Background: Long-term survivors of childhood cancer are at risk for fatigue, sleep problems, and neurocognitive impairment, although the association between these outcomes has not been previously examined.
Methods: Outcomes were evaluated in 1426 survivors from the Childhood Cancer Survivor Study using a validated Neurocognitive Questionnaire. Relative risks for neurocognitive impairment were calculated using demographic and treatment factors, and survivors' report on the Functional Assessment of Chronic Illness Therapy-Fatigue, the Short Form-36 Vitality Scale, the Pittsburgh Sleep Quality Index, and the Epworth Sleepiness Scale.
Results: Neurocognitive impairment was identified in >20% of survivors, using sibling-based norms for comparison. Multivariate logistic regression models revealed that fatigue (risk ratio [RR], 1.34; 95% confidence interval [CI], 1.13-1.59), daytime sleepiness (RR, 1.68; 95% CI, 1.55-1.83), poor sleep quality (RR, 1.23; 95% CI, 1.01-1.49), and decreased vitality (RR, 1.75; 95% CI 1.33-2.30) were all associated with impaired task efficiency. Likewise, fatigue (RR, 1.77; 95% CI, 1.23-2.55), sleepiness (RR, 1.38; 95% CI, 1.14-1.67), and decreased vitality (RR, 3.08; 95% CI, 1.98-4.79) were predictive of emotional regulation problems. Diminished organization was associated with increased sleepiness (RR, 1.80; 95% CI, 1.31-2.48) and decreased vitality (RR, 1.90; 95% CI, 1.37-2.63). Impaired memory was associated with poor sleep quality (RR, 1.45; 95% CI, 1.19-1.76), increased sleepiness (RR, 2.05; 95% CI, 1.63-2.58), and decreased vitality (RR, 2.01; 95% CI, 1.42-2.86). The impact of fatigue, sleepiness, sleep quality, and vitality on neurocognitive outcomes was independent of the effects of cranial radiation therapy, steroids and antimetabolite chemotherapy, sex, and current age.
Conclusions: Neurocognitive function in long-term survivors of childhood cancer appears particularly vulnerable to the effects of fatigue and sleep disruption. These findings suggest sleep hygiene should be emphasized among survivors, as it may provide an additional mechanism for intervention to improve neurocognitive outcomes.
Keywords: Childhood Cancer Survivor Study; fatigue; neurocognitive; sleep; vitality.
Copyright © 2010 American Cancer Society.