Chromosome 3 and 8q Aberrations in Uveal Melanoma Show Greater Impact on Survival in Patients with Light Iris versus Dark Iris Color

Abstract

Purpose: Individuals with gray, blue, or green eyes have a higher chance of developing uveal melanoma (UM) than those with brown eyes. We wondered whether iris pigmentation might be related not only to predisposition to UM but also to its behavior; therefore, we compared the clinical, histopathologic, and genetic characteristics of UM between eyes with different colors.

Design: We determined iris color in a large cohort of patients enucleated for UM. Clinical and histopathologic tumor characteristics, chromosome status, and survival were compared among 3 groups on the basis of iris color.

Participants: A total of 412 patients with choroidal/ciliary body UM, who had undergone primary enucleation at the Leiden University Medical Center, Leiden, The Netherlands, between 1993 and 2019, were divided into 3 groups based on iris color: gray/blue, green/hazel, and brown. The validation cohort included 934 patients with choroidal/ciliary body UM treated at Wills Eye Hospital (WEH).

Methods: Comparison of clinical, histopathologic, and genetic characteristics of UM in patients with different iris colors.

Main outcome measures: Melanoma-related survival in UM patients, divided over 3 iris color groups, in relation to the tumor's chromosome 3 and 8q status.

Results: Moderate and heavy tumor pigmentations were especially seen in eyes with a brown iris (P < 0.001). Survival did not differ between patients with different iris colors (P = 0.27); however, in patients with a light iris, copy number changes in chromosome 3 and 8q had a greater influence on survival than in patients with a dark iris. Likewise, chromosome 3 and chromosome 8q status affected survival more among patients with lightly pigmented tumors than in patients with heavily pigmented tumors. The WEH cohort similarly showed a greater influence of chromosome aberrations in light-eyed individuals.

Conclusions: Although iris color by itself did not relate to UM-related survival, chromosome 3 and 8q aberrations had a larger influence on survival in patients with a light iris than those with a brown iris. This suggests a synergistic effect of iris pigmentation and chromosome status in the regulation of oncogenic behavior of UM. Iris color should be taken into consideration when calculating a patient's risk for developing metastases.

Keywords: Color; Eye disease; Inflammation; Iris color; Oncology; Prognosis; Uveal Melanoma.