This pilot study aimed to investigate dietary changes introduced after being diagnosed with cancer in a sample of 60 consecutive children and adolescents on the basis of a self-report questionnaire. The study showed that 53% of patients changed their diet, usually "to combat the tumor" (in 47% of cases). In 1 in 2 of these cases, the health care staff were not informed about any changes. This study underscores the fact that many patients and families chose to impose dietary changes that are not always discussed with their health care staff and that may risk interfering with the continuity of a patient's treatment. It is essential to have more opportunities to speak with patients and families about this issue.