Kaposi's sarcoma (KS) is a form of cancer affecting blood vessels. It causes widespread lesions on the skin, mucous membranes, or internal organs. It occurs most commonly in the gastrointestinal tract and lungs.

Cancer occurs when cells in the body divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissues and can spread to other parts of the body. A benign tumor does not invade or spread.

KS can be classified according to the population affected:

• Classic–usually affects men of Mediterranean descent

• Endemic–usually affects people living in equatorial Africa

• Transplant-related (Acquired)–affects people who have received an organ transplant

• AIDS-related (Epidemic)–affects people with AIDS

Causes

Now most cases of KS occur in people with AIDS. However, recent evidence shows a strong link between KS and a sexually transmitted virus, human herpes virus 8 (HHV8), in AIDS patients. The virus, in combination with an immune system suppressed by AIDS, probably accounts for most cases of KS. HHV8 also appears to be linked to classic and endemic KS.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Risk factors include:

• HIV infection

• Men who have sex with men, and women who have sex with bisexual men

• Drugs that suppress the immune system

Symptoms

The most common symptom is skin or mucus membrane lesions that:

• Appear as raised blotches or nodules

• Develop anywhere on the body

• Are purple, brown, red, or pink

• May cause swelling and pain

Other symptoms include:

• Internal bleeding (when lesions develop inside the body)

• Breathing problems (when lesions develop in the lungs)

Diagnosis

The doctor will ask about your symptoms and medical history and perform a physical exam. Initial diagnosis may be based on the presence of the skin lesions, if they exist. If there is unexplained bleeding, pain, or weight loss, your doctor may need to perform other tests (perhaps more invasive) to determine if you have KS.

Tests may include:

Biopsy–removal of a sample of tissue from a lesion to test for cancer cells

CT Scan–a type of x-ray that uses a computer to generate images of structures inside the body

Bronchoscopy–a thin, lighted tube inserted down the throat to examine the airways in the lungs

Endoscopy–a thin, lighted tube passed down the esophagus or up the rectum to examine the gastrointestinal tract

In the absence of skin or mucus membrane lesions, KS may be suspected if you have AIDS and your lymph nodes are swollen.

Treatment

Treatment depends on the type of Kaposi's sarcoma. Treatment of AIDS-related Kaposi's sarcoma does not cure the disease, but it can relieve pain.

Treatments include:

Surgery–surgical removal of KS lesions on the skin and mucus membranes may be done for symptomatic or cosmetic reasons. Surgery to remove internal lesions depends on their size, location, and associated symptoms. Because KS can bleed profusely after surgery, the surgeon will attempt to remove the entire lesions with a margin of normal tissue around it to reduce bleeding.

Radiation Therapy–the use of radiation to kill cancer cells. Indications are the same as for surgery. Generally, radiation therapy is delivered once or in divided doses over 2-3 weeks. The number of radiation treatments necessary will depend on the size and location of the KS lesion(s).

Antiretroviral Therapy–used to directly combat HIV and restore immune function in patients with AIDS. May be highly effective against KS in some patients.

Chemotherapy–the use of drugs to kill cancer cells. Chemotherapy may be given in many forms including: pill, injection, and via a catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells, but also some healthy cells. In some cases, chemotherapeutic agents can be injected directly into a KS lesion.

Biological Therapy–the use of medications or substances made by the body to increase or restore the body's natural defenses against cancer. Also called biological response modifier therapy.

Prevention

There are no guidelines for preventing classic, endemic, and transplant-related Kaposi's sarcoma.

To prevent AIDS-related Kaposi's sarcoma, take the following steps to minimize your exposure to HIV:

• Abstain from sex or use a male latex condom. This includes intercourse and any other sexual acts that result in the exchange of body fluids.

• Do not share needles for drug injection.

• Limit your number of sexual partners.

• Avoid sexual partners who are HIV infected or injection-drug users.

• Avoid receiving transfusion of unscreened blood products.

• If you are a healthcare worker:

• • Wear latex gloves and facial masks during all procedures.

• • Carefully handle and properly dispose of needles.

• • Carefully follow universal precautions (a detailed list of how to handle such things as needles and other biohazard materials).

• If you live in a household with an HIV-infected person:

• • Wear latex gloves if handling HIV-infected body fluids.

• • Cover all cuts and sores (yours and the HIV-infected person's) with bandages.

• • Do not share any personal hygiene items (razors, toothbrushes, etc.).

• • Carefully handle and properly dispose of needles used for medication.

RESOURCES:

American Cancer Society
http://www.cancer.org

International Association of Physicians in AIDS Care
http://www.iapac.org

National Cancer Institute
http://www.cancer.gov

References:

American Cancer Society website. Available at: http://www.cancer.org.

The Merck Manual of Medical Information—Home Edition. Simon and Schuster, Inc.; 2000.

National Cancer Institute website. Available at: http://www.cancer.gov/.