Risk of Renal or Urinary Related Hospitalization in Survivors of Childhood Cancer: Results from the French Childhood Cancer Survivor Study.

BACKGROUND: Hospitalization rates can be used as an indirect indicator of the burden and severity of adverse health outcomes in childhood cancer survivors (CCS). We aimed to determine the long-term risks of hospitalization related to renal and urinary diseases among 5-year CCS. METHODS: The French Childhood Cancer Survivor Study cohort was linked with data from the French National Healthcare System database, which enabled the identification of hospitalizations related to renal or urinary diseases. Clinical and detailed treatment data were collected from medical records. Dose-volume histograms were estimated for all patients treated with radiotherapy. Standardized Hospitalization Ratios and absolute excess risks (AER) were calculated. Relative risks were estimated using Poisson regression. RESULTS: A total of 5,498 survivors were followed for 42,118 person-years (PY). Survivors experience 2.9 times more renal hospitalizations than expected in the general population, with an AER of 21.2/10,000 PY. Exposing more than 10% of the kidneys' volume to at least 20 Gray increases the risk of being hospitalized for renal causes by 2.2 (95% confidence interval, 1.3-3.6). Nephrectomized survivors treated with high doses of ifosfamide (>60 g/m²) have an extremely high risk of hospitalization for renal causes. Patients with comorbidities have about a 3-fold higher risk, and nephrectomized patients a 2-fold higher risk of being hospitalized for renal causes compared with other subjects. In the case of hospitalization for urinary causes, treatment by anthracycline administration was found to be associated with an almost 2-fold higher risk of hospitalization compared with the general population. CONCLUSIONS: These results support the need for careful monitoring of long-term renal diseases in survivors who have undergone nephrectomy, those treated with high doses of radiation (≥20 Gy) even to small volumes of the kidneys, and those with predisposing risk factors. IMPACT: This study provides new evidence with potential impact on surveillance guidelines related to dose-volume indicators associated with renal toxicity.