What Are the Risk Factors for Retinoblastoma?
A risk factor is anything that affects a person’s chance of getting a disease such as cancer. Different cancers have different risk factors.
Lifestyle-related risk factors such as body weight, physical activity, diet, and tobacco use play a major role in many adult cancers. But these factors usually take many years to influence cancer risk, and they are not thought to play much of a role in childhood cancers, including retinoblastomas.
There are very few known risk factors for retinoblastoma.
Most children diagnosed with retinoblastoma are younger than 3 years old. Most congenital or hereditary retinoblastomas are found during the first year of life, while non-inherited retinoblastomas tend to be diagnosed in 1- and 2-year-olds. Retinoblastomas are rare in older children and in adults.
About 1 out of 3 retinoblastomas is caused by a mutation (change) in the RB1 gene that is present in all the cells of the child’s body. But of these cases, only about 1 in 4 is inherited from one of the child’s parents. In the rest, the gene mutation is not inherited, but occurs during early development in the womb. Children born with a mutation in the RB1 gene usually develop retinoblastoma in both eyes. Regardless of whether the mutated RB1 gene was inherited from a parent or not, because these children have the mutated gene in all of their cells, they have a 1 in 2 chance of eventually passing it on to their children.
Most of the remaining 2 out of 3 retinoblastomas occur as a result of a random RB1 gene mutation that occurs only in one cell of one eye. These mutations are not inherited from a parent, and children who have them do not pass on a greatly increased risk of retinoblastoma to their children. Non-hereditary retinoblastomas always affect one eye only.
The way in which inherited gene changes make certain children likely to develop retinoblastoma is explained in the section “ Do we know what causes retinoblastoma?”
Last Medical Review: March 12, 2015 Last Revised: March 12, 2015