Cancer in AYA is rare and treatment outcomes are often poorer than in paediatric patients with the same cancer. The type of tumours, their biology and sensitivity to current therapies, as well as the low participation of AYA in clinical trials affect the treatment results. AYA have specific and unmet needs, including complex psychological and social supportive care.The ESMO / SIOPE joint Working Group on Cancer in Adolescents and Young Adults (AYA) created a guideline to increase awarness amongst the medical and paediatric oncology communities and enhance knowledge on specific cancer issues in adolescents and young adults.