Causes

Retinoblastoma occurs when nerve cells in the retina develop genetic mutations. These mutations cause the cells to continue growing and multiplying when healthy cells would die. This accumulating mass of cells forms a tumor.

Retinoblastoma cells can invade further into the eye and nearby structures. Retinoblastoma can also spread (metastasize) to other areas of the body, including the brain and spine.

For most instances of retinoblastoma, it's not clear what causes the genetic mutation that leads to cancer. However, it's possible for children to inherit a genetic mutation from their parents.

Retinoblastoma that is inherited

Gene mutations that increase the risk of retinoblastoma and other cancers can be passed from parents to children.

Hereditary retinoblastoma is passed from parents to children in an autosomal dominant pattern, which means only one parent needs a single copy of the mutated gene to pass the increased risk of retinoblastoma on to the children. If one parent carries a mutated gene, each child has a 50% chance of inheriting that gene.

Although a genetic mutation increases a child's risk of retinoblastoma, it doesn't mean that cancer is inevitable.

Children with the inherited form of retinoblastoma tend to develop the disease at an earlier age. Hereditary retinoblastoma also tends to occur in both eyes, as opposed to just one eye.