Kaposi's sarcoma (KS) is a type of cancer. It causes growths, mainly under the skin, although they can grow in the lining of the mouth, nose, throat and other organs.

It differs from other cancers as it starts in several areas of the body at once. Most cancers start in one place and then spread.

KS causes lesions (abrasions) or tumours (growths). They most commonly appear on the skin as small, flat, coloured lesions that can be brown, blue, red or deep purple. Lesions can also develop on the internal organs. The organs which are most affected are:

• lymph nodes (part of the immune system),
• lungs, and
• digestive system, including the bowel, liver and spleen.

Types of Kaposi's sarcoma

There are four types of KS:

• HIV- or AIDS-related KS,
• classic KS,
• endemic or African KS, and
• transplant-related KS.

HIV- or AIDS-related KS

KS can develop in people whose immune system has been severely weakened by HIV or AIDS. It mostly affects gay men with HIV or AIDS. KS rarely affects women or straight men with HIV or AIDS. It is thought that this is because the virus that causes KS is spread during unprotected anal sex.

HIV- or AIDS-related KS used to be the most common complication affecting gay men living with HIV and was a leading cause of death. This is no longer the case due to anti-HIV medications, known as highly active antiretroviral therapy (HAART), that were developed in the 1990s.

Classic KS

Classic KS is a rare condition. It usually only affects men between 50 and 70 years of age who are of Mediterranean or eastern European descent. It is thought that people who develop classic KS were born with a pre-existing genetic vulnerability to the virus that causes it.

Endemic or African KS

Endemic KS is common in parts of Africa and is one of the most widespread types of cancer in that region. As with classic KS, endemic KS is thought to develop due to a pre-existing genetic vulnerability to the virus that causes it.

The situation has recently been complicated by the HIV epidemic in Africa, and many people may now be more vulnerable to the virus because of a weakened immune system due to HIV or AIDS.

Transplant-related KS

Transplant-related KS is an uncommon complication of organ transplants. In England, an estimated 0.5% of people who have an organ transplant develop KS.

People who have had an organ transplant usually take medication to weaken their immune system (immunosuppressants) to prevent their body rejecting the new organ. The weakening of their immune system makes them more vulnerable to the virus that cause KS.

Outlook

HIV- or AIDS-related KS

The outlook for HIV- or AIDS-related KS is variable and depends on a person's age and how weakened their immune system is. 

In an older person with a weakened immune system, the cancer often spreads aggressively to other parts of the body (metastasis).

The estimated survival rate for HIV- or AIDS-related KS is five years, although many people live a lot longer. The survival rate is expected to improve as medication for treating HIV improves.

Classic KS

The outlook for classic KS is good. The cancer tends to spread slowly and does not usually spread to other parts of the body. As classic KS primarily affects older people, those with the condition often die from other causes before the cancer progresses to a more serious stage.

Endemic KS

The outlook for endemic KS is poor, not least because access to treatment such as chemotherapy is often limited in parts of the world where endemic KS is widespread.

Transplant-related KS

The outlook for transplant-related KS is generally good because the condition can usually be successfully treated by reducing or stopping a person's course of immunosuppressants. However, this carries the risk that their body will reject the donated organ.

Lesions

A lesion is an abnormal change in an organ or body tissue because of injury or disease.

Lymph nodes

Lymph nodes are small oval tissues that remove unwanted bacteria and particles from the body.

Immune system

This is the body's defence system, which helps protect it from disease, bacteria and viruses.

Lungs

Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.

Liver

The liver is the largest organ in the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and change food into energy.

Recipients

A recipient is a person that receives donated blood, tissue or an organ from another person.

Radiotherapy

In radiotherapy, X-rays are used to treat disease, especially cancer.

Chemotherapy

Chemotherapy is the treatment of an illness or disease with a chemical substance. It is used in the treatment of cancer.