Reese, Ellsworth, and the Classification of Retinoblastoma.

Background: This review explores the development and legacy of the Reese-Ellsworth classification system for retinoblastoma, a landmark achievement in pediatric oncology. Summary: We first highlight the history of cancer staging in the early 20th century. Then, we discuss the lives of Algernon B. Reese and Robert M. Ellsworth, two pioneering figures in ophthalmic oncology, and their development of the Reese-Ellsworth classification system in 1963. The system served as the international standard for over 3 decades, stratifying patients by prognosis and enabling standardized treatment protocols and collaborative research that contributed to dramatic improvements in retinoblastoma survival rates. However, as the standard of care shifted from radiation to chemotherapy in the latter half of the 20th century, the system became obsolete and was ultimately replaced. Key Messages: The story of Reese and Ellsworth exemplifies how disease staging systems must adapt to changing therapeutic paradigms while demonstrating the importance of standardized classification in advancing cancer research.