Types of Breast Cancer

There are many different types of breast cancer. Breast cancer can be categorized as either invasive or non-invasive and can be found in different parts of the breast. Each different type of breast cancer impacts different cells in the body, which helps determine how fast the cancer grows and spreads. Understanding the different types of breast cancer can help navigate the care needed. Here, we take a closer look at each type.

Carcinoma In Situ

In its earliest stages, cancers are referred to as “carcinoma in situ” meaning cancer in the original place. Carcinoma in situ can include:

• Ductal carcinoma in situ (DCIS): A non-invasive cancer that involves abnormal cells being found in the milk duct, but not spreading outside of the duct to other breast tissue. This is often found in a routine mammogram. If left untreated, DCIS can progress into invasive cancer.
• Lobular carcinoma in situ (LCIS): This is when abnormal cells are discovered in the lobules of the breast but have not spread to the surrounding breast tissue.

Invasive Ductal Carcinoma (IDC)

Invasive ductal carcinoma (IDC) is the most common type of breast cancer, accounting for 70 to 80% of all breast cancer diagnoses. IDC is when cancer begins in the duct of the breast and has spread to other breast tissues. Less common forms of IDC include:

• Medullary carcinoma: Accounting for 3 to 5% of all breast cancers—when the tumor is a soft, fleshy lump akin to a part of the brain called the medulla.
• Mucinous carcinoma: When the tumor floats in pools of mucin, a key ingredient in mucus.
• Tubular carcinomas: Usually less than 1cm in size and have a tubelike structure.
• Papillary carcinoma: This accounts for less than 1 to 2% of invasive breast cancers.

Invasive Lobular Carcinoma (ILC)

Invasive lobular carcinomas (ILC) account for about one in 10 invasive breast cancers. ILC begins in the lobules—or milk-producing glands of the breast. It can then spread throughout the body. ILC can be categorized into different subtypes based on how cancer cells appear when viewed through a microscope. These subtypes are:

• "Classic” ILC: The cells appear in a single file formation, are similar to each other and tend to be small.
• “Solid” ILC: When the cells appear in large sheets.
• “Alveolar” ILC: When the cells are grouped together and grow in collections of 20 or more.
• “Tubulolobular” ILC: Similar to the classic type with single file formations, however, the cells have a tube like structure.
• Mixed invasive Ductal-Lobular: This has features of both ILC and IDC.

Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive cancer and makes up 10% to 15% of all breast cancers. In this cancer, the cancer cells are lacking estrogen and progesterone receptors and don’t make much of a protein known as HER2.

This cancer grows and spreads faster than other forms of invasive breast cancer. It has limited treatment options and a worse prognosis. When compared with HER2 positive cancers, TNBC has the lowest survival rates.

Inflammatory Breast Cancer (IBC)

Inflammatory breast cancer is uncommon, accounting for just 1 to 5% of all breast cancers. IBC differs from other cancers in symptoms, outlook, and treatment options. In IBC, cancer cells block the lymph vessels in the skin, the result is the breast looking red, purple, or inflamed. IBC can be challenging to diagnose as it does not look like other cancers and may not have a breast lump that would appear on a mammogram.

All IBC cases begin at stage 3 because by the time it is diagnosed, the cancer cells have already grown into the skin. IBC is the only form of breast cancer that warrants urgent immediate treatment. It is estimated that 20% to 40% of IBC cases are triple-negative.

Paget’s Disease of the Breast

Paget’s disease of the breast accounts for less than 5% of all breast cancers and involves cancer cells gathering in or around the nipple and the skin surrounding it, called the areola. Symptoms can sometimes be mistaken for eczema or dermatitis and can include itchy or tingling feelings in the nipple or areola, flaking or crusting of the skin, and discharge from the nipple. Paget cells are malignant cells found in the surface layer of the skin in the nipple and areola. Under a microscope, they appear large and round and are a sign of Paget's disease of the breast.

Angiosarcoma of the Breast

Angiosarcoma is a rare form of cancer that begins in the endothelial cells, that line the blood and lymph vessels. There are two forms of angiosarcoma of the breast:

Primary angiosarcoma: This occurs in women who have never been treated for breast cancer before.

Secondary angiosarcoma: This occurs in women who have already been treated for breast cancer.

In angiosarcoma, there can be necrosis, as well as hemorrhage.

Phyllodes Tumor

Phyllodes tumors account for less than 1% of all breast cancer tumors. They often grow quickly but don’t typically spread outside the breast. Phyllodes tumors grow in the connective tissue of the breast, called the stroma. The stroma comprises the fatty tissues and ligaments surrounding the ducts, lobules, lymph, and blood vessels in the breast. These tumors are most common in women in their forties. Women with a rare inherited genetic condition called Li-Fraumeni syndrome are at increased risk for these tumors. One in four cases of phyllodes tumors are cancerous, most are benign.

Male Breast Cancer

Breast cancer in men is rare, accounting for less than 1% of all breast cancers. Both men and women have breast tissue. Like female cases of breast cancer, the risk of cancer in men increases with age. The average age of diagnosis in men is 68. As in women, symptoms of breast cancer in men can include:

• Lump in the breast
• Pain in the nipple
• Inverted nipple
• Nipple discharge
• Enlarged lymph nodes under the arms
• Sores on the nipple or on the areola

The occurrence of breast cancer in men is less than in women because despite also having breast tissue, male breasts are mainly fat and fibrous tissue with fewer ducts and lobules. In women, most cancers develop in the ducts and lobules.

A Word From Verywell

Reading about the many forms of breast cancer can be overwhelming. But there are steps you can take to be proactive. Regular mammograms and recognizing any changes in your breasts can assist with early diagnosis and treatment, if necessary. If you experience lumps, puckering, dimpling, crusting, or redness of the breast or nipple, speak with your healthcare provider.