Melanoma is a type of skin cancer that originates from cells called “melanocytes”. These are the pigment-forming cells that produce melanin, which is more commonly associated with skin color. These cells however, are not only found in the skin, but also in other parts of the body such as the eye.
As its name suggests, Ocular Melanoma is a certain type of skin cancer that grows on one’s eye. Most commonly, this cancerous growth develops in the choroid layer, which contains these pigments to block the light reflecting around the inside of the eye. It is located between the sclera (a white fibrous tissue on the outside of the eye) and retina (the innermost layer of the eye). When the tumour forms here, vision starts to blur, and pressure builds on the eyeball.
The outlook for local cure depends strongly on the size and growth rate of the tumour. At TRIUMF, the treatment offered is radiotherapy. Specifically, proton therapy has an average success rate of 95% for tumour control, and the average five-year survival rate is 80%, which is at par with enucleation or surgical removal of the eye. The advantage with radiotherapy, however, is that in most cases, the eye can be saved and vision may be restored.
This type of tumour is very rare. The disease incidence in Europe and the United States is approximately 7.5 cases annually per million population, and the exact cause is unknown. The Eye Care Centre sees about 40 cases a year, but only 10 of those will come to TRIUMF for Proton Eye Cancer Therapy.