Retinoblastoma in Kazakhstan: Incidence Trends and Survival Analysis (2015-2024)

Retinoblastoma (Rb) is a rare but aggressive pediatric eye cancer. This study aimed to examine its epidemiological characteristics, diagnostic stages, and survival factors in Kazakhstan, where national-level data have previously been limited.

A retrospective national registry study was conducted using data from the Scientific Center for Pediatrics and Pediatric Surgery, the country's referral center for Rb (2015-2024). Incidence was calculated using a birth cohort approach per 100,000 live births. Demographic and clinical characteristics, including diagnostic intervals (lag time 1: symptom onset to diagnosis; lag time 2: diagnosis to treatment initiation), were analyzed. Survival was estimated using Kaplan-Meier methods. Prognostic factors were assessed using univariate and multivariable Cox proportional hazards regression.

A total of 167 cases were recorded. The cumulative birth cohort incidence was 4.18 per 100,000 live births (1:23,915). Median age at diagnosis was 14 months (IQR: 6.5-27.5). Unilateral disease occurred in 78.4% of patients, and 76.9% were diagnosed at advanced stages (D or E). Extraocular involvement was observed in 9.8% of affected eyes. Hereditary Rb accounted for 6% of cases. Median lag time 1 was 60 days (IQR: 30-120), and median lag time 2 was 12 days (IQR: 7-20). Overall mortality was 11.4%, with most deaths occurring within 18 months. Older age at diagnosis (adjusted HR: 1.031; 95% CI: 1.008-1.054; p = 0.009) and longer lag time 2 (adjusted HR: 1.006; 95% CI: 1.004-1.008; p < 0.001) were independently associated with increased mortality.

Rb in Kazakhstan remains characterized by a high proportion of advanced-stage disease and measurable early mortality. Delays in treatment initiation and older age at diagnosis independently predict poorer survival, underscoring the need to strengthen early detection and optimize care pathways.