Diagnosing

Overview

Retinoblastoma is a cancer of the retina, the light-sensitive layer at the back of the eye. It is the most common eye cancer in children and usually appears before the age of five. It can affect one eye or both.

Causes

Retinoblastoma is caused by changes in both copies of the RB1 gene in a retinal cell.

Heritable retinoblastoma (about 40%) — the child is born with one changed copy in every cell; tumors often affect both eyes and can be passed on to children.
Non-heritable retinoblastoma (about 60%) — both changes happen only in the eye; it affects one eye.

Risk factors

A family history of retinoblastoma. Brothers and sisters of affected children, and the children of survivors, need regular eye checks from birth.

Symptoms

A white reflection in the pupil (leukocoria), often seen in flash photographs
A squint (crossed or wandering eye)
A red, painful or swollen eye
Poor vision

A white glow in a child's eye in photographs should always be checked by an eye doctor.

Stages

Tumors inside the eye are grouped (A to E) by size and spread within the eye; staging also describes spread beyond the eye.

Prognosis

When found early and treated at a specialized center, more than 95% of children survive, and in many cases the eye and useful vision can be saved.

Diagnosis is made by a specialist eye examination; a biopsy is not performed because it could spread the tumor.

Physical exam and case history

Including family history of eye cancer.

Eye examination under anesthesia

A detailed examination of both retinas with photographs, ultrasound and optical coherence tomography (OCT).

MRI

Of the eyes and brain to check whether the tumor has spread into the optic nerve or brain.

Genetic testing

A blood test for RB1 changes shows whether the retinoblastoma is heritable, which guides screening of siblings and future children.

Other tests

Bone marrow and spinal fluid tests are done only if spread outside the eye is suspected.

Treatment

The aims are to save the child's life, preserve the eye and keep as much vision as possible.

Treatment options include:

Surgery (enucleation) — removal of the eye when the tumor is very large or vision cannot be saved; an artificial eye is fitted later.
Laser therapy (transpupillary thermotherapy, TTT) — heat destroys small tumors.
Photocoagulation — laser light destroys the blood vessels feeding the tumor.
Cryotherapy — freezing treatment for small tumors at the front of the retina.
Chemotherapy — given through a vein, directly into the eye's artery (intra-arterial) or into the eye (intravitreal).
Radiation therapy — plaque brachytherapy or external radiation in selected cases.
High-dose chemotherapy with stem cell transplant — for retinoblastoma that has spread outside the eye.

Follow-up

Frequent eye examinations for several years, genetic counselling for the family, and long-term follow-up for children with heritable retinoblastoma, who have a higher risk of other cancers later in life.