Melanoma of the uveal tract, the part of the eye that lies between the sclera (the “white” of the eye) and the retina, is the most common intraocular tumor, and the main primary eye tumor that may be fatal. Fewer than 2,000 new cases are diagnosed each year in the United States. Arising from melanocytes, they can develop in any part of the uveal tract, which includes the iris (at the front of the eye), ciliary body, and the choroid (at the back of eye). Melanomas of the iris are rare (approximately 5% of cases). Choroidal tumors are most common, though tumors confined to the ciliary body are more often fatal.
An ocular oncologist performs a complete eye examination, including an evaluation of the back of your eye after dilating the pupils, to determine if a lesion in your eye is uveal melanoma. To assess the tumor, photographs and an ultrasound of the eye will also be taken. Most cancers involve biopsy of the tumor, but uveal melanoma does not. Instead, diagnosis is based on several clinical characteristics. If a small lesion is present and the diagnosis is not certain, close follow-up is indicated.
The most widely accepted management for malignant melanomas of the choroid and ciliary body is radiotherapy (RT). Two available forms of RT include: brachytherapy using radioactive plaques that are sutured to the sclera, and external beam radiation therapy (EBRT), which uses heavy, charged particles, such as protons. Surgery to remove the eye, or enucleation, is usually reserved for patients with very large melanomas (occupying greater than 30% of the eye).
The type of radiotherapy used at Mass. Eye and Ear is proton irradiation, a very precise form of radiation therapy. The radiation beam can be very closely controlled and can be directed with accuracies within 1 mm. It is particularly useful for the treatment of tumors close to the optic nerve head and the macula (area of central vision), and in treating larger tumors. For these tumors, the chances of maintaining useful vision are higher than with plaque RT.
Before receiving radiation treatment, most patients with uveal melanomas have surgery to localize the tumor. Four markers, called tantalum rings, are sutured around the edges of the tumor so that the treating oncologist can accurately place the proton beam when irradiating the tumor. During treatment, the patient is seated, the eyelids are retracted to reduce radiation exposure to the eyelid, and the head is immobilized with the aid of a head holder. The patient is asked to fixate for approximately two minutes while the tumor is irradiated. The entire radiation session requires 15 to 20 minutes to complete. The treatment regimen consists of five treatments of 1,400 rads (the unit for measuring all types of radiation) for a total dose of 7,000 rads.
Patients are given dilating drops and an antibiotic ointment to use during, and a few days after, radiation treatment.
Follow-Up After Treatment
Regular follow-up after treatment is important to monitor tumor recurrence or spread of the tumor to other parts of the body (metastasis). Follow-up examinations typically include clinical examination of the eye, photographs, and ultrasound to evaluate the tumor for regrowth, and blood liver enzyme tests to check for spread of the tumor to the liver. If necessary, liver imaging studies (CAT scan, MRI) may be performed. Ophthalmological examinations are performed six weeks, six months, and 12 months after treatment, biannually thereafter up to five years after treatment, and then annually, to monitor the status of both tumor and patient.
If you have been diagnosed with a uveal melanoma or another eye tumor and wish to be evaluated for this condition, please call Dr. Evangelos Gragoudas at 617-573-3735 or Dr. Ivana Kim at 617-573-3367. Drs. Gragoudas and Kim are ocular oncologists specializing in treating intraocular tumors.