Editor's note: This document provides a brief description of inflammatory breast cancer. For comprehensive information on this and other types of breast cancer, please refer to our document called Breast Cancer.

What is inflammatory breast cancer?

Inflammatory breast cancer (IBC) is rare. It is very important to distinguish IBC from other types of breast cancer because there are major differences in its symptoms, prognosis (outlook), and treatment.

Inflammatory or inflammation refers to changes in the body's tissues that can be caused by injury, irritation, or infection. This typically results in redness, warmth, and swelling in the involved parts of the body from increased blood flow and the buildup of white blood cells.

One type of breast cancer is called inflammatory breast cancer because the affected breast displays the same symptoms that may occur with inflammation, like swelling, skin redness, and an orange peel like texture of the skin. But this does not mean that IBC (or its symptoms) is caused by infection or injury. The symptoms of IBC are caused by cancer cells blocking lymph vessels in the skin.

There is some disagreement in the numbers, but IBC probably accounts for about 1% of all breast cancers diagnosed in the United States. Some experts believe that IBC may be more common, but diagnosing it is often difficult. This can mean the disease is not being reported as often as it should.

How is inflammatory breast cancer different from the more common types of breast cancer?

Inflammatory breast cancer causes symptoms that are often different from those of more common breast cancers. It rarely causes a breast lump, and it might not show up on a mammogram. Because it doesn't look like a typical breast cancer, it can be harder to diagnose.

IBC tends to occur at a younger age than the more common form of breast cancer (at an average age 52 versus 57 for non-inflammatory breast cancer). Also, African-American women appear to be at higher risk of IBC than white women. It also is more common among women who are overweight or obese.

IBC also tends to be more aggressive—it grows and spreads much more quickly— than more common types of breast cancer. By definition, it is never found at an early stage. It is always at least stage IIIB (locally advanced) when it is first diagnosed because the breast cancer cells have grown into the skin. Often, though, it has already spread to distant parts of the body when it is diagnosed, making it stage IV (metastatic). The advanced stage of IBC, along with the tendency to grow and spread quickly, makes it harder to treat successfully than most other types of breast cancer.