Kaposi sarcoma (KS) starts in cells that line the lymph or blood vessels. It is named after the doctor who first described this type of tumour. KS is a rare tumour. 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 occur in lymph nodes or in the mucous membranes (thin, moist layers of tissue that make mucus) that line the mouth, nose, throat or anus. KS can also develop in the lungs or parts of the gastrointestinal (GI) tract.
Kaposi sarcoma is a rare type of sarcoma. There are different types of KS. The classic type usually occurs in older people, often of Russian, Jewish, Italian or African ancestry. The AIDS-related type occurs in people infected with HIV or AIDS.
The main risk factors for KS are infection with Human herpes virus 8 (HHV-8) and a weakened immune system.
HHV-8 is also called Kaposi sarcoma herpes virus (KSHV). It is a virus found in the tumours of all people with AIDS-related KS. The virus can be spread through sexual contact and infects cells that line blood and lymph vessels. The infection can turn the normal, healthy cells into cancerous cells. Many people infected with HHV-8 do not get KS. Therefore, other factors are probably involved, including a weakened immune system or genetic factors.
People with a weakened immune system have a higher risk of developing KS. The immune system can be weakened by diseases like AIDS (acquired immunodeficiency syndrome), Castleman disease or hemolytic anemia. It can also be weakened by immune-suppressing drugs such as those taken after an organ transplant.
KS usually appears first on the skin. It can also develop on mucous membranes, such as those inside the mouth. KS can also appear in other parts of the body. The most common symptoms are discussed below.
KS usually appears as painless patches or bumps, which are called lesions. Lesions on the skin are usually purple in colour, but can range from brown to red to bluish. There may be a yellow-brown colour, or bruised appearance, around the tumours if blood cells in the area are leaking. They most often develop on the legs or face, but can also appear in other areas.
The lesions can develop quickly. There may be only one at first, but it is not uncommon for several lesions to appear at the same time. The bumps can grow together and form a larger tumour, or nodule.
Lesions in mouth or throat
Patches or bumps, called lesions, can also develop on mucous membranes in the mouth or throat.
Tumours in the lymph nodes can block the flow of lymph fluid and cause lymphedema. Lymphedema is a buildup of lymph fluid and swelling in some parts of the body, such as the legs or face. Lymphedema can cause the affected limb to feel heavy, uncomfortable or painful.
Sometimes tumours can occur in the lung and may block part of an airway and cause shortness of breath, unexplained cough or chest pain.
Gastrointestinal tract problems
Tumours in the gastrointestinal tract can cause nausea, vomiting, abdominal pain, diarrhea or bleeding from the rectum.
Some people with KS may feel perfectly well. Many others will have flu-like symptoms such as fatigue, fever, body aches and pain, and weight loss.
Diagnosing Kaposi sarcoma 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. This may include tests that examine the skin, lungs and gastrointestinal (GI) tract and may include:
Your doctor will take a health history of your symptoms, risk factors and all the medical events and problems you have had in the past. Your doctor will examine the size, shape, colour and other characteristics of any tumours. Your doctor will also feel lymph nodes in different parts of your body, including your neck, armpits and groin.
During a biopsy, such as a skin biopsy, the doctor removes tissues or cells from the body so they can be tested in a lab. The report from the lab will confirm whether or not cancer cells are present in the sample.
An x-ray uses small doses of radiation to make an image of the body’s structures on film. A chest x-ray may be done to check for KS in the lung.
A computed tomography (CT) scan uses special x-ray equipment to make 3-dimensional and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures.
A CT scan can show whether there are signs of KS in other parts of the body and can help diagnose KS in the lymph nodes.
Depending on your symptoms, your doctor may do different types of endoscopy to check for KS. It allows a doctor to look inside the body using a tube with a light and lens on the end. This tool is called an endoscope. The doctor uses the endoscope to look for tumours and remove samples of tissues.
If there are symptoms that KS is in the gastrointestinal tract, your doctor may do a gastroscopy or colonoscopy. If there are symptoms that KS is in the lungs, your doctor may do a bronchoscopy to look inside the windpipe, or trachea, and lungs.
There are 4 main types of KS.
AIDS-related (epidemic) Kaposi sarcoma
AIDS-related KS is the most common of the 4 types. It develops in people infected with HIV (human immunodeficiency virus). This virus destroys certain immune system cells so the body can’t fight infections. But HIV can be present in the body for a long time without causing physical problems, and people with HIV don’t necessarily have AIDS. AIDS occurs when the virus causes serious damage to the immune system and infections and other medical problems develop. Because the immune system becomes weaker with AIDS, the risk of developing KS increases.
