Kaposi Sarcoma Stages

After someone is diagnosed with Kaposi sarcoma, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes the extent of the cancer in the body. It helps determine how serious the cancer is and how best to treat it. The stage is one of the most important factors in deciding how to treat the cancer and determining how successful treatment might be.

How is the stage determined?

The results of the staging process are usually described in a standard way, using a staging system. Staging systems for most other types of cancer are based on the size of the primary tumor (the first one to develop) and how far the cancer has spread from there. But for people with AIDS-related Kaposi sarcoma (KS), the most common type in the United States, the outlook is influenced at least as much by the presence of other AIDS-related problems as it is by the spread of KS. For this reason, staging KS also considers factors such as how much the immune system is damaged and the presence of AIDS-related infections.

There is no officially accepted system for staging KS like there is for most other forms of cancer. But for AIDS-related KS, most doctors use the AIDS Clinical Trials Group system.

The AIDS Clinical Trial Group system

The AIDS Clinical Trials Group (ACTG) system for AIDS-related KS considers 3 factors:

• The extent of the tumor (T)
• The status of the immune system (I), as measured by the number of CD4 cells (a specific type of immune cell) in the blood
• The extent of systemic illness (S) within the body (how sick is the person from the cancer or the HIV)

Under each major heading, there are 2 subgroups: either a 0 (good risk) or a 1 (poor risk). The following are the possible staging groups under this system:

T (tumor) status

T0 (good risk): Localized tumor

KS is only in the skin and/or the lymph nodes (bean-sized collections of immune cells throughout the body), and/or there is only a small amount of disease on the palate (roof of the mouth). The KS lesions in the mouth are flat rather than raised.

T1 (poor risk): The KS lesions are widespread. One or more of the following is present:

• Edema (swelling) or ulceration (breaks in the skin) due to the tumor
• Extensive oral KS: lesions that are nodular (raised) and/or lesions in areas of the mouth besides the palate (roof of the mouth)
• Lesions of KS are in organs other than lymph nodes (such as the lungs, the intestine, the liver, etc.). Kaposi sarcoma in the lungs can sometimes mean a worse prognosis (outcome).

I (immune system) status

The immune status is assessed using a blood test known as the CD4 count, which measures the number of white blood cells called helper T cells.

I0 (good risk): CD4 cell count is 150 or more cells per cubic millimeter (mm³).

I1 (poor risk): CD4 cell count is lower than 150 cells per mm³.

S (systemic illness) status

S0 (good risk): No systemic illness present; all of the following are true:

• No history of opportunistic infections (infections that rarely cause problems in healthy people but affect people with suppressed immune systems) or thrush (a fungal infection in the mouth).
• No B symptoms lasting more than 2 weeks. B symptoms include:Unexplained fever; night sweats (severe enough to soak the bed clothes); weight loss of more than 10% without dieting
• Karnofsky performance status (KPS) score of 70 or higher. This means you are up and about most of the time and able to take care of yourself.

S1 (poor risk): Systemic illness present; one or more of the following is true:

• History of opportunistic infections or thrush
• One or more B symptoms is present
• KPS score is under 70
• Other HIV-related illness is present, such as neurological (nervous system) disease or lymphoma

Overall risk group

Once these features have been evaluated, patients are assigned an overall risk group (either good risk or poor risk). In fact, since highly active antiretroviral therapy (HAART) became available to treat HIV, the immune status (I) has become less important and is often not counted in determining the risk group:

• Good risk: T0 S0, T1 S0, or T0 S1
• Poor risk: T1 S1