Metastasis of uveal melanoma millimeter-by-millimeter in 8033 consecutive eyes.

Objective: To determine the rate of metastasis of uveal melanoma on the basis of tumor thickness in millimeters.

Methods: Retrospective medical record review.

Results: The mean (median) patient age was 58 (59) years. A total of 8033 eyes were examined. Of the 285 eyes with iris melanoma, the mean tumor thickness was 2.7 mm and metastasis occurred in 0.5%, 4%, and 7% at 3, 5, and 10 years, respectively. Of the 492 eyes with ciliary body melanoma, the mean tumor thickness was 6.6 mm and metastasis occurred in 12%, 19%, and 33% at 3, 5, and 10 years, respectively. Of the 7256 eyes with choroidal melanoma, the mean tumor thickness was 5.5 mm and metastasis occurred in 8%, 15%, and 25% at 3, 5, and 10 years, respectively. For all uveal melanoma, metastasis at 5, 10, and 20 years was 6%, 12%, and 20% for small melanoma (0-3.0 mm thickness), 14%, 26%, and 37% for medium melanoma (3.1-8.0 mm), and 35%, 49%, and 67% for large melanoma (>8.0 mm). More specifically, metastasis per millimeter increment at 10 years was 6% (0-1.0 mm thickness), 12% (1.1-2.0 mm), 12% (2.1-3.0 mm), 16% (3.1-4.0 mm), 27% (4.1-5.0 mm), 28% (5.1-6.0 mm), 29% (6.1-7.0 mm), 41% (7.1-8.0 mm), 50% (8.1-9.0 mm), 44% (9.1-10.0 mm), and 51% (>10.0 mm). Clinical factors predictive of metastasis by multivariate analysis included increasing patient age, ciliary body location, increasing tumor diameter, increasing tumor thickness, having a brown tumor, and the presence of subretinal fluid, intraocular hemorrhage, or extraocular extension.

Conclusion: Increasing millimeter thickness of uveal melanoma is associated with increasing risk for metastasis.