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What is Kaposi Sarcoma?

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By Editorial Team

5 min read

Reviewed by: HU Medical Review Board | Last reviewed: May 2017.

Kaposi sarcoma (KS) is a rare cancer. It develops in the cells that line the lymph vessels and blood vessels and usually causes skin lesions. In the United States today, there is 1 case of KS per 200,000 people.1

A virus called “Kaposi sarcoma associated herpesvirus” (abbreviated: KSHV) causes KS. Not everyone infected with KSHV develops KS. However, KSHV infection may lead to KS in a person with a weakened immune system. KSHV causes gene mutations that lead to out-of-control cell growth and survival. Tumors appear on the skin, mouth, and internal organs.2 These tumors are called lesions.

What are the types of Kaposi sarcoma?

There are five types of KS. Each type is defined by the population it affects. The disease course is different for each type.

HIV-related Kaposi sarcoma (also called Epidemic Kaposi sarcoma).

HIV-related KS is the most common type of KS in the United States.2 A person may be infected with HIV for many years without developing AIDS. AIDS develops when HIV has seriously damaged the immune system. A person with a very weak immune system who becomes infected with KSHV is more likely to develop KS.2,3

HIV-related KS is severe, causing widespread lesions.3 In one study, nearly two-thirds of patients developed numerous skin lesions all over the body.

Classic Kaposi sarcoma (also called Mediterranean Kaposi sarcoma).

Classic KS is most common in older men (50 to 70 years) of Italian or Jewish ancestry.3 In this population, the immune system may be somewhat weakened due to age.

This form of KS develops slowly and is relatively harmless.3 Lesions typically appear on the ankles, soles, and lower legs. The original lesion usually grows slowly. Eventually other lesions develop. Up to 33% of people with classic KS develop a second cancer.3

Endemic Kaposi sarcoma (also called African Kaposi sarcoma).

Endemic KS occurs in Equatorial Africa.2 It can take one of two courses. In some patients, it is similar to classic KS with slow growing lesions.3 In other patients, it is very aggressive and quickly spreads to the lymph nodes and other internal organs.3 Unlike classic KS, endemic KS typically affects people under age 40, including young children.2,3 The immune system may be weak due to malnutrition, malaria, or other long-term infection.2

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Iatrogenic Kaposi sarcoma (also called Transplant-Related or Immunosuppressive-Related Kaposi sarcoma).

A person who has had organ transplantation must take immunosuppressant medications. Immunosuppressant medications weaken the immune system. This prevents the immune system from attacking the new organ. Unfortunately, this also can lead to the development of KS.

In many cases, iatrogenic KS only affects the skin. However, lesions can occur in the mucous membranes or internal organs.3

Non-Epidemic Kaposi sarcoma in HIV-Negative Men Who Have Sex with Men.

Mild cases of KS have been reported in HIV-negative men who have sex with men.2 It is unclear what factors contribute to KS in this population.3

What are risk factors for Kaposi sarcoma?

In the United States, HIV infection is the main risk factor for KS.1 Racial/ethnic and gender risk factors reflect differences in HIV infection. HIV-related KS is 10-fold higher in men than women. It is higher in black and Hispanic persons than white and Asian persons.1

How is Kaposi sarcoma diagnosed?

Diagnosis often starts with a visit to the doctor about a concerning sign or symptom.2 The main sign of KS is a lesion on the skin or mouth. Lesions also can appear in locations such as the eyelid or anus. Lesions on internal organs can cause internal bleeding. For example, lesions on the lungs can cause you to cough up blood. Gastrointestinal lesions may cause black, tarry, or bloody stool, diarrhea, or constipation.

If your doctor suspects that a skin lesion is KS, she or he may take a tissue sample. A pathologist will study the sample under a microscope, looking for abnormal cells that indicate KS.

Other tests are needed to look for lesions on internal organs.2 If lesions are found, a tissue sample can be taken from the internal lesion. Chest x-ray may be done to look for KS in the lungs. Special videos cameras may be used to look for lesions in the lungs (bronchoscopy), upper gastrointestinal tract (endoscopy), small intestine (capsule endoscopy or double balloon endoscopy), or large intestine (colonoscopy).

What does Kaposi sarcoma look like?

KS lesions are red or purple, and they may be flat, raised, or bumpy.2,4 Usually, the lesions are painless at first, but may become open sores (ulcerate). They may develop on the skin, mucous membranes, or internal organs. The most common location for skin lesions is the face or legs.2 You may also notice lesions that form in the mouth, throat, or eyelid.2

What is the survival rate for Kaposi sarcoma?

As HIV treatment improves, so do KS survival rates. Currently, the overall 5-year survival rate is 73%.1

What are the treatments for Kaposi sarcoma?

The goal of treatment for KS is to reduce symptoms.3 Treatment may reduce the size of skin lesions or eliminate them altogether. Shrinking the lesions may reduce swelling and skin ulceration.3 Some treatments are given to reduce symptoms of lesions in the mucous membranes or internal organs. There are no data showing that treatment prolongs survival.

Local therapies used to treat KS lesions include:2,3

Because people with KS usually have a weakened immune system, systemic (whole body) treatment is challenging. For example, chemotherapy makes the immune system even weaker. However, with careful planning, chemotherapy can be used to treat KS.2 You may take chemotherapy medications until the lesions are stable, and then stop. The chemotherapy drugs used to treat KS include:2,5

  • Liposomal doxorubicin (approved for KS)
  • Paclitaxel (approved for KS)
  • Vinblastine (approved for palliative treatment of KS)
  • Gemcitabine
  • Vinorelbine
  • Bleomycin
  • Vincristine
  • Etoposide

The main chemotherapy drug for KS is liposomal doxorubicin. Doxorubicin is attached to tiny fat particles called liposomes. Because the liposomes prefer Kaposi sarcoma tissue over normal tissue, the drug builds up in the tumor.6 This spares some healthy tissue.6

Cytokineimmunotherapy with interferon-alfa was an early treatment for KS.3 Taking interferon-alfa gives your immune system a boost, helping it to fight cancer. Interferon-alfa works best for patients with no systemic symptoms, limited lymph node disease, and fairly good immune function.7 However, severe side effects limit the use of this treatment.2

How can I prevent Kaposi sarcoma?

HIV is a strong risk factor for Kaposi sarcoma. Taking steps to prevent HIV infection lowers your risk of developing KS. These steps may include:

  • Using safer-sex practices, such as consistent use of a condom.
  • Taking a daily pill for PrEP (pre-exposure prophylaxis), if you are at high risk of HIV infection. PrEP is a prescription medication; talk to your doctor about whether it is appropriate for you.
  • Using clean needles and syringes if you inject drugs, or getting help to stop injection drug use.

If you have HIV infection, taking your HIV medications reduces your risk of KS. The availability of HIV medications has reduced the number of new cases and deaths due to KS. New cases of KS are declining by 3.4% per year.1