Staging is the process of using physical exams, imaging tests, and, in some cases, biopsy results to determine where and how much cancer is in the body. For many types of cancer, the stage is the most important factor in selecting treatment options and predicting a patient's outlook for recovery and survival. The results of the staging process are usually described in a standardized way, using a staging system.

There is no officially accepted system for staging all types of Kaposi sarcoma like there is for most other forms of cancer. But most doctors now use the AIDS Clinical Trials Group (ACTG) system.

Staging systems for most other types of cancer are based mostly on the size of the primary lesion (the first one to develop) and how far the cancer has spread from that lesion. But the outlook for patients with AIDS-related KS 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 of KS also considers factors such as how much the immune system is damaged and the presence of AIDS-related infections.

The AIDS Clinical Trial Group system

In 1988 a group of researchers known as the AIDS Clinical Trials Group (ACTG) proposed a staging classification system for AIDS-related Kaposi sarcoma. The ACTG system considers 3 factors:

• the extent of the tumor (abbreviated T)

• the status of the immune system (I), as measured by the number of certain cells (CD4 cells) present in the blood, and

• the extent of involvement within the body or systemic illness (S)

Under each of these major headings, there are 2 subgroups identified by either a zero (0, or good risk) or a 1 (poor risk). The following are the possible staging categories under this system:

T (tumor) status

T0 (good risk): Localized tumor

KS is only in the skin and/or the lymph nodes, 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) due to the tumor
• extensive oral KS: lesions that are nodular (raised) and/or lesions in areas of the mouth besides the palate
• Lesions of KS are in organs other than lymph nodes (such as the lungs, the intestine, the liver, etc.). Kaposi sarcoma in the lungs is a particularly bad sign.

I (immune system) status

I0 (good risk): CD4 cell count is 200 or more cells per cubic mm (the normal range is 600-1500 per cubic mm). More recent studies have used counts of either 150 or 100.

I1 (poor risk): CD4 cell count is lower than 200 cells per cubic mm. More recent studies have used counts of either 150 or 100.

S (systemic illness) status

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

No history of opportunistic infections or thrush (thrush is a fungal infection in the mouth, opportunistic infections are infections that rarely cause problems in healthy people, but more commonly affect people with suppressed immune systems).

None of the following B symptoms is present:

• unexplained fever
• night sweats
• more than 10% involuntary weight loss
• diarrhea persisting more than 2 weeks

And this is true:

• Karnofsky performance status 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
• performance status score under 70
• other HIV-related illness is present, such as neurological (nervous system) disease or lymphoma

Survival: Research has shown that people who are at good risk in any of these categories live longer than those who are not. As treatment of the HIV infection continues to improve, so does the outlook of KS. It takes time to see the effect of the most up to date treatment on survival rates, since they are based on patients first diagnosed years ago. The most recent data, from the National Cancer Institute's SEER program, shows an overall 5-year relative survival of about 60%. The cause of death for people with KS is not always the KS. Often, people with KS die from diseases related to HIV and AIDS, and not the KS itself.

When looking at patients staged by the ACTG staging system, those at good risk T and I factors combined, have a 5-year survival of 90%. For those at poor risk in these categories, the 5-year survival was around 50%. It dropped to 30% if the KS was in the lungs.

The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. Many of these patients live much longer than 5 years after diagnosis, and 5-year rates are used to produce a standard way of discussing prognosis. 5-year relative survival rates compare the observed survival with that expected for people without the cancer. This is a more accurate way to describe the outlook for patients with a particular type and stage of cancer. Of course, 5-year survival rates are based on patients diagnosed and initially treated more than 5 years ago. They may no longer be accurate. Improvements in treatment result in a more favorable outlook for recently diagnosed patients. With the introduction of newer treatment for AIDS, these rates are likely much better today.

Last Medical Review: 09/17/2009
Last Revised: 09/17/2009