Kaposi sarcoma is a disease in which cancer cells are found in the skin or mucous membranes that line the gastrointestinal (GI) tract, from mouth to anus, including the stomach and intestines.
These tumors appear as purple patches or nodules on the skin and/or mucous membranes and can spread to lymph nodes and lungs. Kaposi sarcoma is more common in men and in patients with suppressed immune systems.
What causes Kaposi sarcoma?
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.
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