Iris Melanoma Outcomes Based on the American Joint Committee on Cancer Classification (Eighth Edition) in 432 Patients.

PURPOSE

The American Joint Committee on Cancer (AJCC) classification was updated to the eighth edition in January 2017, providing staging for iris melanoma. This study evaluated outcomes of iris melanoma per the AJCC classification, eighth edition.

DESIGN

Retrospective case series.

PARTICIPANTS

Four hundred thirty-two patients with iris melanoma.

METHODS

Management including tumor resection, plaque radiotherapy, or enucleation.

MAIN OUTCOME MEASURES

Local tumor recurrence, melanoma-related systemic metastasis, and melanoma-related death.

RESULTS

Of 432 patients with iris melanoma, AJCC classification was category T1 (n = 324 [75%]), T2 (n = 83 [19%]), T3 (n = 2 [<1%]), and T4 (n = 23 [5%]). There was no difference in age, race, gender, eye, or iris color among T categories. Overall, Kaplan-Meier analysis of outcomes (at 5 and 10 years) revealed visual acuity reduction by 3 lines or more (42% and 54%, respectively), secondary glaucoma (29% and 33%, respectively), local recurrence (8% and 17%, respectively), secondary enucleation (12% and 19%, respectively), lymph node metastasis (1% and 1%, respectively), melanoma-related systemic metastasis (5% and 10%, respectively), and melanoma-related death (3% and 4%, respectively). Compared with T1 category, the hazard ratio (HR) for local recurrence in nonenucleated eyes was 1.31 for T2, not evaluable (NE) for T3 (because of small cohort), and 6.61 for T4; the HR for metastasis was 3.41 for T2, NE for T3 (because of small cohort), and 25.6 for T4; the HR for death was 7.51 for T2, NE for T3 (because of small cohort), and 26.5 for T4; and the odds ratio for enucleation was 1.23 for T2, 3.63 for T3, and 4.72 for T4. Features predictive of melanoma-related metastasis (multivariate analysis) included secondary glaucoma (P < 0.001; HR, 4.51), T2 category (vs. T1; P = 0.01; HR, 4.09), and T4 category (vs. T1; P < 0.001; HR, 30.8). Features predictive of melanoma-related death (multivariate analysis) included older age (P = 0.008; HR, 2.16 per 10-year increase), T2 category (vs. T1; P = 0.005; HR, 8.07), and T4 category (vs. T1; P < 0.001; HR, 20.3).

CONCLUSIONS

The AJCC eighth edition classification provides prognostic stratification of iris melanoma. By multivariate analysis, the ratio for melanoma-related metastasis was 4 times greater in category T2 and 31 times greater in T4 compared with T1. The ratio for melanoma-related death was 8 times greater in category T2 and 20 times greater in T4 compared with T1. The cohort size for T3 was too small to provide useful information.