Clinical characteristics, biologic features and outcome for young adult patients with acute lymphoblastic leukaemia.

Young adult patients with acute lymphoblastic leukaemia (ALL) represent a unique epidemiologic subgroup in that therapy may be provided by either adult or paediatric oncologists. There seem to be no differences in presenting clinical features, immunophenotypic characteristics, or cytogenetic abnormalities for young adult ALL patients treated on paediatric or adult protocols with the exception of median age (16-paediatric trials versus 19-adult trials). There is no evidence to suggest that age within the 16-21 year old subgroup has any prognostic significance. Compared with patients 1-9 years, young adult ALL patients have a lower incidence of favourable cytogenetics t(12; 21) hyperdiploidy, a slightly increased incidence of the t(9;22), and an increased frequency of T cell immunophenotype. Compared with patients >30 years, young adult ALL patients have a significantly lower incidence of the t(9; 22). In multiple studies, there is a consistent, large event-free survival and survival advantage for young adult patients treated on paediatric versus adult protocols.