Kaposi sarcoma (KS) is a cancer that develops from the cells that line lymph or blood vessels. It usually appears as tumors on the skin or on mucosal surfaces such as inside the mouth, but these tumors can also develop in other parts of the body, such as in the lymph nodes (bean-sized collections of immune cells throughout the body), the lungs, or digestive tract.
The abnormal cells of KS form purple, red, or brown blotches or tumors on the skin. These affected areas are called lesions. The skin lesions of KS most often show on the legs or face. They may look bad, but they usually cause no symptoms. Some lesions on the legs or in the groin area may cause the legs and feet to swell painfully.
KS can cause serious problems or even become life threatening when the lesions are in the lungs, liver, or digestive tract. KS in the digestive tract, for example, can cause bleeding, while tumors in the lungs may cause trouble breathing.
Types of Kaposi sarcoma
There are four different types of KS defined by the different populations it develops in, but the changes within the KS cells are very similar.
Epidemic (AIDS-associated) Kaposi sarcoma
The most common type of KS in the United States is epidemic or AIDS-associated KS. This type of KS develops in people who are infected with HIV, the virus that causes AIDS.
HIV stands for human immunodeficiency virus. A person infected with HIV (someone who is HIV-positive) does not necessarily have AIDS, but the virus can be present in the body for a long time, often many years, before causing major illness. The disease known as AIDS begins when the virus has seriously damaged a person's immune system, which means they can get certain types of infections (such as Kaposi sarcoma--associated herpesvirus, KSHV) or other medical complications, including KS.
KS is considered an AIDS defining illness. This means that when KS occurs in someone infected with HIV, that person officially has AIDS (and is not just HIV-positive).
In the United States, treating HIV infection with highly active antiretroviral therapy (HAART) has resulted in fewer cases of AIDS-associated KS. Still, some patients can develop KS in the first few months of HAART treatment.
For most patients with HIV, HAART can often keep advanced KS from developing. Still, KS can occur in people whose HIV is well controlled with HAART. Even if KS develops, it is still important to continue HAART.
In areas of the world where it is not easy to get HAART, KS in AIDS patients can advance quickly.
Classic (Mediterranean) Kaposi sarcoma
Classic KS occurs mainly in older people of Mediterranean, Eastern European, and Middle Eastern heritage. Classic KS is more common in men than in women. People typically have one or more lesions on the legs, ankles, or the soles of their feet. Compared to other types of KS, the lesions in this type do not grow as quickly, and new lesions do not develop as often. The immune system of people with classic KS is not as weak as it is in those who have epidemic KS, but it may be weaker than normal. Getting older can naturally weaken the immune system a little. When this occurs, people who already have a KSHV (Kaposi sarcoma--associated herpesvirus) infection are more likely to develop KS.
Endemic (African) Kaposi sarcoma
Endemic KS occurs in people living in Equatorial Africa and is sometimes called African KS. Kaposi sarcoma--associated herpesvirus (KSHV) infection is much more common in Africa than in other parts of the world, so the risk of KS is higher. Other factors in Africa that weaken the immune system (such as malaria, other chronic infections, and malnutrition) also probably contribute to the development of KS, since the disease affects a broader group of people that includes children and women. Endemic KS tends to occur in younger people (usually under age 40). Rarely a more aggressive form of endemic KS is seen in children before puberty. This type usually affects lymph nodes and other organs and can progress quickly.
Endemic KS used to be the most common type of KS in Africa. Then, as AIDS became more common in Africa, the epidemic type became more common.
Iatrogenic (transplant-related) Kaposi sarcoma
When KS develops in people whose immune systems have been suppressed after an organ transplant, it is called iatrogenic, or transplant-related KS. Most transplant patients need to take drugs to keep their immune system from rejecting (attacking) the new organ. But by weakening the body’s immune system, these drugs increase the chance that someone infected with KSHV (Kaposi sarcoma--associated herpesvirus) will develop KS. Stopping the immune-suppressing drugs or lowering their dose often makes KS lesions go away or get smaller.
Kaposi sarcoma is always caused by an infection with a virus called human herpesvirus 8, which is also known as Kaposi sarcoma-associated herpesvirus (KSHV). The virus, which is in the same family as Epstein-Barr virus, is rare in the United States. In fact, less than 1 percent of the general U.S. population is a carrier. The virus and the tumor are much more common in some other parts of the world.
