Retinoblastoma is a childhood cancer of the retina that usually occurs before the age of 5. This is a very rare malignant tumor.
The retina is the lining of btheack of the eye. It is composed of specialized cells that capture light and color to allow us to see. When due certain carcinogenic factors there an uncontrolled growth of retinal cells, a form alteration of a gene called retinoblastoma gene (RB) occurs, which leads to development of retinoblastoma.
Incidence of Retinoblastoma
Retinoblastoma is considered a childhood cancer because 95% of cases occur in children under 5 years old. The tumor can appear in both eyes, and children of both sexes can be affected, regardless of race. Half of the cases is diagnosed before the age of two years and 45% affecting both eyes before the age of 15 months. The incidence of retinoblastoma varies between 3 and 50 per million children under 14 years old
Causes of Retinoblastoma
Body cells recur throughout life. Old cells die and replaced by new ones in an orderly manner by a natural process called apoptosis, programmed cell death. This is natural and vital to keep the body healthy. Like all cancers, retinoblastoma occurs when this regulatory mechanism is disrupted and the cells begin to divide at an abnormally fast rate.
Although the exact causes are not known, scientists group retinoblastoma causes in two main categories: those attributable to a defective gene transmitted by heredity, hereditary retinoblastoma; andthose caused by a random accidental change from the RB gene during cell replication, sporadic retinoblastoma.
Sporadic process is the main cause of retinoblastoma. About 90% of children with this disease have no family history of the tumor, while children whose one parent was affected represent less than 10%of diagnosed cases. In general, retinoblastomas affecting one eye do not have anyhereditary connection while those touching both eyes are almost always hereditary.
Researchers have not yet determined with certainty the causes of genetic mutation that leads to retinoblastoma, but they know certain factors that increase the risk.
Family history is the main risk factor for retinoblastoma. Children who inherit the altered gene are at 90% risk of having the disease. Although controversial, human papillomavirus (HPV) also seems to increase the risk for retinoblastoma.
Symptoms of Retinoblastoma
Retinoblastoma symptoms can be easily recognized, although only a health professional can confirm the diagnosis. In fact, the tumor is detected first by a family member or friend in 80% of cases, while less than 20% of cases are by a doctor. It is often difficult for parents to determine if their child has retinoblastoma because, given the age of the child cannot express himself to explainproblems. The best thing is for parents or the care giver of the child to look for unusual signs suggesting retinoblastoma. Early detection and diagnosis are important to improve the healing or survival chance, up to 90% to 95%. At the beginning, look for these typical signs in your childand report them to your physician as soon as possible:
- Leukocoria (white pupil) – a condition which causes the pupil (the round hole in the colored part of the eye) to become white rather than remains black as usual.
- Strabismus(heterotropia or as crossed eyes)– this happens when one eye does not seem to look at the target, the deviation can be convergent or divergent type.
However, as the tumor progress in the retina, the vision of the child can be seriously damaged. Partial or total blindness in one eye or both eyes can occur. For most children, retinoblastoma develop in one eye; however, the cancer can spread to the other eye or other body parts, particularly the brain, lungs, and bones. Metastasis or the spread of this cancer is rare. Whenmetastatic retinoblastoma occurs, it usually happens 1-2 years after treatment of the primary tumor.
Only a health care professional can diagnose retinoblastoma based on the symptoms and diagnostic tests. If clinical signs suggest the presence of the tumor, the doctor will use specialized equipment to look inside the eyes of the child. But imaging tests such as computed tomography or magnetic resonance imaging (MRI) are required to confirm the diagnosis. In general, a biopsy (tissue sample)of the eye is not indicated because it can damage the eye unnecessarily
There are several retinoblastoma treatment options. The choice depends on the severity of the cancer and the type of retinoblastoma treated, whether it is inherited or not. If the physician believes the patient will not lose his vision, he will propose laser therapy or cryotherapy to freeze the cancer cells.
Among the non-surgical options, radiation therapy is a treatment of last resort because of its potential side effects, or possible destruction of healthy tissue. In fact the radiotherapy itself may trigger new non-ocular tumors in hereditary cases. Chemotherapy is sometimes used to reduce the tumor volume before resorting to other treatments.
Surgical removal of the eye (Enucleation) is practiced in rare severe cases when the vision of the child cannot be preserved or if there is a high risk of the cancer will spread.