Kaposi’s sarcoma (KS)

Summary

Kaposi’s sarcoma (KS) is a cancer that causes abnormal patches to grow on the skin or inside the body. While KS on the skin is not life-threatening, when the disease affects the internal organs, it can cause serious problems and, in some cases, be life-threatening. The disease occurs almost only in people with very weak immune systems. Anti-HIV drugs and a variety of local and systemic treatments can be used to treat KS in people living with HIV.

KS used to be the cancer that most commonly affected people living with HIV; however, since the introduction of more effective anti-HIV drugs in the mid-1990s, the number of HIV-positive people who are diagnosed with KS has dropped dramatically.

What is KS?

KS is caused by a herpes virus called human herpes virus 8 (or HHV8). KS is a form of cancer that most often affects the skin. KS on the skin is characterized by the abnormal growth of blood vessels, which appear as spots, also called lesions. These may look like bruises on a person’s skin. KS can also develop in mucosal tissue—for example, the lining of the mouth or the nose; in the lymph nodes; or in internal organs, such as the bowel, lungs, liver or stomach. Whereas other kinds of cancer typically develop in one part of the body and can then spread to others, KS can develop in different parts of the body at once.

Who is at risk for KS?

KS primarily affects people living with HIV who have very weakened immune systems. People living with HIV whose CD4 count is below 200 are at greatest risk of KS and are more likely to develop more serious forms of the disease.

There have been cases where people whose HIV was under control were diagnosed with the disease; however, such cases are rare and the KS in people with stronger immune systems tends to be very mild and not pose serious dangers to their health.

Although women can and do develop KS, men are approximately eight times more likely to do so.

In addition to people living with HIV, groups at risk for KS include HIV-negative gay men and men who have sex with men, women who have sex with bisexual men, people who take medications that suppress the immune system (such as corticosteroids), and communities in parts of sub-Saharan Africa.

Symptoms

KS on the skin causes lesions that

• can appear in a wide range of colours: from pink to red to purple on light-skinned people, and from dark purple to brown to black on dark-skinned people
• can range in size from a few millimetres to a few centimetres in diameter
• may be raised or flat
• are usually painless and don’t itch

At first, these lesions may be small and may cause no problems except for concern about their appearance. KS lesions may change very little from month to month or they may spread and become raised or lumpy. Lesions on the feet and legs can make it difficult to walk.

KS in the mouth can cause flat lesions and may make it difficult to eat, swallow and speak. However, some people who develop KS in the mouth experience no symptoms at all.

Although KS in the digestive tract usually causes no symptoms, it can cause pain, internal bleeding and blockages.

KS in the lymph nodes can potentially cause swelling of the limbs, face or scrotum.

KS in the lungs can block a person’s airways and lead to fluid buildup, which may cause coughing and difficulty breathing. This is the most serious and life-threatening form of KS.

Diagnosis

Some doctors diagnose KS on the skin by simply examining a person’s body. KS skin lesions tend to be flat and, unlike a bruise, when you push on one, it does not lose its colour. A biopsy of the skin is required to confirm the diagnosis. A biopsy involves removing a small piece of the affected tissue. That sample is then sent to a lab so it can be examined under a microscope.

To diagnose KS of the internal organs, an endoscopy or bronchoscopy may be used. A thin, flexible tube with a viewing device that allows a doctor to see the inside of organs may be inserted down the esophagus, stomach and small intestine, or into the rectum and colon (this procedure is called an endoscopy); or into the windpipe and lungs (bronchoscopy). During the procedure, samples of tissue may be removed for analysis. KS in the rectum can sometimes be diagnosed by digital exam. A digital exam is a test used to examine the lower rectum—a doctor inserts a gloved finger into the rectum to feel for abnormalities. Chest x-rays may be taken to diagnose KS in the lungs.

Treatment

After a person living with HIV is diagnosed with KS, they should start taking a combination of anti-HIV drugs (antiretroviral therapy or ART) immediately if they aren’t already on ART. This will help boost the immune system and treat the KS. If the anti-HIV drugs don’t make the KS disappear, they will likely cause the symptoms to improve. At the same time, these drugs can help prevent a second infection from developing.

There are also various treatments used to treat KS specifically. Whether or not one of these treatments is needed and which type of treatment is most suitable depends on the location, size and extent of the KS.

• For KS on the skin, treatments include medicated gels and creams, surgery, radiation therapy, and other procedures used to remove the lesions. If the KS on your skin is widespread, your doctor may recommend anti-cancer drugs (chemotherapy) in addition to anti-HIV drugs. If you have only a few small lesions, you may not require any additional treatment.
• KS in the internal organs may be treated with chemotherapy in addition to anti-HIV drugs.

Side effects of treatments

Local therapy

Local therapies, or therapies that treat a specific area (as opposed to systemic therapy), can cause pain, redness and swelling at the site of treatment. Some local treatments may also leave the area where the lesion was looking noticeably lighter or darker than the rest of the skin.

Systemic therapy

Chemotherapy drugs can cause many side effects, including damage to bone marrow. Bone marrow makes white blood cells that help fight off infections. Damage to the bone marrow weakens the immune system and may put some people at risk of developing opportunistic infections—that is, potentially serious infections that take advantage of a weakened immune system and do not normally affect healthy people. Additional side effects of chemotherapy may include hair loss, nausea, vomiting, diarrhea and fever.

Prevention

If you are HIV-positive, the best way to prevent KS is to take anti-HIV drugs (antiretroviral therapy) to keep your immune system strong. There are currently no vaccines available to prevent a person from getting HHV8, the virus associated with KS.