Do We Know What Causes Kaposi Sarcoma?

Kaposi sarcoma (KS) is caused by infection with a virus called the Kaposi sarcoma associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8). KSHV is in the same family as Epstein-Barr virus (EBV), the virus that causes infectious mononucleosis (mono) and is linked to several types of cancer.

In KS, the cells that line blood and lymphatic vessels (called endothelial cells) are infected with KSHV. The virus brings genes into the cells that can cause the cells to divide too much and to live longer than they should. These types of changes may eventually turn them into cancer cells.

KSHV infection is much more common than KS, and most people infected with this virus do not get KS. Many people infected with KSHV will never show any symptoms. Infection with KSHV seems to be needed to cause KS, but in most cases infection with KSHV alone does not lead to KS. Most people who develop KS also have a weakened immune system, due to HIV infection, organ transplant, older age, or some other factor.

The percentage of people infected with KSHV varies in different places around the world. In the United States, studies have found that less than 10% of people are infected with KSHV. The infection is more common in people infected with HIV than in the general population in the United States. KSHV is more common in men who have sex with men than in men who only have sex with women.

In some areas of Africa, more than 90% of the population shows signs of KSHV infection. In these areas the virus seems to spread from mother to child. KSHV is also found in saliva, which may be one of the ways it is passed to others.

For more on infections and their role in cancer, see Infections That Can Lead to Cancer.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: August 8, 2014 Last Revised: February 9, 2016

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