Kaposi's Sarcoma

Definition

Kaposi's sarcoma is a form of skin cancer that can involve internal organs. It most often is found in patients with acquired immunodeficiency syndrome (AIDS ), and can be fatal.

Description

Kaposi's sarcoma (KS) was once a very rare form of cancer, primarily affecting elderly men of Mediterranean and eastern European background, until the 1980s, when it began to appear among AIDS patients. It manifests in four distinct forms. The first form, called classic KS, was described by the Austrian dermatologist Moricz Kaposi more than a century ago. Classic KS usually affects older men of Mediterranean or eastern European backgrounds by producing tumors on the lower legs. Though at times painful and disfiguring, they generally are not life-threatening. The second form of the disease, African endemic KS, primarily affects boys and men. It can appear as classic KS, or in a more deadly form that quickly spreads to tissues below the skin, the bones and lymph system, leading to death within a few years of diagnosis. Another form of KS, iatrogenic KS, is observed in kidney and liver transplant patients who take immunosuppressive drugs to prevent rejection of their organ transplant. Iatrogenic KS usually reverses after the immunosuppressive drug is stopped. The fourth form of KS, AIDS-related KS, emerged as one of the first illnesses observed among those with AIDS. Unlike classic KS, AIDS-related KS tumors generally appear on the upper body, including the head, neck, and back. The tumors also can appear on the soft palate and gum areas of the mouth. In more advanced cases, they can be found in the stomach and intestines, the lymph nodes, and the lungs.

Incidence of Kaposi's sarcoma has been reported as high as 20% in homosexual men who have HIV, 3% in heterosexual intravenous drug users, 3% in women and children, 3% in transfusion recipients, and 1% in hemophiliacs. Once regarded as only a defining illness for AIDS, KS has proven to be a progressive, fatal disease on its own, especially when the disease becomes systemic. Yet involvement throughout the body is not the only factor in patient mortality. Research in 2000 found that patients with KS in oral mucosa had a higher risk of death than those with KS appearing only on the skin.

Causes and symptoms

A variety of factors appear to contribute to the development of KS. One of the first avenues offered as causal agents was genetic predisposition. People with classic KS, and those who develop the tumors after transplantation, are more likely than others to possess a genetically determined immune factor called HLA-DR. Cases of KS that run in families, however, are rare.

The fact that the disease is more likely to afflict men than women suggests sex hormones, such as testosterone in men, may stimulate the growth of KS tumors, and that estrogen in women may retard their growth.

Immune suppression was the next likely cause since liver, kidney, and bone marrow patients who take immunosuppressive drugs to prevent transplant rejection frequently develop KS lesions. Similarly, KS has been observed in patients receiving systemic treatment with high-dose corticosteroids, which also suppresses the immune system. Immune suppression is the hallmark of AIDS.

The current theory is the discovery of an infectious agent. A number of viruses have been proposed as possible causes, including cytomegalovirus and human papilloma virus, fragments of which have been found in KS tumor specimens. A more likely candidate, however, is a new herpes virus that has been called human herpes virus 8 (HHV-8) or KS-associated herpes virus (KSHV). Since fragments of the virus were first disclosed in KS samples in 1994, they have since been found in KS samples taken from patients with classic KS, African endemic KS, and KS in transplant patients. Fragments of HHV-8, however, also have been found in patients who have other skin diseases but who do not have KS.

Studies in 2000 showed that HHV-8 was indeed the culprit behind KS. Nevertheless, it does not work alone. In combination with a patient's altered response to cytokines (regulatory proteins produced by the immune system) and the HIV-1 transactivating protein Tat which promotes the growth of endothelial cells, HHV-8 can then encode interleukin 6 viral proteins. These specific cytokines stimulate cell growth in the skin, becoming KS.

HHV-8 destroys the immune system further by directing a cell to remove the major histocompatibility complex (MHC-1) proteins that protect it from invasion. These proteins then are transferred to the interior of the cell and are destroyed. This leaves the cell unguarded and vulnerable to invaders which normally would be targeted for attack by the immune system.

