Kaposi sarcoma (KS) is a rare cancer that starts in cells that line the lymph or blood vessels. It differs from other sarcomas because it can appear in several parts of the body at the same time.
KS usually develops on or under the skin. It may also happen in lymph nodes or in the layers of tissue that line the mouth, nose, throat or anus. KS can also develop in the lungs or parts of the gastrointestinal (GI) tract.
These are the main risk factors for KS:
- infection with human herpesvirus 8, or HHV-8 (also called Kaposi sarcoma-associated herpesvirus, or KSHV) – a virus found in the tumours of people with AIDS-related KS
- having a weakened immune system (immunosuppression)
Types of Kaposi sarcoma
There are 4 main types of KS.
AIDS-related Kaposi sarcoma
AIDS-related KS is also called epidemic KS. It is the most common type of KS. It develops in people infected with HIV (human immunodeficiency virus). HIV is the virus that causes AIDS (acquired immune deficiency syndrome). It damages the immune system cells so the body can’t fight infections and illnesses. As the immune system becomes weaker, the risk of developing KS increases. If a person infected with HIV develops KS, they are also diagnosed with AIDS.
AIDS-related KS can develop in many different parts of the body, including the skin, mouth, lymph nodes, GI tract, lung, liver and spleen. AIDS-related KS eventually spreads throughout the body.
Classic Kaposi sarcoma
Classic KS is not common. It mainly happens in older people of Mediterranean, Middle Eastern and eastern European ancestry. It is more common in men than in women.
Classic KS grows slowly. It is usually found only in the skin, particularly on the lower legs, ankles and soles of the feet. But it can spread to the GI tract, lymph nodes or other organs. Some people with classic KS develop a second cancer, most often non-Hodgkin lymphoma.
Transplant-related Kaposi sarcoma
Transplant-related KS is also called iatrogenic KS. It happens in people who have a weakened immune system after an organ transplant. People who have had an organ transplant usually need to take drugs that weaken the immune system (called immunosuppressive therapy) to reduce the risk that the body will reject the donated organ. This increases the risk of developing infection with HHV-8.
Transplant-related KS often affects only the skin, but it can also spread to mucous membranes or other organs.
African Kaposi sarcoma
African KS is also called endemic KS. It is found in parts of Africa near the equator. It is more common in young adult males.
African KS can grow slowly like classic KS, but there is also a form that grows very quickly (is aggressive). Along with causing skin tumours, African KS can grow into tissues under the skin (subcutaneous tissue) and into bone.
One form of African KS happens commonly in young children. It develops in lymph nodes and other organs. It tends to have a very poor prognosis.
KS usually appears on the skin first. The signs or symptoms of KS include:
- growths, patches or bumps on the skin that are often red, purple or brown
- patches or bumps in the mouth or throat
- swollen feet and ankles that can be painful
- enlarged lymph nodes
- GI bleeding, such as blood in the stool
- pain in the abdomen
- difficulty breathing
- weight loss
Diagnosing KS usually begins with a visit to your family doctor. Your doctor will ask you about any symptoms you have and will do a physical exam. Based on this information, your doctor may refer you to a specialist or order tests to check for KS or other health problems. These tests may be done:
- biopsy, such as a punch biopsy or surgical biopsy
- chest x-ray
- CT scan
- endoscopy, such as a colonoscopy or bronchoscopy
Stages and risk groups
Staging describes or classifies a cancer based on how much cancer is in the body and where it is when first diagnosed. This is often called the extent of cancer. Your healthcare team uses the stage to plan treatment and estimate the outcome (your prognosis).
There is a staging system for AIDS-related KS developed by the AIDS Clinical Trials Group. It is based on 3 factors:
- where KS is in the body – only in the skin and lymph nodes or widespread throughout the body
- health of the immune system – a high or low number of CD4 cells (a type of lymphocyte) in the blood
- how much illness is in the body – having or not having symptoms and illness throughout the body, such as fever, night sweats or infections
Doctors then classify the KS as good risk or poor risk based on these factors.
KS is different than other soft tissue sarcomas, so it is treated differently. When deciding which treatments to offer for a KS, your healthcare team will consider:
- the type of KS
- if the KS is only in a certain area (local disease) or in many parts of the body (widespread disease)
- how well your immune system is working
- your general health
Treatments for infections and immunosuppression
An important part of treatment for KS is to treat any infections and manage immunosuppression.
