Why does retinoblastoma occur in children and not adults?

Retinoblastoma primarily occurs in children due to genetic mutations that affect the development of retinal cells, often involving the RB1 gene. These mutations can be inherited or occur spontaneously, leading to uncontrolled cell growth in the developing retina. In adults, the retinal cells are fully developed and typically do not undergo the rapid proliferation seen in childhood, making retinoblastoma much less likely. Additionally, most adult cancers arise from different mechanisms and have different risk factors than those associated with childhood cancers.