AIDS-related KS tumours can occur on many different parts of the body. They may develop on the skin, particularly the feet, legs, face and genitals, and in the mouth. They can also affect the lymph nodes, gastrointestinal (GI) tract, lung, liver or spleen. AIDS-related KS eventually spreads throughout the body.
People with AIDS-related KS may have swollen lymph nodes and a fever. They may also lose weight.
AIDS-related KS has become less common. This is because awareness of how HIV is transmitted has improved and fewer people become infected. AIDS treatment has also improved. Highly active antiretroviral therapy (HAART) is a combination of anti-HIV drugs. It is used to treat HIV infection and reduces the risk of developing AIDS-related KS. HAART is also used as a treatment for KS.
Classic Kaposi sarcoma
Classic KS is very uncommon. It usually only occurs in older people of Mediterranean, Middle Eastern or Jewish ancestry. Classic KS is more common in men than in women. People who get classic KS come from areas where the KSHV is common. Classic KS tumours are usually found only in the skin, particularly on the lower legs, ankles and soles of the feet.
Classic KS is a slow-growing cancer that gradually gets worse over years. It can spread to the lungs, gastrointestinal tract and lymph nodes. Some people with classic KS develop a second cancer, most often a non-Hodgkin lymphoma (NHL).
Transplant-related Kaposi sarcoma
Transplant-related KS is also called immunosuppressed, acquired or iatrogenic KS. It occurs in people who have a weakened immune system after an organ transplant. People who have received an organ transplant often have to take drugs that suppress the immune system (immunosuppressant drugs) to reduce the risk that the body will reject the donated organ. This type of KS rarely occurs.
Transplant-related KS sometimes improves if immunosuppressant drugs are stopped or the dose is lowered, but this can increase the risk of organ rejection. Transplant-related KS often affects only the skin, but it can also spread to the mucous membranes or other organs.
African (endemic) Kaposi sarcoma
African KS is found in parts of Africa, particularly near the equator. It can affect men, women and children of all ages, although it is more common in young adult males.
African KS can be very aggressive. It develops more quickly than classic KS. Along with causing skin tumours, African KS can also spread to the bone.
One form of African KS occurs commonly in young children. It does not affect the skin but spreads to the lymph nodes and other organs such as the heart. This type of KS can quickly become life-threatening.
Staging is a way of describing or classifying a cancer based on the extent, or amount, of cancer in the body. In 1988 a group of researchers known as the AIDS Clinical Trials Group (ACTG) proposed a staging classification system for AIDS-related Kaposi sarcoma called the TIS system. This system considers 3 factors:
- T describes the extent of the tumour.
- I describes the status of the immune system. This is measured by the number of certain cells (CD4 cells) present in the blood.
- S describes the extent of disease within the body, or systemic illness.
Under each of these major factors, there are 2 subgroups. These subgroups describe the cancer as either a good risk (0) or poor risk (1), based on T, I and S. Poor risk Kaposi sarcoma has a poorer prognosis than and may not respond to treatment as well as good risk cancer. Doctors can use the overall risk group to plan treatment.
|Good risk (risk level 0)||Poor risk (risk level 1)|
One or more of the following apply:
One or more of the following apply:
KS in the lungs is a particularly poor risk.
Immune system (I)
CD4 cell count is 150 or more cells per cubic millimetre
CD4 cell count is lower than 150 cells per cubic mm
Systemic illness (S)
No systemic illness present.
All of the following apply:
Systemic illness present.
One or more of the following apply:
B symptoms include fever, night sweats, weight loss and diarrhea.
The Karnofsky performance score is a standard measure of a person’s ability to perform ordinary tasks and carry out daily activities. It is used to assess prognosis, to monitor changes in a person’s ability to function or to decide if a person is suitable for a clinical trial. The person’s performance status is given a score out of 100. The higher the score, the better able a person is to carry out daily activities.
Overall risk group
Your healthcare team will assess all of these to assign your cancer an overall risk group. The immune system status is not as important in determining the overall risk. Good risk includes T0 S0, T1 S0 or T0 S1 and poor risk is described as T1 S1.
KS behaves differently than other soft tissue sarcomas, so it is treated differently. Sometimes 2 or more different treatments are used together. Treatment options depend on:
- the type of KS
- the number, location and size of the lesions
- how well the person’s immune system is working
- the person’s general health
The most important part of treating KS is addressing a weakened immune system as well as any related infections. The focus of this treatment is different for the different types of KS. Any bacterial infection can make KS tumours worse, so these infections are treated promptly, usually with a course of antibiotics.
- People with AIDS will receive anti-HIV drugs or HAART. Sometimes HAART may be the only treatment needed for the KS.
- Doctors may lower the dose or change the immunosuppressant drugs people take after an organ transplant.
