Objectives: This paper offers an overview of the findings of research into the experience of having cancer in adolescence and young adulthood, the aims of which were to understand how age and life stage affect the illness experience and impact upon biographies and life trajectories. Methods: The data were gathered primarily through the use of in-depth qualitative interviews with adolescents and young adults with cancer, but also through the submission of a small number of written narratives. Results: Acute and life-threatening illness at a transitional life stage on the threshold of adulthood can have a long-term, and therefore chronic, effect on the life trajectories and biographies of young adult cancer patients. Many aspects of the participants' lives were affected, including education, careers, life plans, friendship networks, appearance, sexuality and fertility. The economic effects could also be far-reaching and contribute to a loss of independence, which is very fragile in this age-group. Conclusions: While recognizing the potentially devastating impact of cancer at any age, the research findings suggest a distinct effect in adolescence and young adulthood resulting from a disrupted biography at a critical transitional moment in the life trajectory that can have a chronic effect after the acute stage of the illness is passed. An age-appropriate approach to the care of young people with cancer that takes into account the distinct effects of life stage in this age-group can mitigate the negative impact on life trajectories and maximize the chances of adherence and a return to normal life after recovery.