Retinoblastoma is a rare type of cancer found in the eye. In
retinoblastoma, one or more tumors form in the retina. The
retina is a layer of light-sensitive tissue that lines the back
of the eye. It converts visual images into nerve impulses in the
brain that allow us to see. If not treated, the tumors will
continue growing. The cancer may grow along the optic nerve and
reach the brain or it may travel to other parts of the body.
Cancer occurs when cells in the body (in this case retina cells)
divide without control or order. Normally, cells divide in a
regulated manner. If cells keep dividing uncontrollably when new
cells are not needed, a mass of tissue forms, called a growth or
tumor. Tumors can invade nearby tissue and spread to other parts
of the body. During early stages of fetal development, fast-
growing, immature cells called retinoblasts form. Later, these
cells become retinal cells. In retinoblastoma, some of these
cells quickly grow out of control. Some cases of the tumor are
inherited; others are