Kaposi Sarcoma Definition

Kaposi’s Sarcoma – A CANCER that develops in the connective tissues that support the SKIN, with characteristic lesions on the skin and mucous membranes. There are several types of Kaposi’s sarcoma. The two that are most common in the United States are AIDS-related Kaposi’s sarcoma and transplant-related Kaposi’s sarcoma.

In 1994 researchers discovered that human herpesvirus 8 (HHV-8), sometimes called Kaposi’s sarcoma-associated herpesvirus (KSHV), causes Kaposi’s sarcoma. However, the path of transmission remains uncertain. Like other herpesvirus strains, HHV-8 can remain dormant in the body for years without manifesting symptoms. A healthy IMMUNE SYSTEM seems to hold HHV-8 in check, preventing it from causing disease. Prolonged compromise of immune function, through conditions such as HIV/AIDS or through IMMUNOSUPPRESSIVE THERAPY such as occurs following ORGAN TRANSPLANTATION, allows HHV-8 to replicate (reproduce itself by taking over healthy cells) and cause Kaposi’s sarcoma.

AIDS-related Kaposi’s sarcoma

Nearly all Kaposi’s sarcoma in the United States occurs in people, predominantly men, who have AIDS. Doctors consider the appearance of Kaposi’s sarcoma a defining sign that INFECTION with HIV (human immunodeficiency virus) has progressed to the disease state of AIDS. The activation of both HIV and HHV-8 may occur simultaneously, when both are present. Advances in treatment options for HIV/AIDS, notably highly active antiretroviral therapy (HAART), delay the progression of HIV to AIDS and consequently the appearance of Kaposi’s sarcoma. About 6 percent of men with HIV/AIDS who receive HAART develop Kaposi’s sarcoma, compared to 20 percent among those who do not.

Transplant-related Kaposi’s sarcoma

People who undergo organ transplantation typically receive immunosuppressive therapy, to prevent organ rejection, for the rest of their lives. The development of Kaposi’s sarcoma arises from the immunosuppression, not the organ transplantation. The American Cancer Society estimates that about 1 in 200 transplant recipients taking immunosuppressive therapy to prevent organ rejection develop Kaposi’s sarcoma. People who take longterm immunosuppressive therapy for other health conditions are also at risk for Kaposi’s sarcoma.

Symptoms of Kaposi’s Sarcoma and Diagnostic Path

The key symptom of Kaposi’s sarcoma is the presence of its characteristic lesions, which are nodular and raised, in people with long-term immunosuppression or who are HIV-positive. The lesions start as small, raised areas and are most common on the face, lower legs and feet, and genitals, though can develop anywhere on the body. They are usually darkly pigmented, often brownish red or purple, and sometimes itch. As they grow, the lesions may block the flow of blood or lymph, causing painful swelling. Lesions sometimes develop within the connective tissues of internal organs such as the LUNGS, where they can cause difficulty BREATHING, or the intestines, where they can cause GASTROINTESTINAL BLEEDING and ILEUS (intestinal obstruction).

The doctor can usually make a definitive diagnosis of Kaposi’s sarcoma on the basis of visible lesions and immune or HIV status, with biopsy of a representative lesion to confirm the diagnosis if necessary. A chest X-ray can determine the presence of lesions in the LUNGS. Other imaging studies such as COMPUTED TOMOGRAPHY (CT) SCAN and ENDOSCOPY can determine whether there are lesions elsewhere in the body, such as in the gastrointestinal tract, when symptoms suggest or the doctor suspects this is the case.

Kaposi’s Sarcoma Treatment Options and Outlook

Treatment depends to some extent on whether the Kaposi’s sarcoma is AIDS related or transplant related. In either form, methods to remove or reduce the lesions for improved comfort and appearance. Such methods may include

  • localized CHEMOTHERAPY (injecting a cytotoxic agent directly into the lesion)
  • external-beam RADIATION THERAPY that narrowly targets the lesion
  • the topical retinoid preparation alitretinoin (Panretin) applied to the lesion
  • surgery to reduce or excise (cut out) the lesion
  • liquid nitrogen or cryotherapy, which freezes the lesion

Systemic chemotherapy reduces lesions in recurrent, widespread, or systemic (involving internal organs as well as the skin) disease in AIDS-related Kaposi’s sarcoma, though it is not usually an option for transplant-related Kaposi’s sarcoma because the immune system cannot withstand the assault. Treatment for Kaposi’s sarcoma in people who have received organ transplants is often a delicate balance between suppressing enough immune function to stave off organ rejection and preserving enough immune response to fight INFECTION. Sometimes changing the immunosuppressive agent gives the immune system enough of a boost to fight the lesions, causing them to retreat or disappear.

Systemic Chemotherapy Agents to Treat Aidsrelated Kaposi’s Sarcoma
daunorubicin (DaunoXome)doxorubicin (Doxil)paclitaxel (Taxol)

For most cancers, doctors apply an algorithm of symptoms and progression that helps determine effective treatment options and prognosis (potential for improvement). Kaposi’s sarcoma occurs nearly always in circumstances of depressed or suppressed immune system function, skewing the conventional cancer-staging algorithms. The AIDS Clinical Trials Group (ACTG) system is the most commonly used staging algorithm for Kaposi’s sarcoma associated with AIDS or transplant-related immunosuppression. The ACTG system assesses three factors:

  • number of lesions
  • CD4 cell count, which represents immune system function
  • systemic conditions that indicate compromised immune function

Each factor receives a rating of zero (good) or one (poor), reflecting the likelihood for five-year survival, a standard prognosis marker for cancer. Kaposi’s sarcoma of the skin is seldom itself fatal, though the extent of its presence indicates the immune system cannot protect the body from infection. Kaposi’s sarcoma of internal organs can be fatal. This cancer is not curable in AIDS or active immunosuppressive therapy, so treatment aims to relieve symptoms.

Risk Factors and Preventive Measures

In the United States, HIV infection is the leading risk factor for Kaposi’s sarcoma. Methods to reduce exposure to HIV/AIDS also reduce the risk for Kaposi’s sarcoma. Most AIDS-related Kaposi’s sarcoma occurs in men who have sex with men, leading researchers to postulate that there is a route of sexual transmission for HHV-8. Safer sex practices are crucial.

As a result of the growing availability and acceptance of organ transplantation, the number of cases of Kaposi’s sarcoma among transplant recipients is steadily rising. The risk increases the longer the person receives immunosuppressive therapy. Newer immunosuppressive agents more selectively target the immune functions responsible for organ rejection, leaving other immune functions undisturbed.

See also CANCER TREATMENT OPTIONS AND DECISIONSHIV/AIDS PREVENTIONSEXUAL HEALTH; SEXUALLY TRANSMITTED DISEASE (STD) PREVENTION; SEXUALLY TRANSMITTED DISEASES (STDS); STAGING AND GRADING OF CANCER; VIRUS.

Kaposi’s sarcoma – cancer skin – treatment and symptoms
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