Research in early 2001 showed that transmission of HHV-8 virus can be more casual than once was thought, giving rise to incidence among women and children. Women who are intravenous drug users and who also have had a sexually transmitted disease have been found to harbor HHV-8. This evidence shows that women can contract HHV-8 through blood. In addition, researchers in 2000 found that HHV-8 could be transmitted orally though kissing. This study found more HHV-8 virus in oral samples than in genital secretions. In fact, HHV-8 was difficult to find in genital samples. This may indicate why children and women who were not intravenous drug users have had KS.

MORIZ KAPOSI, (1837–1902)

Moriz Kohn Kaposi was born in 1837 to very poor Hungarian parents. He studied dermatology under Ferdinand von Hebra at the University of Vienna, earning his medical degree in 1861. Kaposi took a position in Hebra's clinic and ultimately became a lecturer where he was responsible for educating numerous dermatologists. Kaposi and Hebra coauthored The Handbook of Diseases of the Skin which had great success. Kaposi married Hebra's daughter and the couple had one son, Hermann (1872). When Hebra died, Kaposi filled the vacant spot as director of the skin clinic and as Vienna's most renowned dermatologist.

Between 1872 and 1887, Kaposi discovered nine skin diseases that had not been previously documented. His discovery of a malignant disease that strikes the lymph nodes and skin (Kaposi's sarcoma 1872) has been documented as the most noteworthy. This disease was seen relatively rarely in the United States until the 1980s when it was tied to AIDS. This sarcoma has been the most common tumor found in AIDS patients. In 1872, Kaposi also studied cases of lupus erythematosus, which had no previous documentation. Kaposi was a prolific writer who published Pathology and Treatment of Diseases of the Skin in addition to numerous other publications, which he completed individually and with other authors. Kaposi died in 1902.

Kaposi's sarcoma produces pink, purple, or brown tumors on the skin, mucous membranes, or internal organs.

Diagnosis

Many physicians will diagnose KS based on the appearance of the skin tumors and the patient's medical history. Unexplained cough or chest pain, as well as unexplained stomach or intestinal pain or bleeding, could suggest that the disease has moved beyond the skin. The most certain diagnosis can be achieved by taking a biopsy sample of a suspected KS lesion and examining it under high-power magnification. For suspected involvement of internal organs, physicians will use a bronchoscope to examine the lungs or an endoscope to view the stomach and intestinal tract.

Treatment

Treatment goals for KS are simple: to reduce the severity of symptoms, shrink tumors, and prevent disease progression. Unfortunately, there is no single best treatment plan that can achieve all of these goals. Treatments range from topical agents for mild disease with few tumors to more aggressive systemic chemotherapy for more serious KS that has spread to large areas of skin or the internal organs. Physicians will frequently combine topical, radiation, and various systemic chemotherapy drugs, depending on the sites of the body affected, the speed at which it is progressing, and the patient's overall health, among other considerations.

Local therapy

When the number of KS tumors is small and the disease appears to be progressing slowly, physicians have had great success with the application, by the patient, of a topical gel containing alitretinoin. This product is a naturally occurring retinoid (a derivative of vitamin A) that can inhibit cell growth and activate apoptosis (cell death). Patients tolerate the product well with only mild to moderate skin irritation at the site of application in some individuals. Duration of treatment is long term, with the patient seeing results after four to eight weeks of therapy. Treatment slows the progress of the disease and reduces the size of the lesions.

Other local treatments include cryotherapy (using a liquid nitrogen spray or probe to freeze the tumor), injections of vinblastine (a drug also used for systemic chemotherapy) directly into the tumor, laser therapy, or radiation therapy targeted at the tumor sites. These methods have some success, but they also have unpleasant side effects. Vinblastine injections are about 70% effective, but they do not resolve the lesions completely.

Systemic chemotherapy

With widespread KS lesions over the body surface, or evidence of spread to other parts of the body, physicians will consider systemic chemotherapy drugs. A new class of chemotherapy drugs, called liposomal anthracyclines, appears to produce good results with fewer toxic side effects than do more conventional chemotherapy drugs. Two of these drugs, liposomal doxorubicin (Doxil) and liposomal daunorubicin (DaunoXone) have become the treatment of choice. These drugs last longer in the human body, demonstrate higher concentrations of the drug in tumors, and have fewer toxic side effects.

