Probability of second leukemia recurrence. A indicates chemotherapy recipients after an early first relapse; B, transplant recipients with TBI regimens after an early first relapse; C, transplant recipients with non-TBI regimens after an early first relapse; D, chemotherapy recipients after late first relapse; E, transplant recipients with TBI regimens after late first relapse; and F, transplant recipients with non-TBI regimens after late first relapse.