The non-Hodgkin lymphomas (NHLs) occurring in children and adolescents and young adults (AYA) are characterized by various age-related differences in tumor biology and survival. Children generally present with high-grade lymphomas, such as Burkitt lymphoma, diffuse large B-cell lymphoma, lymphoblastic lymphoma, and anaplastic large cell lymphoma, whereas low-grade histologic subtypes, such as follicular lymphoma, occur more frequently with increasing age. Treatment outcome for children with NHL

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... is generally superior to that observed in adults. Factors contributing to this discrepancy include psychosocial factors, patient factors, and differences in tumor biology and therapy. These factors will be reviewed, with particular attention to the biological features of diffuse large B-cell lymphoma and anaplastic large cell lymphoma and corresponding therapeutic challenges. Novel targeting agents have been developed, which have been shown to be active in some patients. There is clearly a need for treatment protocols with eligibility criteria that cover the full span of the pediatric and AYA age range and that incorporate detailed molecular characterization of the tumors. Learning Objectives • To describe age-related biological differences in NHL occurring in the pediatric and AYA population (ages 1-39) • To describe current treatment approaches for NHL in children and adults, and to identify ongoing challenges in determining optimal treatment approach for the AYA population Patient factors. There are certain age-associated patient/host factors that can influence treatment outcome. The International Prognostic Index (IPI), which includes the patient's performance status, has been shown to have significant prognostic value for adults with NHL. 10 Although components of the IPI, such as lactate dehydrogenase (LDH), may have prognostic significance in children, performance status is not routinely used in planning therapy for those with newly diagnosed NHL in the pediatric age group. However, there are some inherited immunodeficiency conditions, such as ataxia-telangiectasia and X-linked lymphoproliferative syndrome, where specific treatment modifications need to be incorporated. Age-related pharmacokinetic challenges must be considered in treatment planning. In this regard, drug clearance may vary with age and the maximum tolerated dose for many cancer agents is higher in younger patients. 11 An example of this is the inability of older patients