Paclitaxel (Taxol) is the newest drug in the KS arsenal. It has a 75% effective rate and is very effective in patients who are resistant to anthracycline drugs. The 3-hour infusion time and the incidence of bone marrow suppression, hair loss, and joint and muscle pain make it less attractive to patients.

Antiretroviral therapy

Evidence suggests that for some individuals, the class of AIDS drugs called protease inhibitors, in combination with other anti-HIV drugs, can reduce the levels of detectable HIV in the blood to nearly zero, and in some patients stabilize or reverse KS tumors. A study late in 2003 showed that highly active antiretroviral therapy (HAART) containing a protease inhibitor helped block KS tumor growth, invasion and distant spread. HAART is a treatment used to treat HIV patients. Since the discovery of HHV-8, interest in an antiviral approach to KS has increased. There is no evidence, however, that two antiviral drugs commonly prescribed for herpes, acyclovir and ganciclovir, have any effect on the disease. One study of 20,000 patients with HIV and AIDS found that those who took foscarnet, another antretroiviral medication that works in a different way than acyclovir and ganciclovir, were less likely to develop KS tumors.

Another treatment source is interferon-alpha, which is made by the body and has powerful effects on the immune system. Investigators have tried injecting it directly into lesions, and also in combination with other anti-HIV drugs such as zidovudine, with some success. It has been used with patients who have KS limited only to the skin and who have little immunosuppression. Interferon-alpha has had poor tumor response and significant toxic effects in patients, especially those with seriously-depressed immune systems.

Still other avenues of therapy being researched are sex hormones, thalidomide, SU5516 (an endothelial growth factor inhibitor), and angiogenesis inhibitors, which prevent the growth of blood vessels within a cell that supplies oxygen and nutrients. There also is some research involving the oral administration of alitretinoin.

Alternative treatment

The Bastyr University AIDS Research Study has been investigating and collecting data on treatment for KS and other opportunistic conditions that are AIDS-related. Among the treatments under investigation are nutritional and herbal therapies (both internal and external). Bastyr University is located in Seattle, Washington.

Prognosis

The prognosis for patients with classic KS is good. Tumors can frequently be controlled and patients frequently die of other causes before any serious spread. African endemic KS can progress rapidly and lead to premature death, despite treatment. In AIDS-related KS, milder cases can frequently be controlled; the prognosis for more advanced and rapidly progressing cases is less certain and dependent on the patient's overall medical condition. There are indications that KS can be stabilized or reversed in patients whose level of HIV in the blood is reduced to undetectable levels via combined antiretroviral therapy.

KEY TERMS

African endemic Kaposi's sarcoma— Affects men and boys; can appear like classic KS or in a more lethal form.

AIDS-related Kaposi's sarcoma— Emerged as one of the first illnesses associated with AIDS patients. These tumors usually appear on the upper body, the soft palate and gum areas, and, as the disease advances, in the lymph nodes, stomach, intestines, and lungs.

Apoptosis— Cell death.

Classic Kaposi's sarcoma— Usually affects older men of Mediterranean or eastern European backgrounds, and produces tumors on the lower legs.

Cytokines— Regulatory proteins that are produced by the immune system.

Human herpesvirus 8— Also called Kaposi's sarcoma-associated herpesvirus (KSHV). Thought to be a viral cause for KS.

Iatrogenic Kaposi's sarcoma— Develops in transplant patients who take immunosuppressive drugs to prevent rejection of their organ transplant.

MCH-1— Major histocompatibility complex proteins that protect cells from invasion.

Prevention

Safer sex practices may help to prevent AIDS-related KS by decreasing the risk of transmission of HHV-8 through sexual means. However, the addition of avoidance of deep kissing to those precautions may be necessary. Intravenous drug users should still be urged not to share needles. Treatment with antiretrovirals may help to preserve the function of the immune system in HIV patients and delay the appearance and progression of KS lesions. In fact, since the introduction of HAART in those infected with HIV, KS has decreased substantially. However, it still remains the most common cancer among those infected with HIV.

Large clinical trials underway in 2003 were showing some promise for preventing infection with HHV-8 through prophylaxis (preventive medication) with antiherpes drugs.

