Retinoblastoma

This is the most common intraocular cancer in children, with an estimated 400 – 500 cases in the U.S each year. It is extremely rare in adults.

There are two types of retinoblastoma; one is hereditary and affects both eyes (occurs in 10 percent of cases) and the other type is non-hereditary and affects only one eye. Although the cancer is genetically determined, only 6 percent of newly diagnosed RB patients are found to have a positive family history of the disease. In all cases, genetic counselling is important for children with a germ-line mutation.

Retinoblastoma is graded A through E, with A being the least advanced form of the disease. Because of recent advances, group A can now be treated with a laser or cryotherapy. Groups B through D traditionally received systemic chemotherapy, which can affect other parts of the body. Class D had almost a 50 percent failure rate with systemic chemotherapy. Class E patients needed to have the affected eye removed.

Tests

Retinal Examination – Using an ophthalmoscope, the doctor will exam the retina while the eyes are dilated.

Optical Coherence Tomography (OCT) – This imaging test creates a cross-sectional, three-dimensional (3-D) view of the inside of the eyes.

Ultrasound – This safe, painless test uses high-frequency sound waves to produce detailed images of the inside of the eyes and eye socket.

Fluorescein Angiography – Using this method, your doctor can see changes in the structure or function of the retinal blood vessels. To perform the test, the doctor injects dye into a vein in the arm or hand, then photographs the retina as the dye outlines the blood vessels.

Electroretinogram – An electroretinography (ERG) test or electroretinogram, measures the electrical response of the light-sensitive cells in your eyes.

Bone scan – Bone scans help show if retinoblastoma has spread into other bones or the skull.

Lumbar puncture (spinal tap) – If retinoblastomas grow on the optic nerve, and if there is a suspected cancer on the brain’s surface, this test can find cancer cells. We analyse a small sample of cerebrospinal fluid (which surrounds the brain and spinal cord) under a powerful microscope.

Bone marrow aspiration and biopsy – These tests are typically only used when we suspect the retinoblastoma is growing outside the eye and that cancer is spreading through the blood and into the bone marrow.

Treatments

Intra-arterial Chemotherapy – With localized intra-arterial chemotherapy, young patients with C-E graded retinoblastomas are spared the long-term effects of systemic chemotherapy. Also, the need to remove the eye drops by 50 percent.

With this chemotherapy, a thin catheter is threaded into the femoral artery in the groin, up into the carotid artery in the neck and into the ophthalmic artery. The chemotherapy is then delivered into the ophthalmic artery. Some patients need two or three treatments three weeks apart. Only about five percent of patients fail to respond to this treatment. When they do, it is usually because of cancer cell spreading into the vitreous, the gel inside the eye. An ophthalmic oncologist can directly inject chemotherapy into the eye to address those cells, without the chemotherapy affecting other parts of the body.

Cryotherapy – This therapy uses cold to freeze and destroy cancer cells and can also be used with retinoblastoma.