo credit: Getty Images

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