Seasonal Variation in the Diagnosis of Retinoblastoma

Purpose: To determine the seasonal variation in the diagnosis of retinoblastoma in a global sample of children and to investigate predictors of seasonal trends. Methods: Data were collected through a global, multicenter, 1-year cross-sectional analysis that included all treatment- naïve retinoblastoma patients presenting to participating centers between January 1, 2017, and December 31, 2017. Due to variations in days per month, data were normalized to a 30-day/month calendar. Observed data were compared to a simulation study of expected results using a uniform distribution. Results: Patient-level data were available for 4,351 children from 276 centers in 153 countries, of which 3,966 had a month of presentation recorded. There were relative peaks in disease presentation in January and July, with lower counts in November and December (p = .0015). No covariates were found to be significantly associated with the seasonal trend. Two covariates, patient age at presentation and extraocular tumor spread, showed a moderate association with month of presentation. Conclusion: Our findings suggest seasonal trends in the presentation of retinoblastoma across the world. However, these trends do not appear to be related to income level of a country, climate, or other covariates. Any connection between seasonal variation of retinoblastoma presentation and retinoblastoma outcomes remains unclear or not present.