KAPOSI'S SARCOMA
DEFINITION
Kaposi's sarcoma (KS; pronounced kuh-PO-seez sar-KO-muh) is a very rare form of cancer (see cancer entry). The word "sarcom" refers to any form of cancer that affects muscle, bone, liver, kidneys, lungs, spleen, bladder, and other organs and tissues. At one time, Kaposi's sarcoma was seen almost entirely in older men of Mediterranean or eastern European background. In the 1980s, however, it began to show up in young men with AIDS (see AIDS entry). Mild forms of the disease can be treated with topical (local) agents. More serious forms are treated with chemotherapy (treatment with drugs). KS is a major cause of death among people with AIDS.
DESCRIPTION
Scientists know of four forms of Kaposi's sarcoma. One form, called classical KS, affects older men of Mediterranean or eastern European background. The disease appears as pink, purple, or brown patches on the lower legs. These patches can be painful and ugly, but they are usually not life-threatening.
A second form of KS is called African endemic KS. It affects boys and men of any ethnic background. Its earliest symptoms are similar to those of classical KS. The cancer soon spreads, however, to tissues under the skin, the bones, and the lymph system. The disease is difficult to treat and often causes death within a few years of diagnosis.
Iatrogenic (pronounced eye-a-truh-JE-nik) KS is a third form of the disease. An iatrogenic disorder is one that develops because a patient is being treated for some other disease. Iatrogenic KS usually occurs in patients who have had a liver or kidney transplant. It is able to develop because these patients have taken drugs to suppress (restrain) their immune systems. Iatrogenic KS tends to disappear when these patients stop taking the drugs.
The fourth form of KS is AIDS-related KS. This form of KS appeared among gay men who developed AIDS in the 1980s. AIDS-related KS tumors first appear on the skin. But the disease may then spread to the head, neck, back, mouth, stomach and intestines, lymph nodes, and lungs. In its advanced stages, AIDS-related KS is very difficult to cure and can often cause death.
CAUSES
A variety of factors appear to lead to the development of KS:
- Genetic background. People with classic and African KS appear to possess an abnormal gene. Genes are chemical substances in the body that determine a person's physical and biological characteristics.
- Sex hormones. KS occurs far more often in men than in women. This suggests that sex hormones may have something to do with how the disease develops.
- Immune suppression. In many cases, the immune system may be strong enough to defend the body against KS. When the immune system is weakened, however, it loses that ability. People who are taking immunosuppressant drugs are, therefore, at risk for KS. So are people with AIDS, whose immune systems are often very badly damaged.
- Infectious agents that are sexually transmitted. Gay and bisexual men and intravenous drug users are all at high risk for AIDS. But gay and bisexual men are ten times more likely to develop KS than are intravenous drug users. That suggests that KS may be caused by some agent that is transmitted sexually. Further support for this idea comes from the fact that the rate of KS cases among gay and bisexual men has dropped dramatically as safer sex practices have become more widespread.
Kaposi's Sarcoma: Words to Know
- African endemic Kaposi's sarcoma:
- A form of KS that affects boys and men, has symptoms like those of classic KS, and can spread rapidly and cause death.
- AIDS-related Kaposi's sarcoma:
- A form of KS that occurs primarily in gay and bisexual men; it is much more dangerous than classic KS.
- Classic Kaposi's sarcoma:
- A form of KS that usually affects older men of Mediterranean or eastern European background.
- Iatrogenic Kaposi's sarcoma:
- A form of KS that develops in people who have had organ transplants and are taking immunosuppressant drugs.
Researchers have already found viruses they think may cause KS. One of the most likely candidates is called human herpes virus 8. This virus belongs to the same family that causes cold sores and shingles. The virus has been found in samples of KS taken from patients with the disease. Additional studies are still needed to confirm this theory.
SYMPTOMS
The symptoms of KS are quite visible and take the form of pink, purple, or brown patches that usually first appear on the lower legs.
DIAGNOSIS
KS can often be diagnosed simply by the appearance of the lesions (blotches) on a patient's skin. An unexplained cough or chest pain, or unexplained stomach or intestinal pain or bleeding, may suggest that the disease has spread to internal organs. A visual diagnosis of KS is usually confirmed with a biopsy. A biopsy is a process by which a small sample of tissue is taken from a patient. The sample is studied under a microscope to see what kinds of cells are present. KS cells have a very distinctive appearance that a scientist can recognize.
