Retinoblastoma: Symptoms, Causes, Testing, Treatment
Synopsis: A retinoblastoma is a form of childhood cancer that starts from immature retinal cells in one or both of the person's eyes. Retinoblastoma is a rare tumor, accounting for approximately three percent of all cancers in children under fifteen. The tumors start in the retina, the light-sensitive layer of the person's eye that enables them to see. Each year in America, it is estimated that approximately ten to fourteen million children between the ages of birth and four years of age experience retinoblastoma.
Retinoblastoma is a form of childhood cancer that starts from immature retinal cells in one or both of the person's eyes and may begin from the time a child is still in the mother's womb until they are five years of age. The form of cancer is curable if it is caught early enough. Eighty-seven percent of children with this form of cancer worldwide perish from it, most in developing nations. In developed countries, ninety-seven percent of children with retinoblastoma who survive live with moderate to severe visual impairments.
The U.S. Social Security Administration (SSA) has included Bilateral Retinoblastoma as a Compassionate Allowance to expedite a disability claim.
Retinoblastoma is a rare tumor, accounting for approximately three percent of all cancers in children under fifteen. The tumors start in the retina, the light-sensitive layer of the person's eye that enables them to see. Tumors present in one eye are referred to as 'unilateral retinoblastoma.' When they are present in both of the person's eyes, they are referred to as 'bilateral retinoblastoma.' Nearly sixty percent of the people who experience retinoblastoma have unilateral retinoblastoma, with the remainder experiencing bilateral retinoblastoma. Around ninety percent of people with retinoblastoma do not have a family history of the disease; the remaining people newly diagnosed have family members with retinoblastoma.
Each year in America, it is estimated that approximately ten to fourteen million children between the ages of birth and four years of age experience retinoblastoma. While ninety-five percent of children with this form of cancer are diagnosed before age five, people with retinoblastoma who are diagnosed after age five tend to have a poorer diagnosis. Retinoblastoma is a tumor that occurs in both heritable and non-heritable forms. The heritable form of the disease includes people with positive family history and those who have sustained a new mutation at the time of conception. The fact that retinoblastoma is usually confined to the person's eye finds more than ninety percent of children with it being cured. The current challenge from a medical standpoint is the treatment of retinoblastoma while preventing loss of the person's eye, blindness, or other serious effects as a result of treatment for the disease that may reduce the person's lifespan or quality of their life.
Causes of Retinoblastoma
The heritable retinoblastoma can manifest in either the unilateral or bilateral form of the disease. Most unilateral diseases are not heritable, although children with bilateral are presumed to have the inheritable form of the disease. Infants with unilateral tumors are more likely to have the inheritable form of retinoblastoma, while older children with unilateral tumors are more likely to have the non-heritable form. Young children with unilateral tumors have fewer genetic abnormalities than older children. Children with heritable retinoblastoma with average eye examination results in at least one eye need to be re-examined frequently for the potential development of new tumors, approximately every two to four months for at least twenty-eight months. After receiving treatment, people with retinoblastoma require eye examinations until they reach age five.
'Trilateral' retinoblastoma is a well-recognized syndrome of unilateral or bilateral heritable retinoblastoma associated with an intracranial neuroblastic tumor. Approximately five to fifteen percent of children with multi-focal, familial, or bilateral retinoblastoma might develop an intracranial neuroblastic tumor. Children with the heritable form of retinoblastoma also have an increased risk of trilateral retinoblastoma, which is associated with a poor prognosis. Intensive therapy forms currently under development may offer some promise for children with this form of retinoblastoma.
In a study of nine hundred and sixty-three people who were at least one year survivors of hereditary retinoblastoma in America between 1914 and 1984, risks were elevated for soft tissue sarcoma overall, with leiomyosarcoma being the most frequent subtype. Seventy-eight percent of leiomyosarcomas are diagnosed thirty or more years after the person received a diagnosis of retinoblastoma. The risks were elevated in people whether or not they were treated with radiation. In people who did receive radiation therapy, sarcomas were found both within and outside of the area of radiation treatment. What this suggests is that there may be a genetic predisposition to soft tissue sarcoma in some people.
There is a notable increase in mortality due to bladder, lung, and other epithelial cancers in people with heritable retinoblastoma who did not receive radiation therapy. Tobacco use is associated with these forms of cancer in this population. Carcinogenic effects of radiation increase with the dose administered, particularly for secondary sarcomas. In people who have received radiation therapy, two-thirds of the secondary cancers have occurred within the irradiated tissues, and one-third occurred outside of the irradiated tissues. The risks increase depending on the person's age at the time radiation therapy is administered, with the risk being less for people who are older than twelve months.