Resources

PERIODICALS

"Alitretinoin Gel Effective for Treating Lesions." AIDS Weekly February 12, 2001.

Cannon, Michael J., A. Scott Laney, and Philip E. Pellett. "Human Herpesvirus 8: Current Issues." Clinical Infectious Diseases July 1, 2003: 82-86.

Dezube, Bruce J. "AIDS-Related Kaposi Sarcoma." Archives of Dermatology 136, no. 2 (December 2000): 1554.

Henderson, Charles W. "Kissing May Spread Cause of Kaposi's Sarcoma." Cancer Weekly November 21, 2000: NA.

Mann, Arnold. "Kaposi's Lesions Benefit from Long-Term Alitretinoin Gel Use." Family Practice News 30, no. 19 (October 1, 2000): 12.

"Protease Inhibitors Used for Treating HIV also Block Kaposi Sarcoma." Cancer Weekly 30, no. 19 (November 4, 2003): 125.

Rohrmus, Bettina, Eva M. Thoma-Greber, Hohannes R. Bogner, and Martin Rocken. "Outlook in Oral and Cutaneous Kaposi's Sarcoma." The Lancet 356, no. 9248 (December 23, 2000): 2160.

Kaposi's sarcoma

Definition

Kaposi's sarcoma (KS), also called multiple idiopathic hemorrhagic sarcoma, is a neoplastic disease associated especially with AIDS , usually affecting the skin and mucous membranes.

Description

Causes & symptoms

Kaposi's sarcoma (KS) is caused by herpesvirus 8. Malignant cells are found in the tissues under the skin or mucous membranes that line the mouth, nose, and anus. KS causes red or purple patches on the skin and/or mucous membranes and spread to other organs, such as the lungs, liver, or intestinal tract. KS is seen in three forms:

• indolent
• lymphadenopathic
• AIDS-related

The primary distinction between the three forms of KS is the rate of growth and the location of the lesions. In the past, the indolent form of Kaposi's sarcoma was the most common, and was most often seen in men over the age of 60 years of Jewish or Italian ancestry; in African men; and in patients who had organ transplants or had their immune systems impaired for other reasons. KS was frequently left untreated. Because of its slow growth, the cancer was not a threat to the patient. Since the 1980s, a far higher percentage of cases with rapid growth have been observed, usually accompanied by AIDS (HIV disease).

The aggressive form of KS is seen in about one-third of patients with AIDS, and has become endemic in equatorial African. In African nations, aggressive KS is seen most often among young men and children.

Lymphadenophic KS affects the lymph nodes as well as the skin structures.

Diagnosis

KS is traditionally diagnosed based on the red or purple patches on the skin or mucous membranes. A biopsy is usually performed in order to verify the diagnosis. Since other cancers may have a similar appearance to KS, it is often useful to test for the presence of human herpesvirus 8 in order to confirm the diagnosis.

Treatment

In indolent KS, localized treatment is often adequate. Superficial lesions may be removed surgically. Alternatives are radiation therapy, electrical curettage, in which the lesion is burned with an electrical current, or cryotherapy, in which a source of extreme cold, such as liquid nitrogen, is applied to the cancer in order to kill the cells.

Among patients who develop KS after an organ transplant, reduction in the dose of drugs used to control the immune response may be enough to control or eliminate the cancer, although this treatment increases the risk of transplant rejection. One report from the University of Barcelona in Spain states that a change of medication may resolve the problem of KS after transplantation.

In KS associated with AIDS, systemic chemotherapy is usually required.

The Gay Men's Health Crisis (GMHC) has reviewed a number of alternative therapies which have been tried in KS, but none have shown consistently favorable results. Among the treatments mentioned were shark cartilage, herbal and purifying massage therapies to enhance immune function, and transcendental meditation . Homeopathy has been tried, but here too the results have not been reliable.

Allopathic treatment

There are no current best-practice treatments for KS. For rapidly growing KS, a standard treatment is systemic chemotherapy with a combination of adriamycin, bleomycin, and vincristine (ABV); however, several studies have reported that single-agent treatments may be as effective as combinations. Single-agent treatments that have shown evidence of effectiveness are a liposomal form of adriamycin used alone; methotrexate, and trimetrexate. Interferon-alpha has also been reported to be effective in AIDS-related KS.

