Purpose: The purpose of this study was to describe and explore the experience of adolescents with cancer. Methods: This study was based on the grounded theory by Strauss & Corbin (1998). The subjects were 13 adolescents including in and out-patients of a university hospital diagnosed with cancer. Results: ‘Getting changed’ and ‘getting deviated’ were found to be the causal conditions. ‘Inclination’, ‘self-reliance’, and ‘hope’ were identified as contextual conditions, ‘shrinking feeling’ as the core phenomenon, ‘awareness of disease’, ‘self-consciousness’, and ‘getting understanding and love’ as intervening conditions, ‘negligence’, ‘separation’, ‘self-management’, and ‘inspiration’ as the strategies and ‘being shirk’, ‘getting back’, and ‘going forward’ as consequences. ‘Breaking out of the withdrawn ego’ was the core category in this study. Conclusion: This study provides a framework for the development of individualized nursing interventions for ‘Breaking out of the withdrawn ego’ to care for adolescents with cancer. Finally adolescents with cancer are ‘reborn’ with a more mature ego.