Nilsson et al developed a risk score for evaluating patients with a gastrointestinal stromal tumor (GIST). This can be helpful in identifying more aggressive tumors that may benefit from more aggressive management. The authors are from the University of Goteborg in Sweden.
NOTE: The patients all were managed prior to the availability of preimatinib mesylate (Glivec) that targets the KIT tyrosine kinase receptor. The risk score can help identify patients who may benefit from Glivec therapy.
Parameters:
(1) diameter of the tumor in cm
(2) maximum proliferative Ki-67 index
The maximum proliferative Ki-67 index involved:
(1) Stain a section of the tumor for Ki-67.
(2) Identify an area with the most intense nuclear staining ("hot spot").
(3) Count the percentage of positive cells in a single high powered microscopic field (with area of 0.16 square mm)
GIST risk score =
= (diameter of the tumor in cm) + (percent of cells staining with Ki-67 as a whole number)
Interpretation:
• minimum risk score: around 1
• maximum risk score: > 110
• For each percentage increase in maximum Ki-67 staining the risk of dying increased 5% (Figure 2, page 825).
• For each 1 cm increase n tumor size the risk of dying increased 5% (Figure 3, page 825).
• A score <= 7 was considered low risk for disease progression and tumor-related death.
• A score > 7 was considered high risk for disease progression and tumor-related death.
|
Risk Group
|
Percent with Tumor Related Death
|
Median Overall Survival
|
|
low risk
|
< 1%
|
14.3 years
|
|
high risk
|
47%
|
6.0 years
|
after Table 3, page 827
