Background: Ependymoma is the third most common pediatric central nervous system tumour. Treatment approaches are intensive and may include surgery, radiation, and chemotherapy. There are no longitudinal population-based cohort studies evaluating the long-term medical and functional outcomes of survivors of childhood ependymoma. Methods: Using a provincial pediatric cancer registry, all 5+ year ependymoma survivors diagnosed between 1987-2015 in Ontario, Canada were identified and matched to cancer-free population controls based on age, sex, and geographical location. Cases were followed from the index date (5 years from latest of diagnosis, or relapse/subsequent malignancy prior to age 18 years) until December 31, 2020 or censorship (death, or relapse/ new cancer after age 18 years). Clinical data were linked to administrative health databases to estimate the cumulative incidences and cause-specific hazard ratios (HR) of mortality, hospitalizations, strokes, hearing loss requiring a hearing aid, receipt of homecare services, and subsequent malignant neoplasms (SMNs) between cohorts, accounting for matching and competing risks. Results: Of 166 ependymoma diagnoses in the study period, 70 (42.2%) were excluded, most commonly due to early death prior to the index date. Ninety-six cases were matched to 480 controls (Table). The 10-year survival probability after the index date was 92.8% in cases and 99.6% in controls (HR 9.3, 95% CI 2.3-45.2, p=0.002). Compared to controls, cases were at higher risk of hospitalization (HR 3.2, 95% CI 2.2-4.6, p<0.0001), stroke (HR 33.3, 95% CI 5.7-629.1, p<0.0001), and receiving homecare services (HR 4.1, 95% CI 2.5-6.5, p<0.0001). Cases were at high risk of hospitalizations, strokes, hearing loss, and SMNs, with cumulative incidences of 64.7% (95% CI 46.6-78.0), 9.7% (95% CI 3.4-19.9), 13.5% (95% CI 5.3-25.5), and 12.8% (95% CI 4.7-24.9) at 20-years post index date, respectively. Conclusions: As survival of pediatric ependymoma improves, establishing the burden of late morbidity is critical. Dedicated screening programs for late sensory and neurovascular sequelae are warranted, as are interventions during and following treatment to mitigate the risk of developing such complications.

–: not applicable; IQR: interquartile range.