Rare tumours

Cancer is rare in childhood, compared to older age groups, affecting approximately 1 in 600 children during the first 15 years of life. How-ever, some paediatric malignancies are so rare that even paediatric oncologists only encounter them once in their lifetime practice. For this chapter, rare tumours in childhood are arbitrarily defined as those that have an age-standardized annual incidence (ASR) of less than one per million children in Great Britain. This chapter cannot cover all rare tumours in childhood, but will focus on those that only occur in children outside the central nervous system and currently have a poor prognosis. Also included is nasopharyngeal carcinoma, which more recently has had an improved prognosis, but still poses treatment challenges.