ON THIS PAGE: You will find out more about the factors that increase the chance of developing this type of cancer. To see other pages, use the menu on the side of your screen.
A risk factor is anything that increases a person’s chance of developing cancer. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do.
Currently, the only known cause of retinoblastoma is a genetic mutation or change. This genetic form of retinoblastoma accounts for about 40% of cases and always occurs in very young children, typically one year old or younger. When retinoblastoma affects both eyes, it is always a genetic condition. Despite the genetic link, only 10% to 15% of children with retinoblastoma have a family history of the disease. Rarely, the genetic form occurs in only one eye.
Children who have had bilateral retinoblastoma or the hereditary form of unilateral retinoblastoma are at increased risk for developing other types of cancer. The risk of an additional tumor is higher for children who receive radiation therapy to the orbit (eye socket) to preserve vision or to other parts of the body where the tumor has spread. If a newborn has a family history of retinoblastoma, the baby should be examined shortly after birth by an ophthalmologist who is experienced in treating cancers of the eye. An ophthalmologist is a medical doctor who specializes in eye care.
About 60% of children with retinoblastoma do not have the genetic form. They develop a single tumor in only one eye, and they have no increased risk of an additional tumor later in life.
The next section in this guide is Symptoms and Signs  and it explains what body changes or medical problems this disease can cause. Or, use the menu on the side of your screen to choose another section to continue reading this guide.