Retinoblastoma is a cancer that forms in the tissues of the retina, the nerve tissue that lines the inside of the back of the eye. Although retinoblastoma may occur at any age, it usually occurs in children younger than 5 and most often in those younger than 2.
The cancer may be in one eye (unilateral) or in both eyes (bilateral). Retinoblastoma rarely spreads from the eye to nearby tissue or other parts of the body. Retinoblastoma occurs in heritable and nonheritable forms. After diagnosis and treatment in a child with heritable retinoblastoma, new tumors may continue to form for a few years. Most cases of retinoblastoma, however, are the nonheritable form. Treatment for both forms of retinoblastoma should include genetic counseling.
Retinoblastoma is a relatively uncommon tumor of childhood, accounting for about 3 percent of the cancers occurring in children younger than 15.Retinoblastoma Treatment (PDQ®)
Source: National Cancer Institute