- People who have the KSHV may be given antiviral medicines to help prevent new tumours from developing.
Mild cases of KS are usually considered good risk. They may not need to be treated, or could be treated with local therapy. This type of treatment may be used to treat a few skin tumours in one area, especially if they are very visible or unsightly.
Local therapy treats specific tumours. It doesn’t treat tumours elsewhere on the body and can’t prevent new lesions from developing.
A gel or ointment is applied directly to the tumour 2–4 times a day. It is given for a period of 2 or more months until the tumour is gone. Alitretinoin (Panretin) is one drug that may be used in topical treatment.
Liquid nitrogen is applied directly to the tumour to freeze it. The area is allowed to thaw and then is refrozen. This cycle may have to be repeated a few times until the tumour is gone.
A small amount of chemotherapy drug is injected directly into the tumour to kill the cancer cells. Vinblastine (Velbe) is commonly used in intralesional chemotherapy for KS.
With phyotodynamic therapy, a drug that makes cells sensitive to light is injected into a vein. This drug builds up in cancer cells rather than normal healthy cells. After allowing time for the drug to build up in the cancer cells, they are exposed to light. The light activates the drug, which then kills the cancer cells.
Radiation therapy uses high-energy rays or particles to destroy cancer cells. External beam radiation therapy is sometimes used as the main treatment for KS, especially if there are a few unsightly tumours or if they are painful.
Surgery removes the tumour and any tissue that has been affected by cancer. Surgery is rarely used to treat KS, but it may be an option to treat some small surface tumours.
Local excision cuts out tumours in the skin. The doctor also removes a small amount of normal tissue around the tumour, called the margin.
Curettage and electrodessication uses a special instrument, called a curette, to scrape off the tumour. The area is then treated with an electric current to destroy any cancer cells left behind and to control bleeding. This procedure often needs to be repeated a few times.
Photon radiation, which is a type of external beam radiation therapy, may be used to treat KS tumours in the mouth or throat.
KS that is more widespread or has spread to other organs may be treated with systemic therapy. This type of treatment travels through the bloodstream to reach cancer cells all over the body.
Chemotherapy uses anticancer, or cytotoxic, drugs to stop cancer cells from growing and spreading. Some chemotherapy drugs can be wrapped in a fatty coating called liposome. The liposome helps the drug enter the KS tumours and allows it to be released slowly. This is called liposomal chemotherapy. In some treatment centres, it has become the treatment of choice for KS. The 2 liposomal forms of chemotherapy drugs that are used to treat KS are:
- liposomal doxorubicin (Myocet)
- liposomal daunorubicin (DaunoXome)
Other chemotherapy drugs that may be used to treat KS include:
- paclitaxel (Taxol)
- vinorelbine (Navelbine)
- gemcitabine (Gemzar)
- bleomycin (Blenoxane)
- etoposide (Vepesid, VP-16)
- vinblastine (Velbe)
- vincristine (Oncovin)
For more detailed information on specific drugs, go to sources of drug information.
Biological therapy uses natural or artificial substances to strengthen the body’s immune system to fight cancer or to lessen the side effects of treatment. It is sometimes called immunotherapy. Biological therapy drugs like interferon alfa (Intron A, Wellferon) may be used to treat KS. However, biological therapy is not often used because it causes numerous side effects and doesn’t work well in many people with AIDS.
Different types of treatment are used to treat the different types of KS.
AIDS-related (epidemic) KS
AIDS-related KS is best treated with HAART, including a protease inhibitor. Protease inhibitors are anti-HIV drugs that block protease, a protein HIV needs to make copies of itself. Other treatment options for AIDS-related KS may include:
- radiation therapy
- biological therapy
Treatment options for single skin tumours may include radiation therapy or surgery.
Treatment options for skin tumours spread over many parts of the body may include radiation therapy or chemotherapy.
Treatment options for classic KS that affects lymph nodes, the lung or the gastrointestinal tract may include chemotherapy or radiation therapy. Radiation therapy is sometimes given in addition to chemotherapy.
Transplant-related (immunosuppressed, acquired or iatrogenic) KS
Transplant-related KS may be treated by stopping or lowering the dose of immunosuppressant drugs. This approach may put the transplanted organ at risk of rejection. People with transplants should discuss the risks and benefits of this approach with their doctor.
This type of KS may also be treated with radiation therapy. Chemotherapy is also sometimes used.
African (endemic) KS
African KS is often treated with chemotherapy or radiation therapy. However, these treatments are rarely available in developing countries. This means that many people with African KS go untreated.
Recurrent KS means that the cancer has come back after it has been treated. It may recur in the skin or it may recur in another part of the body.
Treatment options for recurrent KS depend on the type of KS, the person’s overall health and prior treatment.
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.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
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