Expected results

The expected results depend primarily on the underlying condition of the patient. Those patients who have classic slow-growing KS may live many years, even in the absence of treatment. For patients with AIDS, a proposed staging system has divided patients into low- and high-risk groups, depending both on the extent of the sarcoma and their underlying immune function. Patients with well-functioning immune systems, no AIDS associated opportunistic infections , and KS confined to the skin have an estimated survival of about three years. Those with impaired immune systems, other infections, and more widespread KS have an estimated survival of about one year. Overall length of survival will depend on the patient's response to treatment.

Prevention

The United States Public Health Service (USPHS) guidelines for prevention of KS call for prophylactic administration of drugs that are effective against human herpesvirus-8. The primary drugs for this purpose are foscarnet and ganciclovir. In each case, the dose must be adjusted based on the patient's condition. While the USPHS recognizes that KS may affect children as well as adults, no formal recommendations for prevention have been published.

Resources

BOOKS

Abeloff M. D., J. O. Armitage, A. S. Lichter, and J. E. Nieder-huber, editors. Clinical Oncology, 2nd edition. New York: Churchill Livingston, 2000.

PERIODICALS

Campistol, J. M., A. Gutierrez-Dalmau, and J. V. Torregrosa. "Conversion to sirolimus: a successful treatment for post-transplantation Kaposi's sarcoma." Transplantation (March 2004): 760–2.

Chao, S. C., J. Y. Lee, and C. J. Tsao. "Treatment of classical type Kaposi's sarcoma with paclitaxel." Anticancer Res (January-February 2001): 571–3.

Cheuk, W., K. O. Wong, C. S. Wong, J. E. Dinkel, D. Ben-Dor, and J. K. Chan. "Immunostaining for human herpesvirus 8 latent nuclear antigen-1 helps distinguish Kaposi sarcoma from its mimickers." Am J Clin Pathol (March 2004): 335–42.

"DaunoXome offers KS treatment alternative." Aids Alert (June 1996): 67–8.

OTHER

"Prevention of disease recurrence." 1999 USPHS/IDSA guidelines for the prevention of opportunistic infections in persons infected with HIV: Part III. United States Public Health Service/Infectious Diseases Society of America, 1999.

"Prevention of the first episode of disease." 1999 USPHS/IDSA Guidelines for the Prevention of Opportunistic Infections in Persons Infected with HIV: Part II. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention. U.S. Public Health Service/Infectious Diseases Society of America, 1999.

Samuel Uretsky, Pharm.D.

Kaposi's sarcoma , a usually fatal cancer that was considered rare until its appearance in AIDS patients. First described by an Austro-Hungarian physician, Moritz Kaposi, in 1872, it appears in three forms and is characterized by vascular skin tumors. Kaposi's sarcoma is endemic in Africa, where it is more aggressive, seen in children and young men, and accounts for 10% of malignancies in Congo (Kinshasa) and Uganda. A mild form of the disease is sometimes seen in elderly men of Mediterranean origin. The development of AIDS-related Kaposi's sarcoma has been linked to a virus of the herpes group. In the early 1980s it was seen in nearly 50% of AIDS patients, but the proportion has decreased since that time. In AIDS, Kaposi's presents as barely raised pink or red papules or plaques that become widely disseminated on the skin and in the gastrointestinal and respiratory tracts, where they may cause extensive bleeding. Treatment includes chemotherapy or surgical excision, cryosurgury (destruction by freezing), or electrodessication (destruction by heat). Local radiation therapy can also be effective. AIDS patients are treated with Vinblastine, an active, but weak, agent, which further lowers immunity.

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.

Kaposi's sarcoma (kap-oh-siz) n. a malignant tumour arising from blood vessels in the skin and appearing as purple to dark brown plaques or nodules. It is common in Africa but rare in the Western world, except in patients with AIDS. The tumour evolves slowly; radiotherapy is the treatment of choice for localized lesions and chemotherapy may be of value in metastatic disease. See AIDS. [ M. Kaposi (1837–1902), Austrian dermatologist]