Combined antiretroviral treatment (cART) is a combination of drugs used to treat HIV. It is also the first treatment for AIDS-related KS. Sometimes cART may be the only treatment needed or it can be combined with chemotherapy.
Stopping immunosuppressive therapy may be the first step in treating transplant-related KS. Transplant-related KS sometimes improves if immunosuppressant drugs are stopped or the dose is lowered, but this can increase the risk of organ rejection.
Antibiotics are used to treat and prevent infections with bacteria.
Surgery can be used to remove small areas of KS on the skin, especially when the KS is classified as a good risk. The following types of surgery may be used.
Surgical excision removes the cancer along with some normal tissue around it.
Curettage and electrodesiccation uses a sharp tool (called a curette) to scrape the cancer. Then the area is treated with an electrical current to destroy any remaining cancer cells.
Cryosurgery uses extreme cold to freeze and destroy tissue. Find out more about cryosurgery.
External radiation therapy (also called external beam radiation therapy) uses a machine to direct a beam of radiation to the area of skin and a small amount of nearby tissue. It may be used to treat one or a few skin tumours in a specific area. In some cases, it may also be used to control more widespread disease.
Find out more about radiation therapy.
Topical therapy uses a cream or gel to put drugs directly on the skin. Alitretinoin (Panretin) is a topical therapy that may be used for AIDS-related KS of the skin.
Chemotherapy uses anticancer (cytotoxic) drugs to destroy cancer cells. It is usually given as a systemic therapy, which means that the drugs travel through the blood to reach and destroy cancer cells all over the body. Chemotherapy drugs used alone or in combination for KS include:
- pegylated liposomal doxorubicin (Caelyx)
- paclitaxel (Taxol)
- docetaxel (Taxotere)
- vinorelbine (Navelbine)
- gemcitabine (Gemzar)
- bleomycin (Blenoxane)
- etoposide (Vepesid, VP-16)
- vincristine (Oncovin)
A small amount of chemotherapy drug may be injected directly into the skin tumour to kill the cancer cells (called intralesional chemotherapy). Vinblastine is used most often.
Find out more about chemotherapy.
Immunotherapy uses drugs to help the body’s immune system fight cancer cells. It is sometimes used alone or in combination with chemotherapy for AIDS-related KS. Immunotherapy drugs that may be used include interferon alfa-2a, interferon alfa-2b and interleukin-12.
Find out more about immunotherapy.
Targeted therapy uses drugs to target specific molecules (such as proteins) on or inside cancer cells to stop the growth and spread of cancer and limit harm to normal cells. It is used in some people with AIDS-related KS. Targeted therapy drugs used include imatinib (Gleevec) and bevacizumab (Avastin).
Find out more about targeted therapy.
For more detailed information on specific drugs, go to sources of drug information.
Referring to or having to do with the digestive organs.
The gastrointestinal (GI) tract, or digestive tract, includes the mouth, pharynx (throat), esophagus, stomach, small intestine and large intestine.
A disease caused by the human immunodeficiency virus (HIV) in which lymphocytes (a type of white blood cell that fights germs, foreign substances or cancer cells) are destroyed and the body cannot protect itself from infection.
People with AIDS are at an increased risk for developing certain cancers, including Kaposi sarcoma.
Also called acquired immunodeficiency syndrome.
The thin, moist layer of tissue that lines some organs and body cavities, including the nose, mouth, lungs, airways, vagina and gastrointestinal (GI) tract.
Glands in the mucous membrane make mucus (a thick, slippery fluid).
Also called mucosa.
A type of white blood cell that fights viruses, bacteria, foreign substances or abnormal cells (including cancer cells).
The 3 types of lymphocytes are B cells, T cells and natural killer (NK) cells.
Suppression of the body’s immune system so it is less able to fight infections or diseases.
Immunosuppression can be caused by certain diseases, such as AIDS or lymphoma. It may also be a side effect of certain chemotherapy drugs. Doctors may also deliberately suppress the immune system before organ or stem cell transplants to prevent rejection.
Also called immunocompromised.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
Taking action against all cancers
The latest Canadian Cancer Statistics report found that of all newly diagnosed cancers in 2017, half are expected to be lung, colorectal, breast and prostate cancers. Learn what you can do to reduce the burden of cancer.