Where should adolescents with ALL be treated?

Currently, 50% of adolescents with ALL are treated by adult teams and 50% by paediatric teams (following either adult or paediatric protocols). The aim of this paper is to review the results obtained with first-line chemotherapy and with haematopoietic SCT (HSCT) in adolescents with ALL. Disease biology and host factors are responsible for the differences observed between adolescents and other age categories. The outcome of adolescents with ALL after first-line chemotherapy is poorer as compared with children, although better as compared with adults. Recent studies have shown that adolescents who were enrolled in paediatric trials achieved better results than those who were enrolled in adult trials. This is most likely because of several differences, including protocol design, dose intensity and use of HSCTs, as well as better compliance to treatment and better supportive care. Disparities in the attitude towards treatment between paediatric and adult wards might also contribute to the better outcome that is observed in paediatric institutions. Indications for HSCT in children with ALL are well defined by international protocols. Only very high-risk paediatric patients are eligible for HSCT in CR1, whereas in adult trials, allogeneic or autologous HSCT are frequently offered, even to standard-risk patients in CR1. The outcome of adolescents given HSCT is poorer than in children, though better than in adults. Improving both psychosocial support during therapy and physical exercise habits represent further challenges for teams involved in the treatment of adolescents. Cooperation between paediatric and adult haematologists would surely improve the ability to recruit as many patients as possible and would promote progress in the research on adolescents. In conclusion, redefining age limits according to risk-based strategies, as well as encouraging multi-centre cooperation, should be taken into consideration to improve the outcome of this age category. Adolescents should be referred to research treatment teams that have experience in the management of paediatric ALL and they should be enrolled in international cooperative studies.