Retinoblastoma

Retinoblastoma is a rare cancer of the retina — the light-sensitive tissue at the back of the eye. It occurs almost entirely in young children, usually before age 5. Although rare, India has one of the largest absolute numbers of retinoblastoma cases in the world because of our large child population. Early detection saves sight, and often saves lives.

Types

• Hereditary retinoblastoma — caused by an inherited mutation in the RB1 gene. Usually affects both eyes and is often diagnosed in infancy. Children with hereditary retinoblastoma are at higher risk of other cancers later in life.
• Non-hereditary (sporadic) retinoblastoma — a random mutation; usually affects one eye and tends to be diagnosed a bit later.

Signs — what to look for

The most common early sign is a white reflex in the pupil instead of the normal red or black — particularly visible in flash photographs. This is called leukocoria. Other signs:

• A squint (strabismus) in a young child
• Redness or swelling of the eye (not from injury)
• Poor vision in one eye
• A change in the colour of the iris
• Pain or discomfort

Any child — particularly under 5 — with a white pupil in photographs, a new squint, or an unusually red eye should be seen by a paediatrician or ophthalmologist promptly. Don't wait.

Diagnosis

• Dilated eye examination by a paediatric ophthalmologist, often under anaesthesia in a young child
• Ultrasound of the eye
• MRI — to assess local spread and rule out involvement of the optic nerve or brain
• Genetic testing — for RB1 mutation, important for family planning and screening siblings

Treatment

Treatment has advanced hugely over the past two decades. The goals, in order, are: (1) save the child's life, (2) save the eye, (3) save vision. Options are individualised based on tumour size, location, whether one or both eyes are affected, and whether it has spread:

• Chemotherapy — intravenous, intra-arterial (directly into the eye's artery), or intravitreal (into the eye)
• Focal therapies — laser, cryotherapy, or plaque brachytherapy for small tumours
• Radiation therapy — external beam is now used less often (second-cancer risk in hereditary cases)
• Enucleation (removal of the eye) — for large tumours when other options cannot save vision; often life-saving
• Long-term follow-up — for recurrence, second eye involvement, and second cancers in hereditary cases

If a child is diagnosed, genetic counselling for the family is important — siblings of children with hereditary retinoblastoma should be screened.