Staging and Understanding Your Risk Score

Staging is the process doctors use to describe the extent of a cancer and how much it has spread. For Kaposi sarcoma (KS), the most widely used framework is the ACTG TIS system, developed by the AIDS Clinical Trials Group ^[1]. While originally designed for HIV-associated KS, it provides a vital map for understanding how the disease is behaving in your body.

The TIS Framework: Breaking Down the Scores

The system evaluates three specific areas: Tumor, Immune system, and Systemic illness. For each category, you are assigned a score of 0 (Good Risk) or 1 (Poor Risk) ^[1][1].

T: Tumor Extent

This measures where the KS is and how it is affecting your physical structure.

• T0 (Good Risk): The KS is limited to the skin or lymph nodes. If there are spots in the mouth, they are only on the roof (palate). There is no significant swelling or open sores ^[1][2].
• T1 (Poor Risk): This indicates more advanced disease. It includes:
  • Edema: Significant swelling caused by the tumor blocking lymph fluid ^[2].
  • Ulceration: Lesions that have broken open or become sores ^[1].
  • Extensive Oral KS: Lesions appearing on the tongue, gums, or throat ^[3].
  • Visceral Involvement: KS found in internal organs like the lungs or digestive tract ^[4][5].

I: Immune Status

This looks at the health of your immune system, specifically your CD4 count (a type of white blood cell).

• I0 (Good Risk): A CD4 count of 200 cells/mm³ or higher ^[1].
• I1 (Poor Risk): A CD4 count below 200 cells/mm³ ^[1].
• Note: In the era of highly effective modern HIV medications, the “I” score has become much less important in predicting survival than it used to be. Many people with low counts recover rapidly once starting treatment ^[1][6].

S: Systemic Illness

This assesses your overall health and whether you have symptoms that affect your whole body.

• S0 (Good Risk): You feel generally well, have no “B symptoms” (which are unexplained fevers, drenching night sweats, or losing more than 10% of your body weight without trying), and have not had other major opportunistic infections ^[1][7].
• S1 (Poor Risk): You have “B symptoms,” a history of other serious infections, or a “poor performance status,” meaning you are often too weak to perform typical daily activities, need significant assistance, or are bedridden ^[1][7].

Risk Stratification: What the Scores Predict

Doctors use these scores to predict how the disease might progress and to tailor the intensity of your treatment.

• Short-term Outcomes (0–4 months): The S (Systemic) score is the strongest predictor of health in the months immediately following diagnosis. An S1 score often signals a need for more urgent, supportive care to stabilize your overall health ^[1].
• Long-term Outcomes (4–24 months): The T (Tumor) score is the most accurate predictor of long-term survival. Patients with T1 disease generally require more intensive systemic treatments, such as chemotherapy, to manage the higher tumor burden ^[1][8].

Limitations for Other KS Subtypes

The ACTG TIS system was built specifically for HIV-associated KS. If you have Classic, Endemic, or Iatrogenic KS, your staging might look different ^[9].

• Classic KS: Staging is often simpler, focusing only on whether the disease is localized to the skin or has spread to internal organs ^[9].
• Iatrogenic KS: The most important “stage” factor is often the type and amount of immunosuppressive medication you are taking, rather than your CD4 count ^[10][11].
• Endemic KS: In children, staging focuses heavily on lymph node involvement, which is more common in this subtype ^[4].