What Are the Different Types of Breast Cancer?

Facing a breast cancer diagnosis can be an overwhelming experience, filled with uncertainty and fear, but knowledge is a powerful tool.

Here's a guide on the different types of breast cancer, shedding light on ductal carcinoma in situ (DCIS), invasive ductal carcinoma, invasive lobular carcinoma, phyllodes tumor, Paget’s disease of the breast, and angiosarcoma of the breast.

What are the types of breast cancer?

Breast cancer remains a formidable health challenge in the United States. The American Cancer Society projects 297,790 new cases of invasive breast cancer and 55,720 new cases of ductal carcinoma in situ (DCIS) this year. In all, 43,700 women are expected to lose their lives to this disease.

DCIS (ductal carcinoma in situ)

About 20% of breast cancers are ductal carcinoma in situ. DCIS is characterized by abnormal cells confined within a milk duct in the breast, according to the Mayo Clinic. It often goes undetected because it causes no noticeable symptoms.

“Most cases are diagnosed in a mammogram before causing any symptoms,” Dr. Bonnie Sun, of Johns Hopkins' breast center, said in a Hopkins site.

DCIS is considered the earliest form of breast cancer, remaining noninvasive, and posing a low risk of becoming invasive.

Regular mammograms play a crucial role in early detection of DCIS, ensuring a higher chance of successful treatment.

Invasive breast cancers

When breast cancer spreads beyond the milk ducts and into surrounding breast tissue, it is known as invasive breast cancer. This category encompasses the majority of breast cancer cases, with diverse types exhibiting unique characteristics.

“The two most common are invasive ductal carcinoma and invasive lobular carcinoma," the American Cancer Society says.

Invasive ductal carcinoma

Invasive ductal carcinoma, known also as infiltrating ductal carcinoma or IDC, is the most prevalent form of breast cancer, accounting for about 75% of all cases, according to Breastcancer.org.

The stage of IDC is assessed based on characteristics like size and hormone receptor status. Stages 1, 2 and 3 are early-stage cancers, while stage 4 means cancer has spread to other areas, such as the bones or liver.

Inflammatory breast cancer

Inflammatory breast cancer (IBC) is a rare subtype, comprising 1% to 5% of all cases of breast cancer. Though it is a type of invasive ductal carcinoma, the symptoms, prognosis and treatment of IBC differ. The presence of cancer cells blocking lymph vessels in the skin causes inflammation, leading to visible signs of redness and swelling in the breast.

Due to its aggressive nature, IBC grows rapidly. By the time it is diagnosed, it often has spread, and it is more likely to return after treatment. Consequently, survival rates for IBC are generally lower compared to other types of breast cancer.

Invasive lobular carcinoma

Invasive lobular carcinoma (ILC) is the second most common type of breast cancer, according to Breastcancer.org, following invasive ductal carcinoma. About 10% of breast cancer cases are ILC. The term "invasive" indicates that the cancer has extended beyond its original site in the milk-producing glands.

Triple-negative breast cancer (TNBC)

Primary triple-negative invasive lobular breast carcinomas (TN-ILC) are rare. They are tumors characterized by cancer cells without estrogen or progesterone receptors (ER or PR) and minimal or no HER2 protein, according to the American Cancer Society.

This aggressive tumor type exhibits rapid growth, increased risk of spread and higher chances of recurrence, necessitating chemotherapy as a key part of the treatment plan, according to Johns Hopkins Medicine. Comprehensive research and targeted therapies enhance outcomes.

HER-2 positive breast cancer

HER2-positive breast cancer is identified by the presence of the human epidermal growth factor receptor 2 (HER2) protein, which accelerates the growth of cancer cells. About 1 in 5 breast cancers have additional copies of the gene responsible for producing HER2, according to the Mayo Clinic.

This subtype tends to be more aggressive than others. But targeted treatments have proven highly effective, leading to a relatively positive prognosis for HER2-positive breast cancer.

Phyllodes tumor

A phyllodes tumor is a rare form that arises in the breast's connective tissue. While most people associate breast tissue with fatty and glandular tissue, the connective tissue plays a crucial role in providing support and structure. While the majority of phyllodes tumors are non-cancerous, the Cleveland Clinic notes that about 25% are cancerous.

Cancerous phyllodes tumors account for a mere 0.05% of all breast malignancies. Unlike the more common breast cancers affecting glandular tissues (milk ducts and lobules), phyllodes tumors are classified as a type of sarcoma, which specifically targets the connective tissue.

Paget’s disease of the breast

Paget's disease of the breast, also known as Paget's disease of the nipple or mammary Paget's disease, is a rare form of cancer affecting the skin of the nipple and the areola, the darker skin surrounding it. Often, individuals with Paget's disease of the breast have underlying tumors within the same breast, classified as either ductal carcinoma in situ or invasive breast cancer.

Although it occurs in both sexes, the U.S. National Cancer Institute says the majority of cases are observed in women. About 1% to 4% of all breast cancer cases involve Paget's disease. Its survival rates are slightly lower than for other types of breast cancer, with a five-year relative survival of 82.6% in the United States between 1988 and 2001.

Angiosarcoma of the breast

Angiosarcoma is a very rare form of cancer that represents less than 1% of breast cancers, according to Johns Hopkins Medicine.

Primary angiosarcoma occurs in patients who have never been treated for breast cancer and secondary angiosarcoma occurs in patients who have previously been treated.

A thickened area of skin, a lump or discolored rash or bruised appearance on the skin of the breast or arm are possible signs of primary angiosarcoma. Symptoms of secondary angiosarcoma can include swelling in the breast or arm, a painful breast lump and discolored rash or bruised appearance

Radiation-induced angiosarcoma (RIAS) is another form of angiosarcoma.

“RIAS is a secondary type of angiosarcoma in the breast that is associated with having received radiation therapy for breast cancer,” Dr. Melissa Suzanne Camp said in a Johns Hopkins site. She is program director of the Halsted General Surgery Residency Program at Hopkins Medicine. “The incidence of RIAS is very rare, about 0.2%, and typically shows up in patients six to 10 years after they’ve had radiation.”

Early detection of breast cancer

Learning about the different types of breast cancer is vital for early detection and personalized treatment. Regular self-breast examination and mammograms play important roles in spotting any abnormalities early on, enabling timely intervention and improving survival rates, according to Breastcancer.org.