What is Kaposi's sarcoma?

Kaposi’s sarcoma is a cancer of the cells that line blood or lymphatic vessels.

The condition is the result of infection caused by Kaposi’s sarcoma-associated herpesvirus or human herpesvirus 8.

When the cells lining blood and lymphatic vessels become infected with Kaposi’s sarcoma-associated herpesvirus, the cells often divide too much and have an extended life. These alterations in cells may possibly lead the change into cancer cells.

Risk factors and symptoms

Most people who are infected with Kaposi’s sarcoma-associated herpesvirus do not go on to develop Kaposi’s sarcoma. However, individuals with HIV infection, those who have taken certain medications after an organ transplant or those of older age are at increased risk.

Incidence of Kaposi’s sarcoma-associated herpesvirus varies across the world. Data suggest that fewer than 10% of Americans are infected with the virus, whereas more than 90% of the population in certain areas of Africa have the virus.

In the U.S., those with HIV infection are more likely to have Kaposi’s than the general population.

Kaposi’s sarcoma typically presents itself as tumors on the skin or inside the mouth; however, tumors may develop in the lymph nodes, lungs or digestive tract. Brown, red or purple lesions may appear on the skin. These lesions — most often found on the legs or face — usually are not painful, but they sometimes cause painful swelling in the legs or feet.

When lesions are present in the lungs, liver or digestive tract, serious complications may arise. Tumors that develop in the digestive tract may cause bleeding, whereas people with tumors in the lungs may experience difficulty breathing.

Types and subtypes

Kaposi’s sarcoma was rare in the United States before the AIDS epidemic, according to the American Cancer Society.

During this time, approximately two new cases of the condition were found per 1 million people each year. These types of Kaposi’s sarcoma were known as classic and transplant-associated. It is estimated that about 1 in 200 patients who undergo transplant in the U.S. will be diagnosed.

However, the majority of these patients already were infected with Kaposi’s sarcoma-associated herpesvirus before transplant. The virus did not cause problems because patients’ immune systems suppressed it. Once these patients start taking medication to suppress their immune system, Kaposi’s sarcoma then develops.

At the height of the AIDS epidemic in the 1990s, annual diagnosis rates of Kaposi’s sarcoma increased to about 47 cases per 1 million people.

This type is known as HIV-associated or AIDS-associated Kaposi’s sarcoma.

Once newer treatment options for AIDS became available, Kaposi’s sarcoma became less common in the United States. Current estimates suggest it is diagnosed at a rate of six cases per 1 million people each year.

Other Kaposi’s sarcoma types include African, epidemic and non-epidemic Kaposi’s sarcoma.

Treatments

Individuals with HIV/AIDS are more likely to develop Kaposi’s sarcoma. Therefore, most physicians recommend regular examination by health care providers experienced in recognizing the condition.

Once someone has been diagnosed with Kaposi’s sarcoma, tests are conducted to see if the cancer cells have spread to other parts of the body.

Treatment options are dependent upon certain factors. Kaposi’s sarcoma tends to develop in several areas of the body at the same time, so the function of the immune system, as well as the number, location and size of lesions, help determine treatment choices.

Examples of treatments include local therapy, radiation therapy, chemotherapy and immunotherapy. In certain cases, two or more of these treatments may be used in combination.

On the horizon

Researchers are trying to identify more effective ways to prevent and treat Kaposi’s sarcoma. Studies designed to examine HIV vaccines and antiretroviral therapies are expected to have a significant impact on AIDS-associated Kaposi’s sarcoma.

The odds of being diagnosed with Kaposi’s sarcoma have been greatly reduced with the development of drugs that help control HIV/AIDS.

Other areas of research include topical drugs and angiogenesis inhibitors to shrink Kaposi’s sarcoma skin lesions, as well as the effect of boosting the immune system with drugs such as interleukin-12. Other therapies used to treat other cancer types also are being evaluated for the treatment of Kaposi’s sarcoma.

Additionally, researchers are examining whether antiviral drugs that target Kaposi’s sarcoma-associated herpesvirus may be used to also treat Kaposi sarcoma.

More information is available at these websites:

www.cancer.gov/types/soft-tissue-sarcoma/patient/kaposi-treatment-pdq