A melanoma is a malignant tumor that most often arises in the skin. Less commonly, it is found in the eye and other sites of the body. In the eye, melanoma arises from the pigmented cells (melanocytes) of the uvea (iris, ciliary body, or choroid). Melanoma carries the potential to spread from the eye to other parts of the body. Larger melanomas carry greater potential to spread than smaller tumors.
Melanoma affects approximately 2,000 to 2,500 people in the United States each year. It affects about six people per million population per year. Importantly, melanoma of the eye typically occurs in fair-skinned, blue or green-eyed men or women. Rarely is this tumor found in dark-skinned individuals. Hence, it is relatively rare in Asia and Africa.
The cause of melanoma is unknown. It has not been related to nutrition, smoking, drinking, or any environmental cause. Chronic sun exposure may play a role, but this is debatable. Melanoma almost always affects only one eye, and it is not hereditary. Therefore, family members are not at increased risk for this cancer. It can develop in an otherwise healthy patient.
The uveal melanoma is rarely diagnosed in children. In most situations, the median age at diagnosis is about 55 years. The rates of melanomas drop in both sexes after age 70 years. This is contrast of the majority of adult cancers in which the incident increases exponentially with age. In addition, uveal melanomas tend to be diagnosed nearly a decade earlier than most adult cancers.
Over the last several decades, a variety of alternative therapies to enucleation have been introduced for the treatment of intraocular melanomas in an effort to preserve the eye and whatever possible useful vision. The most commonly used methods today include radiation using charged particles (proton and helium ions), radioactive plaques such as Cobalt (Cobalt 60), iodine (iodine-125), and ruthenium (ruthenium-106), and local resection. Newer approaches include transpupillary thermal therapy in conjunction with or without simultaneous plaque radiotherapy, episcleral iridium water therapy, ultrasonically-induced hyperthermia as an adjunct to plaque therapy, palladium (palladium-103), Gamma-knife radiosurgery, and microwave thermotherapy combined with plaque. The vast majority of patients treated with plaque therapy retain full functioning in vision-related activities, particularly if the melanoma is outside the area centralis.