The correlation between uveal melanoma and iris nevus

Abstract Purpose To investigate the impact of iris nevus on the incidence and prognosis of uveal melanoma (UM). Methods A retrospective cohort study was conducted involving 1128 UM cases and 4356 healthy controls. Participants were categorized based on iris nevus presence and grade: grade 0 (no iris nevus), grade 1 (single iris nevus), grade 2 (multiple iris nevi), and grade 3 (partial or complete darkening of the iris). Propensity matching score method was employed to control for age and sex differences, while the χ 2 test was used to compare the existence rate and grade of iris nevus between groups. Univariate ANOVA evaluated differences among various iris nevus grades, the Kaplan–Meier method analyzed the prognosis of patients with different iris nevus grades, and multivariate Cox proportional risk regression analysis was conducted to evaluate the relationship between clinical data and prognosis. Results A total of 5484 subjects were analyzed. UM patients exhibited a higher prevalence and grade of iris nevus (all P < 0.001) after propensity matching. Patients with iris nevus in the affected eye did not show a worse prognosis ( P = 0.414). However, those with partial or complete iris darkening or multiple nevi had a poorer prognosis compared to those with a single or no iris nevus (all P < 0.05). Iris nevus presence and grade in the healthy eye had no prognostic impact ( P = 0.726 and P = 0.825, respectively). The multivariate COX proportional risk model showed that tumor diameter ( P < 0.001), age ( P = 0.020), and grade of iris nevus in the affected eye ( P = 0.009) were independent risk factors for a worse prognosis. LSD analysis revealed that patients with partial or complete darkening of the iris had larger tumor diameters than those without iris nevus ( P = 0.013), single nevus ( P = 0.015), and multiple nevus ( P = 0.023). Discussion Our findings indicate a higher proportion and grade of iris nevus in UM patients compared to controls, and a worse prognosis for UM patients with higher-grade iris nevi in the affected eye.