TREATMENT
There is no single best treatment for KS. The choice of treatment depends on the type of KS a patient has and how far it has spread. Doctors sometimes use a combination of treatments to obtain the best possible results. Some common treatments include:
Topical Therapy
Topical therapy is used when there are few lesions and the disease seems to be progressing slowly. In such a case, a doctor may freeze the lesions, which kills them. Radiation therapy can also be used on individual lesions. Radiation therapy involves the use of some form of radiation, such as X rays, to kill cancer cells.
Systemic Chemotherapy
In systemic chemotherapy, a patient is given drugs that enter his or her bloodstream and are carried throughout the body. The drugs can thus attack and kill cancer cells in all parts of the body. Doctors have found that a combination of cancer-killing drugs often works better than a single drug. Some commonly used drugs include vinblastine (pronounced vin-BLAS-teen), bleomycin (pronounced blee-uh-MYS-uhn), and doxorubicin (dok-suh-ROO-buh-suhn).
Antiviral Therapy
A number of drugs have been developed for the treatment of AIDS. Some of these drugs also appear to be effective against KS. Among the most promising of these drugs is a group of chemicals known as protease inhibitors. Some widely used antiviral drugs (drugs that kill viruses) have not, however, been effective in treating KS. These drugs include acyclovir (pronounced a-SI-klo-veer) and ganciclovir (pronounced gan-SI-klo-veer).
Other Treatments
A number of other treatments for KS are being studied. These include:
Alpha-interferon. Alpha-interferon is a chemical produced naturally in the body that fights infectious agents. It has been tested as a treatment for KS by injecting it directly into lesions.
- Retinoids. Retinoids are related to vitamin A. They have long been used to treat acne (see acne entry) and other skin diseases (see skin disorders entry). Some researchers believe that they also may be effective against KS lesions.
- Laser therapy. Laser therapy is similar to radiation therapy except that it uses laser light instead of X rays or other forms of radiation. Laser therapy has had limited success in destroying small lesions.
WHAT ARE INTERFERONS?
Infections are caused by bacteria, viruses, fungi, and other organisms. Doctors now have a number of tools to fight most of these disease-causing agents. For example, many bacterial infections can be cured by antibiotics. Viral infections, however, are a more difficult problem. Scientists have discovered relatively few drugs that will kill viruses. Some of the most promising of these drugs belong to a group known as the interferons.
Interferons were discovered in 1957 by the Scottish virologist Alick Isaacs and the Swiss virologist Jean Lindenmann. While studying influenza, Isaacs and Lindenmann made an unexpected discovery. Viruses in a cell had a way of preventing other viruses from entering the same cell. The viruses originally present in the cell produced a protein (chemical) that killed newly-arrived viruses. Isaacs and Lindenmann called the protein interferon because it "interfered" with the presence of other viruses.
At first, scientists thought that only one kind of interferon existed. But they have now discovered more than two dozen. Alpha-interferon is one type. It is being used to treat patients with Kaposi' sarcoma. Scientists are now investigating ways in which they will be able to make interferons work for them in fighting a number of diseases, including cancer.
Alternative Treatment
There is little evidence that any form of alternative treatment is effective against KS. Some practitioners recommend the use of herbal medicines and special diets.
PROGNOSIS
The prognosis for KS differs significantly for various forms of the disease. Patients with classic KS stand a good chance of complete recovery if they receive treatment soon enough. The prognosis for African endemic KS is not very good. The disease tends to spread rapidly and causes death within a relatively short period of time. Milder forms of AIDS-related KS can often be controlled. If the disease spreads to internal organs, however, prognosis is much less certain.
PREVENTION
There are no known methods for preventing classic and African endemic KS. AIDS-related KS can be prevented if those who are at risk for the disease (primarily gay and bisexual men) practice safer-sex methods. These methods prevent the spread of the infectious agent—whatever it is—from an infected to a noninfected person.
FOR MORE INFORMATION
Organizations
American Academy of Dermatology. 930 N. Meacham Road, PO Box 4014, Schaumburg, IL 60173. (847) 330-0230; (888) 462–3376. http://www.aad.org.
Gay Men's Health Crisis. 119 West 24th Street, New York, NY 10011. (212) 367-1000. http://www.gmhc.org.