Academic achievements among siblings of children with cancer in Sweden: a nationwide register-based cohort study

Introduction The diagnosis of childhood cancer disrupts family dynamics and routine, potentially causing increased family stress and difficulties in maintaining academic commitments for the healthy sibling. Research evaluating siblings’ academic performance following a child’s cancer diagnosis is scarce. Thus, this study aimed to examine the impact of childhood cancer on academic performance in their cancer-free siblings. Methods By accessing nationwide registers and data on school grades, this study included 2,148 cancer-free siblings (born 1972–2002) to cancer-affected children (diagnosed 1997–2016) and 7,571 matched comparisons, matched on type of sibling (full/half sibling), country of birth (Sweden/abroad), siblings’ sex, siblings’ birth year and birth month, cancer-affected child’s birth year and birth month, maternal and paternal highest education. “Poor academic performance” was defined as the lowest 25th percentile of grades per year and the grades were set between 1989 and 2018. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression. Results Compared to individuals whose siblings did not have cancer, individuals having a sibling with childhood cancer did not affect their academic performance with an OR of 1.04 (95% CI = 0.92–1.17). However, in an exploratory subgroup analysis, individuals who had their academic grades assessed in the same year as their sibling’s cancer diagnosis had a numerically higher, but not statistically significant, odds ratio for poor academic performance (OR 1.32, 95% CI 0.97–1.80). Conclusion We found no significant association between childhood diagnosis and academic achievement in their healthy siblings. However, the impact needs to be addressed in further studies with larger sample sizes. Our exploratory finding of a numerically higher estimate for siblings graded in the same year as the diagnosis is hypothesis-generating and should be examined in larger studies.