Lymphoma in Adolescents and Young Adults.

Lymphomas are one of the commonest malignancies in adolescents and young adults (AYA) accounting respectively for 22% of all cancers in patients aged 15-24 years (16% for Hodgkin lymphoma (HL) and 6% for non-HL (NHL)). The distribution of NHL subtypes in this age group differs strikingly from the distribution in children and in older adults with 4 main subtypes accounting for the majority of the cases: diffuse large B-cell lymphoma (DLBCL) including primary mediastinal B-cell lymphoma, Burkitt lymphoma, lymphoblastic lymphoma or anaplastic large cell lymphoma. Age-related differences in tumor biology have been demonstrated mainly in DLBCL but there is still a need for biological studies to better understand age-related differences in this age group. AYA patients currently diagnosed with HL and NHL have 5-year survival expectations exceeding 90 and 75%, respectively. Different therapeutic strategies are often used in children and adult lymphoma and the dispersion of lymphoma care between adult and pediatric hematologist-oncologists results in heterogeneous strategies for each subgroup according to age. The impact of these different strategies on outcomes is not easy to evaluate given the paucity of population-based data focused on this age group, taking into account tumor biology and the lack of a uniform staging system. Given the excellent results obtained with current therapies, the challenge now is to develop strategies aimed at reducing acute and long-term toxicity in most patients while maintaining high cure rates and to identify patients at high risk of failure requiring new strategies including more selective targeted therapies.