Melanoma of the uveal tract (iris, ciliary body, and choroid), though rare, is the most common primary intraocular malignancy in adults. The mean age-adjusted incidence of uveal melanoma in the United States is approximately 4.3 new cases per million population. The age-adjusted incidence of this cancer has remained stable for the past 50 years.
Uveal melanoma is diagnosed mostly at older ages, with a progressively rising age-specific incidence rate that peaks near the age of 70. Host susceptibility factors associated with the development of this cancer include Caucasian race, light eye color, fair skin color, and the ability to tan.[1,2] In view of these susceptibility factors, numerous observational studies have attempted to explore the relationship between sunlight exposure and risk of uveal melanoma. To date, these studies have found only weak associations or yielded contradictory results. Similarly, there is no consistent evidence that occupational exposure to UV light or other agents is a risk factor for uveal melanoma.
Stage 0 melanoma is defined by the American Joint Committee on Cancer's TNM classification system:
Tis, N0, M0
Patients with stage 0 disease may be treated by excision with minimal, but microscopically free, margins.
Current Clinical Trials
Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage 0 melanoma. The list of clinical trials can be further narrowed by location, drug, intervention, and other criteria.
Uveal melanomas can arise in the anterior (iris) or the posterior (ciliary body or choroid) uveal tract. Iris melanomas have the best prognosis, whereas melanomas of the ciliary body have the worst. Most uveal tract melanomas originate in the choroid. The ciliary body is less commonly a site of origin, and the iris is the least common. The comparatively low incidence of iris melanomas has been attributed to the characteristic features of these tumors, i.e., they tend to be small, slow growing, and relatively dormant in comparison with their posterior counterparts. Iris melanomas rarely metastasize. Melanomas of the posterior uveal tract are cytologically more malignant, detected later, and metastasize more frequently than iris melanomas. The typical choroidal melanoma is a brown, elevated, dome-shaped subretinal mass. The degree of pigmentation ranges from dark brown to totally amelanotic.
Most uveal melanomas are initially completely asymptomatic. As the tumor enlarges, it may cause distortion of the pupil (iris melanoma), blurred vision (ciliary body melanoma), or markedly decreased visual acuity caused by secondary retinal detachment (choroidal melanoma). Serous detachment of the retina frequently complicates tumor growth. If extensive retinal detachment occurs, secondary angle-closure glaucoma occasionally develops. Clinically, several lesions simulate uveal melanoma, including metastatic carcinoma, posterior scleritis, and benign tumors, such as nevi and hemangiomas.
Careful examination by an experienced clinician remains the most important test to establish the presence of intraocular melanoma. Ancillary diagnostic testing, including fluorescein angiography and ultrasonography, can be extremely valuable in establishing and/or confirming the diagnosis.
A number of factors influence prognosis. The most important are cell type, tumor size, location of the anterior margin of the tumor, the degree of ciliary body involvement, and extraocular extension. Cell type, however, remains the most often used predictor of outcome. The selection of treatment depends on the site of origin (choroid, ciliary body, or iris), the size and location of the lesion, the age of the patient, and whether extraocular invasion, recurrence, or metastasis has occurred. Extraocular extension, recurrence, and metastasis are associated with an extremely poor prognosis, and long-term survival cannot be expected. The 5-year mortality rate caused by metastasis from ciliary body or choroidal melanoma is approximately 30%, compared with a rate of 2% to 3% for iris melanomas. In a group of patients with large tumors of the choroid or choroid and ciliary body, the concurrent presence of abnormalities in chromosomes 3 and 8 was also associated with a poor outcome.