The effect of OPN expression on OS of 60 consecutive patients with normal cytogenetics treated with induction chemotherapy was examined in a multivariate Cox proportional hazards model that included age, WCC, and treatment center as potentially influential variables. After controlling for age and WCC, high OPN expression (high vs low) remained a significant predictive factor for OS (P = .01). Treatment center was not influential on prognosis after multivariate analysis (P = .9; data not shown), and there was no significant interaction between OPN and other prognostic variables at each treatment center. The assumptions for proportional hazards was not violated.