Stages of Kaposi Sarcoma

For most cancers, staging is a way of describing how widespread the cancer is. Staging is important for evaluating likely survival outcomes.

To evaluate the outlook for people with HIV/AIDS-related Kaposi sarcoma (KS), HIV related factors, such as measures of immune system functioning, are as important as how widely the cancer has spread. Most doctors use a staging pionered by the AIDS Clinical Trials Group as a system for characterizing HIV/AIDS-related KS.1,2 It includes three factors which are linked with survival. Factors associated with longer survival are labeled “good risk.” Factors associated with shorter survival are labeled “poor risk.”

AIDS clinical trials group staging system for HIV/AIDS-related KS2

  • T – Tumor: Tumor location, presence of swelling or ulceration
  • I – Immune system: How well the immune system is functioning, based primarily on CD4 t-cell count
  • S – Systemic illness: History or signs of opportunistic infections (OIs) and current ability to carry out daily activities

T Categories

The T categories are based on the extent and location of tumors.2 It also indicates whether tumors are causing symptoms such as swelling or ulceration.

The original study of this staging system showed that for the T categories, median survival was 27 months for good-risk patients. Median survival for the poor-risk patients was 15 months.3 In another study, the 3-year survival rate was 85% for good-risk and 69% for poor-risk patients.4

T Categories

Good Risk (0):

  • Tumors only found in the skin, lymph nodes, or roof of the mouth (palate), with only a small number of flat lesions found in the mouth

Poor Risk (1):

  • Tumors are causing swelling (fluid retention) or skin break down (sores or ulceration)
  • Many raised lesions found in the mouth
  • Lesions in the gastrointestinal (digestive) tract
  • Lesions on internal organs other than lymph nodes

I Categories

The I categories are based on how well the immune system is functioning.2 In a person with HIV infection, this is measured primarily by CD4 count. The CD4 count is the number of CD4 T-cells (T-lymphocytes) circulating in your blood stream per millimeter (mm) of blood tested.5 CD4 T-cells are immune cells (white blood cells) that protect your body from invaders and signal other cells of your immune system to take action against a pathogen. HIV destroys CD4 T-cells. Higher CD4 counts indicate that you are better able to fight infection.

The original study utilizing this grading system showed that for the I categories, median survival was 40 months for good-risk patients. Median survival for poor-risk patients was 13 months.3 In the second study, the 3-year survival rate was 83% for good-risk and 71% for poor-risk patients.4

N Categories

  • Good Risk (0): CD4 count ≥ 200 per mm3 of blood
  • Poor Risk (1): CD4 count <200 per mm3 of blood
  • Some recent studies use 150 or 100 per mm3 of blood as cut point

S Categories

The S categories are based on signs and symptoms of systemic (whole body) illness.2 Many viruses or bacteria are harmless to a person with a healthy immune system. But the same viruses or bacteria can make a person with a weak immune system seriously ill. The term for this is “opportunistic infection.” People with HIV are at risk of a number of opportunistic infections. Having an opportunistic infection like KS is linked to poorer outcome in people living with HIV.

The original study of this grading system showed that for the S categories, median survival was 22 months for good-risk patients. Median survival for the poor-risk patients was 16 months.3 The other study showed that the 3-year survival rate was 83% for good-risk and 63% for poor-risk patients.4

S Categories

Good Risk (0):

  • No history of opportunistic infections or thrush (oral candidiasis)
  • No “B” symptoms: unexplained fever, night sweats, >10% unplanned weight loss, diarrhea for more than 2 weeks
  • Karnofsky performance status ≥70: Able to care for yourself, even if you are unable to carry out daily activities or do active work.

Poor Risk (1):

  • History of opportunistic infections or thrush
  • “B” symptoms present
  • Karnofsky performance status <70

Putting it all together: assigning a stage

Once the cancer is characterized, the categories are combined to assign a stage.1 The I category has become less important since highly active antiretroviral therapy (HAART) has become available and widely used in the U.S. for people living with HIV. The I category is rarely used today to determine the KS risk group.1

Stages

Good Risk:

  • T0, S0
  • T1, S0
  • T0, S1

Poor Risk:

  • T1, S1
Written by: Sarah O'Brien | Last reviewed: May 2017.
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