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Pathologic data correlated with relapse-free survival in primary GIST
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2010 Gastrointestinal Cancers Symposium
Mitotic rate along with tumor size and location correlated closely with recurrence-free survival in patients with primary gastrointestinal stromal tumor, and may serve as markers for selecting patients for adjuvant imatinib therapy, according to results of the phase-3 North American Intergroup trial ACOSOG Z9001 presented at the 2010 Gastrointestinal Cancers Symposium.
Researchers randomly assigned 713 patients who underwent complete gross resection of a primary GIST measuring at least 3 cm and expressing KIT to 400 mg daily imatinib or placebo. Patients underwent serial cross-sectional imaging. Mitotic rate, size of tumor and location of tumor were available for 620 patients.
Mitotic rate was five or greater in 37% of patients. Tumor size was smaller than 5 cm in 41% of patients, between 5 cm and 10 cm in 34% of patients, and larger than 10 cm in 25% of patients. Tumors were located in the stomach (62%), small bowel (31%), rectum (1%), or other (6%).
At two-years, recurrence-free survival was 91% in patients assigned imatinib vs. 74% in patients assigned placebo.
Multivariate analysis showed that high mitotic rate (HR=11.3; P<.0001), tumor size (HR=2.0; P<.0001) and tumor in the small bowel (HR=1.7; P=.02) were predictive of recurrence-free survival, according to Martin E. Blackstein, MD, PhD, associate professor of medicine with the University of Toronto, who presented the results.
“The mitotic index, as well as size and location in the GI tract in the trial are excellent predictors of relapse-free survival,” Blackstein said. – by Jason Harris
For more information:
- Blackstein ME. #6.Presented at: the 2010 Gastrointestinal Cancers Symposium; Jan 22-24; Orlando, Fla.
