n WHAT CAUSES RETINOBLASTOMA? Retinoblastoma is caused by a mutation (mistake) in a gene that can occur sporadically (randomly) or be inherited from a parent.
n WHO GETS RETINOBLASTOMA? Retinoblastoma is a rare form of cancer that occurs once in every 12,000–34,000 live births. It makes up only 1%–3% of all childhood malignancies. Children who have a family history of retinoblas- toma have a much greater chance of developing the disease.
n IS RETINOBLASTOMA INHERITED? Retinoblastoma can be inherited but also can occur randomly. Children with bilateral retinoblastoma are born with a genetic change (called a mutation) that causes them to develop retinoblastoma early in life. These children are born with a genetic mutation (gene mistake) that may cause them to develop retinoblastoma during their first few years of life. Only 10% of all children with newly diagnosed bilateral retinoblastoma have a parent with a history of retinoblastoma. These children inherit the mutation from the parent with retinoblastoma. The other 90% do not have a parent with retinoblastoma; they develop the mutation in early development (during pregnancy). The cause of the mistake or mutation is unknown. The inherited form of retinoblastoma is diagnosed at a younger age and can occur in both eyes or with multiple (more than one) tumors in one eye. Children who have the inherited form of retinoblastoma can pass this cancer on to their own children; there is a 50% chance of retinoblastoma occurring with each pregnancy. Children who have unilateral (one affected eye) retinoblastoma with a single tumor usually do not have the inherited form. They have a 15% chance of having the inherited form and passing this cancer on to their children. Genetic testing (usually by taking a blood sample) is the only way to know for sure whether a single retinoblastoma tumor is inherited or not. When a child is diagnosed with retinoblastoma, the family usually is referred for genetic counseling. Genetic counselors work as members of a healthcare team, providing information and support to families who have a history of birth defects or genetic dis- orders and to those who may be at risk for a variety of inherited conditions. They investigate the health problems in the family, interpret information about the disorder, analyze inheritance patterns and risks of recurrence, and review available options with the family. Genetic counselors also provide supportive counseling to families, serve as patient advocates, and refer individuals and families to community or state support services when appropriate.
n WHAT ARE METASTASES? Metastases refer to spread of the tumor from its original location to other parts of the body. Retinoblas- toma can metastasize to other parts of the eye, the bones, bone marrow, spinal fluid, or the brain.
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