Risk Factors for Melanoma of the Eye Identified
You hear “melanoma” and think of skin cancer…but you may not know that 5% of melanomas (about 8,000 diagnosed new cases a year) occur in the eye. As with skin melanoma, uveal (eye) melanoma is deadly if not caught early. Unfortunately it’s not easy to spot the warning signs. To this end, researchers recently pinpointed several risk factors for uveal melanoma, including a few we can identify on our own and others that can be detected only by a qualified ophthalmologist during an eye exam.
UVEAL CANCER: A RARE BUT DEADLY DISEASE
Neil Shulman, MD, an associate professor of internal medicine at Emory University School of Medicine and coauthor of Your Body’s Red Light Warning Signals: Medical Tips That May Save Your Life, told me that the challenge with uveal melanoma is that there usually are no easily detectable symptoms in the early stages of the disease, unless the cancer forms in a location in the back of the eye, where it may cause noticeable visual disturbances. Fortunately, if the cancer is caught before it metastasizes, more than 90% of patients can be helped with radiation therapy, although some end up with impaired vision. If the melanoma has spread, prognosis is poor.
As with your skin, too much unprotected time in the sun can cause melanoma in your eyes, and the very same physical traits that raise your risk for skin melanoma also may put you at risk for uveal melanoma. In a meta-analysis to determine the strength of association, a group of researchers led by Ezekiel Weis, MD, at the Harvard School of Public Health in Boston, compared people with and without these risk factors. They learned that those with atypical moles are 2.8 times more likely to develop uveal melanoma…those with common moles had 1.7 times greater risk…and people with iris nevi (nonmalignant hyper-pigmentation spots on the iris) were 1.5 times more likely to develop uveal melanoma. Freckles were a weak but statistically significant predictor. The study appeared in the March issue of Ophthalmology.
SYMPTOMS TO KEEP AN EYE ON
Recently, Carol L. Shields, MD, ophthalmologist at the Wills Eye Institute at Thomas Jefferson University in Philadelphia, and her colleagues conducted a retrospective analysis of 2,514 eyes to identify factors that would help predict which choroidal nevi (precancerous moles inside the eye) will transform and grow into choroidal melanoma, the type that accounts for 95% of uveal melanomas. Using multivariate analysis, the researchers identified seven factors (traits) that predict the growth of choroidal nevi into melanoma, most of which can only be detected by an eye doctor using sophisticated equipment:
- Tumor thickness greater than 2 mm
- Subretinal fluid
- Symptoms (flashes, floaters, blurred vision or other visual field defects)
- Orange pigment
- Tumor margin near the optic disc
- Ultrasonographic hollowness
- Absence of a surrounding halo
A person whose nevus has one or two of these traits has a three times greater risk that it will turn into melanoma, compared with a nevus that has none. The risk increases to fivefold for nevi with three or four traits…to ninefold with five or six traits…and to 21-fold if all seven are present.
Visual impairment is the only trait a person would notice without an eye exam from a qualified ophthalmologist. If a melanoma is suspected, an ultrasound of the eye or a biopsy can confirm the diagnosis. Most cases of uveal melanoma can be treated with radiation—however, in certain cases, surgery of the affected portion of the eye may be required. Unfortunately, there usually is some permanent loss of vision.
SCREENING AND GOOD SUN SENSE
The average age at diagnosis is 55. If you are over 40, Dr. Shields recommends getting screened for uveal melanoma with an annual dilated retinal examination performed by a qualified eye-care professional. Those under 40 should have it every two years—and anyone and everyone who notices vision changes such as blurring, flashes or floaters, or the presence of a dark spot, a nevus or something that looks like a freckle in the eye itself should get it checked immediately.
Finally, limit your eyes’ exposure to strong sunlight by avoiding the sun in the middle of the day (when the sun is strongest) and by wearing UV-protection sunglasses when outdoors. “Good sense with clinical protection from chronic sun exposure is advised not just for the skin but for the eyes,” advises Dr. Shields.