EFS of children with CD2⁺CD19⁺ biphenotypic ALL. Percentages of 77 biphenotypic (long hatches), 1,631 BL (short hatches), and 347 TL (solid line) patients achieving EFS during 6 years of follow-up were calculated as described in Materials and Methods. The number of patients in each group remaining in follow-up at the indicated time points is shown in the inset. P values for comparisons of the biphenotypic group to the BL and TL groups are based on the pattern of outcome across the entire period of patient follow-up.