Effect of time to complete remission on subsequent survival and disease- free survival time in AML, RAEB-t, and RAEB

The authors examined the relationship between the time required to enter complete remission (CR) after a first course of chemotherapy for newly diagnosed acute myeloid leukemia (AML), refractory anemia with excess blasts in transformation (RAEB-t), or refractory anemia with excess blasts (RAEB). They also examined subsequent survival time and disease-free survival time after accounting for cytogenetic status, age, and treatment. The data set consisted of 1101 patients with these diagnoses treated at the M.D. Anderson Cancer Center between 1980 and 1996 for whom outcomes were established after first-course therapy. Of the 1101 patients, 740 (67%) were in CR after this time; 508 of these 740 (69%) have died (80% had disease recurrence before death). The authors used the parametric model of Shen and Thall to estimate, in particular, T(c) (time to CR), T(C,D) (time from CR to death = residual survival after CR), and T(C,R) (residual disease-free survival [DFS] after CR) as functions of the covariates noted above and to estimate the dependence of T(C,D) and T(C,R) on T(C). There was a strong inverse association between T(C) and both T(C,D) and T(C,R) (P < .001 for both) that was independent of cytogenetic status, age, or treatment. The residual survival time of patients who required >50 days to enter CR was closer to the residual survival time of resistant patients than to that of patients known to be in CR within approximately 30 days of the start of treatment. Time to CR is an independent predictor of residual survival and disease-free survival in patients with newly diagnosed AML who achieve CR after 1 course of chemotherapy.