How the virus is initially acquired and spread is poorly understood, but scientists have identified four distinct populations that represent nearly all cases of the disease. There is some evidence within those populations as to how KSHV is acquired and what causes some carriers to develop Kaposi sarcoma.
What are the risk factors for Kaposi sarcoma?
You must already be infected with Kaposi sarcoma-associated herpesvirus (KSHV) to develop Kaposi sarcoma. However, most people who have the virus will never get Kaposi sarcoma. The cancer is usually triggered by a weakened immune system in people who are HIV-positive, who have received an organ transplant or whose immune systems are weakened for other reasons, including age.
What are the types of Kaposi sarcoma?
Kaposi sarcoma occurs in four different settings. The approach to treatment depends in part on the setting in which the tumor occurs..
Epidemic (AIDS-Related) Kaposi Sarcoma
In the United States, most cases of Kaposi sarcoma are related to HIV. HIV only leads to the development of Kaposi sarcoma in patients who are also KSHV infected.
Among HIV-positive individuals, it appears that men who have sex with other men are more likely to get Kaposi sarcoma, probably because KSHV is more common in this population. While experts presume that there is some sexual transmission of the virus, it is generally detected in saliva rather than semen.
During the AIDS epidemic, cases of Kaposi sarcoma grew drastically in the U.S., reaching more than 20 times the pre-epidemic numbers, according to the American Cancer Society. At the worst point, the incidence of disease was 47 per cases per year for every 1 million people. Individuals with HIV had a 50 percent chance of developing the disease.
Since then, Kaposi sarcoma has become less common, yielding about 6 cases per 1 million people each year. Antiretroviral treatment in HIV-positive patients has helped control and prevent the disease.
Classic (Mediterranean) Kaposi Sarcoma
Classic Kaposi sarcoma mainly occurs in older men of Mediterranean, Middle Eastern and Eastern European descent. These areas of the world have a much greater incidence of KSHV. While the reasons aren’t clearly understood, some evidence indicates that populations with high rates of KSHV likely acquired the virus in childhood, possibly through saliva transmission from mother to child.
As in other types of Kaposi sarcoma, experts believe that classic Kaposi tumors emerge as a result of a compromised immune system. Although these men may have carried the virus their entire lives, the cancer develops in the setting of a natural, age-related decline in immune function.
Endemic (African) Kaposi Sarcoma
In some areas of Equatorial Africa, a high percentage of the population may be infected with KSHV and therefore have a greater risk of developing Kaposi sarcoma. Once again, medical experts think that the virus is being spread mostly through saliva transmission from mother to child. Women and children are also being affected. Why the tumor develops in young boys whereas classic KS occurs mainly in old men isn’t known.
Transplant-Related Kaposi Sarcoma
Most patients receiving an organ or bone marrow transplant must take immunosuppressant drugs to keep their immune system from attacking the transplanted organ. But if an immunosuppressed transplant patient is already infected with KSHV, they have the potential to develop Kaposi sarcoma. Getting a transplant in a country where KSHV is more common (e.g., Italy or Saudi Arabia) further increases risk as the virus may be transmitted with the organ transplant.
What are the symptoms of Kaposi sarcoma?
Kaposi sarcoma symptoms include the following:
- Lesions on the skin. The first signs of Kaposi are usually cancerous lesions (spots) on the skin that are purple, red or brown and can appear flat or raised. These may appear in just one area, or they can show up in many areas. Often they are disfiguring. Common locations for lesions are the feet, legs and face.
- Lesions on mucous membranes. Lesions can also occur in the mouth, anus or elsewhere in the gastroinstestinal tract.
- Lesions inside the body. When lesions form inside the lungs, breathing can be restricted or the patient may cough up blood. Inside the GI tract, lesions can cause pain and bleeding, which may eventually lead to anemia.
- Lymph nodes. Involvement of lymph nodes, particularly in the groin can be associated with painful swelling in the legs.
How is Kaposi sarcoma diagnosed?
The disease has become so rare in the United States that not every doctor has seen it. Its rarity can lead to patients being seen by multiple doctors before getting a diagnosis. As with all cancers, early diagnosis can improve outcomes and lessen the risk of the disease spreading to other organs.
If you have signs of Kaposi sarcoma, a doctor will do a physical examination of your skin, mouth and rectum. The doctor will also check your lymph nodes.
- Skin biopsy. During this procedure, small pieces of tissue will be removed from the lesion(s). A pathologist will examine the samples in a lab to confirm the presence of Kaposi sarcoma.
