Event-free survival (SE) of children with high-risk ALL who were PPR or PPR-only, treated in the AIEOP-ALL95 and AIEOP-ALL91 studies.

PPR-only is the subgroup of PPR patients who achieved CR and were negative for t(9;22) and t(4;11) translocations. By definition, this subgroup does not include resistant patients; thus, EFS resembles a disease-free survival type of analysis.