Risk of non-fatal self-injury among adolescent and young adult survivors of cancer: a population-based matched cohort study

Background — A diagnosis of cancer in an adolescent or young adult (AYA) can result in prolonged psychological distress, increasing the risk of depression and self-harm. While non-fatal self-injury (NFSI) rates shortly after diagnosis have been studied, little is known about these risks in long-term survivors of AYA cancer. This study examined the risk of NFSI among survivors of AYA cancer compared with matched cancer-free controls in Ontario, Canada.

Methods — This retrospective population-wide matched cohort study included all 5-year survivors of a first diagnosis of cancer between January 1, 1997, and December 31, 2016, who were aged 15–39 years at the time of primary diagnosis. They were 1:5 matched to cancer-free controls based on birth year, sex, and forward sortation area. To examine the association between survivorship and the risk of NFSI, adjusted Cox proportional hazards regression models were implemented, accounting for the matched design.

Results — The cohort consisted of 48,374 survivors and 241,870 matched cancer-free controls, with a median age at diagnosis of 33 years. After multivariable adjustment, the risk of NFSI was significantly higher among survivors than their corresponding matched controls within the first 5 years after reaching survivorship (adjusted hazard ratio, 1.15; 95% CI, 1.01–1.31; p = 0.029); no significant risk difference was found beyond 5 years.

Conclusion — AYA cancer survivors experienced increased risks of NFSI over the initial 5 years of follow-up. These findings highlight the importance of initiating long-term psychosocial surveillance and mental health support as early as possible in survivorship or even during cancer treatment.