- Chest X-ray. Since Kaposi sarcoma commonly spreads to the lungs, most patients will receive a chest X-ray. This noninvasive test may be used even if there appears to be no lung involvement.
- Bronchoscopy. If the chest X-ray shows an abnormality, or if you’re coughing up blood or having breathing problems, your doctor may order a bronchoscopy to look at your trachea and airways in greater detail.
- Endoscopy. An upper endoscopy and/or colonoscopy may be required if you have blood in the stool, abdominal pain or anemia.
In the past, it was much more common for patients with Kaposi sarcoma to have more advanced stages of disease. Today, only about 20 percent of patients have tumors beyond their skin or lymph nodes. This decrease in advanced disease has largely resulted from the success of antiretroviral therapies.
A new Kaposi sarcoma diagnosis can be scary and cause you to ask many questions. Learning everything you can about your cancer and its treatment options can help you feel less afraid. It will also make it easier for you to work with your health care team to make the best treatment decisions.
Working with Your Health Care Team
Your health care team may include the following:
- Dermatologist. This is a doctor who specializes in treating skin diseases.
- Infectious disease specialist. This is a doctor who treats infectious diseases such as AIDS.
- Medical oncologist. This is a doctor who specializes in treating cancer with medicines such as chemotherapy.
- Radiation oncologist. This is a doctor who specializes in treating cancer with radiation.
Many other health care professionals will be part of your team as well. They will help you by:
- Answering your questions
- Guiding you through tests and explaining your test results
- Helping you make treatment decisions
- Providing support during treatment
- Explaining your follow-up care plan
Because Kaposi sarcoma is rare, it’s helpful to receive care from a cancer center with experts who have experience treating this disease.
Coping with cancer can be very stressful. Talk with your health care team about referring you to a counselor for emotional support. You may also want to ask your health care team about joining a local or online support group. These groups are designed to help patients with Kaposi sarcoma share coping strategies.
What is the treatment for Kaposi sarcoma?
KSHV, the virus that causes Kaposi, cannot be treated. Once you contract KSHV, you will always have it. Treatment for Kaposi sarcoma is focused on managing symptoms and treating the cancer. The best approach will depend on your specific diagnosis and the extent of the disease.
Experts advise against regarding the disease as localized, even if it physically appears to be so. It should be treated with the assumption that it has spread beyond any visible signs.
The following treatment strategies may be used for patients with Kaposi sarcoma:
- Improving immune system function.The most effective and important therapy for patients with Kaposi sarcoma is addressing the immune deficiency that may allow the cancer to grow.
For AIDS patients, the same antiretroviral therapy used for AIDS may be all that’s needed to treat Kaposi sarcoma. For transplant recipients, changing or decreasing the dosage of immunosuppressant drugs may be recommended. The top priority in treating Kaposi sarcoma patients is strengthening the immune system. Additional treatments such as chemotherapy are not tolerated for long periods in people with existing immunity concerns.
- Local therapies. Some doctors may suggest topical treatments including injection of chemotherapy directly into lesions, cryosurgery, excisions, phototherapy or local radiation when there are only a few small lesions.
- Chemotherapy. Patients who do not see improvement in Kaposi sarcoma after addressing immune deficiencies may require chemotherapy as a follow-up treatment. Chemotherapy is usually administered intravenously, although some oral therapies are now being used.
- Immunotherapy. This type of treatment works by activating the immune system’s natural ability to fight cancer. Since it has already proven to be effective in treating many types of cancer, researchers are studying its application in Kaposi sarcoma treatment. Ask your doctor about clinical trials for immunotherapy and other emerging treatment approaches.
Surgery is not usually recommended because it is ineffective at curing the disease and lesions can recur.
What is the prognosis for Kaposi sarcoma?
Unlike early in the AIDS epidemic, Kaposi is very treatable. Very few people die from the disease because it usually responds to one treatment or another.
Data from the National Cancer Institute indicates that the five-year relative survival is about 72 percent. This means that five years after diagnosis, a person with Kaposi sarcoma is 72 percent as likely as the average person without Kaposi to still be living. With improvements in treatment, these numbers are likely to continue rising.
It’s also important to note that the cause of death for patients with Kaposi sarcoma is often something other than Kaposi sarcoma (e.g., HIV or AIDS-related diseases). And remember that survival rates are an average of a large group of people. Your own prognosis, which should be discussed with your doctor, depends on many factors, including your age, health and immune status as well as the extent of your disease.