Long-term cognitive outcome in adult survivors of an early childhood posterior fossa brain tumour

Abstract

Purpose: Posterior fossa brain tumours (PFT) and their treatment in young children are often associated with subsequent cognitive impairment. However, reported follow-up periods rarely exceed 10 years. This study reports very long-term cognitive consequences of surviving an early childhood PFT.

Methods: 62 adult survivors of a PFT, ascertained from a national register, diagnosed before 5 years of age, and a sibling control, received a single IQ assessment an average of 32 years (range 18-53) after initial diagnosis, using the Weschler Abbreviated Scale of Intelligence. Regression models were fitted to survivor-sibling pair differences on verbal and performance IQ (VIQ and PIQ) scores to investigate whether increasing time between PFT diagnosis and follow-up IQ assessment contributed to survivor-sibling IQ differences.

Results: At follow-up, survivors had, on average, VIQ 15 points and PIQ 19 points lower than their siblings. There was no significant effect of time since diagnosis on survivor-sibling VIQ difference. Survivors who received radiotherapy showed no significant effect of time since diagnosis on survivor-sibling PIQ difference. Survivors who did not receive radiotherapy demonstrated a trend for it to reduce.

Conclusions: VIQ and PIQ deficits persist in adulthood, suggesting the effect of a fixed injury imposing on cognitive development, rather than an ongoing pathological process.

Implications for cancer survivors: The findings will help parents and others supporting survivors of an early life PFT to identify and plan for possible cognitive outcomes, and highlight the importance of early interventions to optimize cognitive function during the developmental period.

Keywords: Childhood brain tumour; Cognition; Posterior fossa; Survivorship.

Fig. 1

Flow chart of recruitment. Adapted from Carroll et al. [17]

Fig. 2

GAM smooth estimates for the relationship between time since diagnosis (years), while adjusting for all other covariates in the model in Table 3, and a verbal IQ (VIQ); b performance IQ (PIQ) among those with no confirmed radiotherapy; c PIQ among those with confirmed radiotherapy. The PIQ model includes an interaction between the smooth and radiotherapy, hence we have two smooths for PIQ b and c. The y-axis represents the difference between survivors’ and their siblings’ IQ scores; however, the difference shown must be combined with the effect of other covariates from Table 3 to be interpreted. Since survivor’s scores are, on average, lower than their siblings the difference in scores will be negative (survivor minus sibling will be less than zero); hence, a positive smooth value indicates the difference is decreased (ie survivors IQs are improving by getting closer to that of their siblings). Each panel includes a rug plot, showing the contributing participants/observations