Neuroblastoma in adolescents: genetic and clinical characterisation

Age at diagnosis is an important risk factor in neuroblastoma (NB) with worse prognosis in children older than 18 months. A more indolent course with long-term relapses and fatal outcome has been described in small series of adolescents. Our objective was to describe biological factors that contribute to this particular behaviour and could be helpful in their treatment.

NB cases older than 10 years of age at diagnosis registered in the files of the Neuroblastoma Group of SEOP from 1992 to 2007 were included. Disease extension was classified according to the International Neuroblastoma Staging System (INSS). Tumour samples were studied according to the International Neuroblastoma Pathology Classification (INPC). Biological studies included MNA, 1p, 11q and 17q status and ploidy.

Twenty-two patients, from 10.1 to 24.6 years old, were included. Advanced stages predominated. 14/17 patients presented unfavourable histology. None had NMA or 1p del. However, 11q del was found in 8/13 cases and 17q gain in 7/11. Overall survival (OS) and event-free survival (EFS) for the entire series at 5 years were 0.45 and 0.32, respectively. Moreover, 5-year OS and EFS for stage 4 patients were 0.33 and 0.15.

NB in adolescents is a special subgroup characterised by high-risk prognostic features which differ from those seen in younger patients, especially in relation to genetic abnormalities. The outcome in stage 4 was worse than in younger metastatic children, outlining the need for new therapeutic approaches in this subgroup of patients. The exact cut-off to separate older patients has not yet been established and will probably be based on biology.