This anthropological study explores children's non-social reactions during the active treatment period, the on-treatment, in a paediatric oncology ward in a Danish university hospital. It is argued that, although some children's non-social reactions is a tactical disengagement to manage the on-treatment situation, such non-social tactics might ultimately prove an undesirable strategy with negative long-term social consequences for social survivorship. Data were generated over 7 months of ethnographic fieldwork between May 2011 and January 2013, using qualitative methods such as participant observation and open-ended interviewing. Fifty children of both sexes between 4 and 15 years, their families and hospital staff participated in the study. These data formed the basis for the study. The findings show that children's response to care challenges, including exhaustion from care management, exposure from being in a public space, and the open-ended duration of treatment, configure in tactic forms that we term social disengagement. It is suggested that such tactical social disengagement might expand into long-term social patterns, and, as such, change from an alleviating tactic to a socially isolating and damaging tactic for survivors of cancer in childhood.