Retinoblastoma

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Retinoblastoma: Cancer of the Eyes
Retinoblastoma is the most common intraocular malignancy of infancy and childhood. Before this century, retinoblastoma was a fatal disease. The introduction of the ophthalmoscope, general anesthesia, and surgical enucleation has improved the situation. Today, the survival rate exceeds 90% in most industrialized countries. Retinoblastoma represents the phenotypic expression of an abnormal or absent tumor suppressor known as the retinoblastoma gene (RB1). The RB1 gene is found on the thirteenth chromosome The tumor develops from the immature retina. There are both hereditary and non-hereditary forms of retinoblastoma. In the hereditary form, multiple tumors are found in both eyes, while in the non-hereditary forms of retinoblastoma, only one eye is affected by only one tumor.
Prior to the knowledge of the RB1 gene, children with retinoblastoma were classified as having either sporadic or inherited retinoblastoma. Clinically and histologically, inherited and sporadic tumors are indistinguishable from one another. Markers for the inherited variety include bilateral involvement and multifocal primary tumors in one eye. The absence of multiple tumors, however, does not exclude the possibility of inherited retinoblastoma. Historically, the retinoblastoma trait seemed to be transmitted in an autosomal dominant pattern. On occasion, a family will demonstrate a skipped generation indicating genetic carriers.
There is no predisposition for retinoblastoma by race or gender. Right and left eyes are affected equally. The incidence of retinoblastoma worldwide ranges from 1 in 14,000 live births to 1 in 34,000. In the United States, the incidence has remained the same from 1974 to 1985. Of three national population-based studies in the United States, the latest and largest study reported 220 cases from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute. The average...