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Derivation of the study cohort. aThe number of blood samples analyzed was based on a priori power calculations estimating that a sample of approximately 1000 patients would provide a power of 0.96 for testing the null hypothesis of independence of 2-year overall survival over quintiles of insulin-like growth factor-1 at a statistical significance level of .05. CALGB = Cancer and Leukemia Group B, now Alliance for Clinical Trials in Oncology.