Symptoms of Retinoblastoma
Common signs of retinoblastoma include a white glow or glint in the pupil of one or both of the person's eyes in dim lighting, a white pupil in a color photograph, or crossed or misaligned eyes. If you notice a white glow in any of your children's pictures, contact a pediatrician or an ophthalmologist promptly and have their eyes examined. Ask them to dilate both of your child's eyes. If the doctor is unwilling or unable to dilate your child's eyes, seek another doctor.
While it is rare, retinoblastoma may spread or 'metastasize' outside a person's eye and into their brain, central nervous system, or bones. When this happens, chemotherapy is prescribed by a pediatrician specializing in oncology. It is administered through the child's peripheral blood vessels or into their brain for months or years after diagnosis.
Siblings of people with retinoblastoma need to have regular ophthalmic exams. Studies suggest that DNA polymorphism analysis can assist in predicting who is at risk. Genetic counseling should be a part of the therapy a person with retinoblastoma receives, whether they have the unilateral or bilateral form of the disease. Ten to eighteen percent of children with retinoblastoma have somatic genetic mosaicism, which makes their genetic, 'story,' more complex and contributes to the difficulty of genetic counseling.
Exon by exon sequencing of the person's RB1 gene demonstrates germline mutation in around ninety percent of people with the heritable form of retinoblastoma. While a positive finding confirms susceptibility, a negative one does not rule it out. A multi-step assay includes DNA sequencing to identify mutations within coding exons and immediate flanking intronic regions, Southern blot analysis to characterize genomic rearrangements, and transcript analysis to characterize potential splicing mutations buried within introns. Expanded analysis shows promise in better defining the functional significance of seemingly novel mutations in pilot investigations. The RB1 gene is located within the q14 band of chromosome 13. The absence of detectable RB1 mutations in some people might suggest that alternative genetic mechanisms could underlie the development of retinoblastoma.
Treatment of Retinoblastoma
The kind of treatment a person requires depends on the extent of the disease within their eye and whether or not the disease has spread beyond their eye to their brain or other parts of their body. The risk of extraocular recurrence can be increased in the presence of pathologic sclera invasion and in people who need bilateral enucleation. People with retinoblastoma commonly have extensive disease in one eye when diagnosed, with either tumor involving more than half of their retina. These multiple tumors are diffuse and involve their retina or obvious vitreous seeding. People who have bilateral retinoblastoma should receive targeted, systemic therapy to treat the more severe eye. The therapy goals involve eradicating the disease, preserving the person's vision, and decreasing the risk of late sequelae from treatment.
People with retinoblastoma often experience a variety of long-term visual field defects after receiving treatment. The defects are related to the size of the tumor, its location, and the method of treatment administered. One study of visual acuity following treatment with systemic chemotherapy and focal ophthalmic therapy was conducted in forty children and involved fifty-four of their eyes. After a follow-up of sixty-eight months, twenty-seven of the children had a final visual acuity of 20/40 or better, while some had eyes with a final visual acuity of 20/200 or better. The clinical factors that predicted visual acuity of 20/40 or better were a tumor margin of at least 3 millimeters from the foveola and optic disk and an absence of sub-retinal fluid.
Systemic carboplatin is commonly used in the treatment of retinoblastoma. There has been some concern about hearing loss in this form of therapy. A recent analysis of one hundred and sixty-four children who received treatment with six cycles of carboplatin-containing therapy demonstrated no loss of hearing among children who had an average initial audiogram.
People who are asymptomatic when diagnosed with an intracranial tumor tend to have a better overall survival rate than people who experience symptoms. Screening through neuroimaging can improve their cure rate. One recommendation is that children with heritable retinoblastoma should be screened using magnetic resonance neuroimaging, or CT scans, every six months after being diagnosed until they reach the age of five. The use of chemotherapy to reduce the extent of intraocular tumors in people with bilateral retinoblastoma could prevent the development of pineal tumors.
Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursing Disability Studies. As a Nursing Assistant Thomas has assisted people from a variety of racial, religious, gender, class, and age groups by providing care for people with all forms of disabilities from Multiple Sclerosis to Parkinson's; para and quadriplegia to Spina Bifida.
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Cite This Page (APA): Thomas C. Weiss. (2010, March 4). Retinoblastoma: Symptoms, Causes, Testing, Treatment. Disabled World. Retrieved September 23, 2023 from www.disabled-world.com/disability/types/retinoblastoma.php
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