Treatment outcomes of adolescent acute lymphoblastic leukemia treated on Tokyo Children’s Cancer Study Group (TCCSG) clinical trials

Abstract

There is no standard treatment for adolescents aged 15 years or older with acute lymphoblastic leukemia (ALL), although this age group has been reported as having a poorer prognosis compared to younger patients. We retrospectively analyzed the outcomes of three consecutive Tokyo Children's Cancer Study Group ALL trials (1995-2006) of 373 patients aged 10 years or older, with particular focus on adolescents aged 15-18 years (older-adolescents n = 41), compared to those aged 10-14 years (younger-adolescents n = 332). The probability of event-free survival at 8 years was 67.5 ± 7.4 % for the older-adolescents and 66.5 ± 2.6 % for the younger-adolescents (p = 0.95). Overall survival was 70.7 ± 7.1 % for the older-adolescents and 74.3 ± 2.4 % for the younger-adolescents (p = 0.48). The differences between groups in relapse incidence, non-relapse mortality, and death rate during induction were not statistically significant, although the older-adolescents trended towards a higher frequency of having stem-cell transplantation during the first remission. In conclusion, our treatment strategy, which consists of intensive induction and block-type consolidation, provided improved outcomes for patients aged 15-18 years, comparable to those for patients aged 10-14 years.