Overall survival and cause-specific mortality in a hospital-based cohort of retinoblastoma patients in São Paulo, Brazil.

ABSTRACT

Studies are lacking on long-term effects among retinoblastoma patients in low- and middle-income countries. Therefore, we examined cause-specific mortality in a retrospective cohort of retinoblastoma patients treated at Antonio Candido de Camargo Cancer Center (ACCCC), São Paulo, Brazil from 1986 to 2003 and followed up through December 31, 2018. Vital status and cause of death were ascertained from medical records and multiple national databases. We estimated overall and cause-specific survival using the Kaplan-Meier survival method, and estimated standardized mortality ratios (SMRs) and absolute excess risk (AER) of death. This cohort study included 465 retinoblastoma patients (42% hereditary, 58% nonhereditary), with most (77%) patients diagnosed at advanced stages (IV or V). Over an 11-year average follow-up, 80 deaths occurred 70% due to retinoblastoma, 22% due to subsequent malignant neoplasms (SMNs) and 5% to non-cancer causes. The overall 5-year survival rate was 88% consistent across hereditary and nonhereditary patients (p = .67). Hereditary retinoblastoma patients faced an 86-fold higher risk of SMN-related death compared to the general population (N = 16, SMR = 86.1, 95% CI 52.7-140.5), corresponding to 42.4 excess deaths per 10,000 person-years. This risk remained consistent for those treated with radiotherapy and chemotherapy (N = 10, SMR = 90.3, 95% CI 48.6-167.8) and chemotherapy alone (N = 6, SMR = 80.0, 95% CI 35.9-177.9). Nonhereditary patients had only two SMN-related deaths (SMR = 7.2, 95% CI 1.8-28.7). There was no excess risk of non-cancer-related deaths in either retinoblastoma form. Findings from this cohort with a high proportion of advanced-stage patients and extensive chemotherapy use may help guide policy and healthcare planning, emphasizing the need to enhance early diagnosis and treatment access in less developed countries.