Retinoblastoma

Introduction
This is the most common primary tumor of the eye in children. It arises from the retina. .The retina is a layer of nerve tissue that coats the back of the eye, which is important for vision of person. Retinoblasts (immature cells of the retina) multiply during gestation and early life, to make enough cells to create the retina. As child grows, these cells mature & no longer differentiate. If these immature retinoblasts turn into cancer cells, retinoblastoma develops, the cause of which is unknown. The gene responsible is RB1 gene.

Incidence:
The annual incidence is one in 20000 children. It occurs most often in children under 4 years of age.

Types:
Hereditary:
•Hereditary form of Retinoblastoma occurs in 40%.
•May have more than one tumor
•Tumor often affects both eyes
•May have tumors in other parts of the body
•At increased risk for other cancers later in life

Non-hereditary:
•Most children with retinoblastoma (60%) do not have the genetic form.
•They develop tumor in only one eye i.e. unilateral.
•These children do not have an increased risk of developing other cancers.
•Their offspring have the same risk of developing retinoblastoma as other children in the population.

Symptoms:
•A pupil that looks white or red instead of the usual black i.e. called as white or cat’s eye reflex.
•A crossed eye i.e. strabismus.
•Poor vision
•A red, painful eye
•An enlarged pupil
•Differently colored irises

Investigations:
•Examination under general anesthesia using Retcam
•Ultrasound
•CT (CAT) scan
•MRI
•CSF examination
•Bone marrow studies
•Bone scan in advanced disease
•Chromosomal analysis (in certain cases)

Management:

1.Surgery to remove the eye, known as enucleation. This s done when there is no vision in eye to save further spread & life. Enucleation may also be recommended if the tumor does not respond to treatment.

2.Chemotherapy is used to shrink tumors in the eye. This approach is often used in children with bilateral disease (both eyes) for saving at least one eye which has less disease. It is also used in small tumors where the eye vision is present to save the eye. in combination with other measures such as

1.Photocoagulation--using laser light to destroy blood vessels supplying the tumor.
2.Thermotherapy--using heat to destroy tumor cells
3.Cryotherapy--using extreme cold to destroy tumor cells
4.Radiation Therapy—It is used for control of local disease with preservation of vision. Radiation plaque therapy and particle beam radiotherapy are used frequently.

Prognosis:
The five-year survival rate for children with retinoblastoma is more than 90%.