Metastatic conjunctival melanoma: a multicentre international study

BACKGROUND: To reveal clinical findings related to metastatic conjunctival melanoma. METHODS: 10 ophthalmic oncology centres (9 countries and 4 continents) shared data to create a large clinical case series. The main outcome measures were the incidence and cumulative risk of systemic metastasis, study mortality rates and Kaplan-Meier patient mortality after developing conjunctival melanoma metastasis. RESULTS: Of 288 patients, 29 developed metastasis. Five had metastasis at presentation, were American Joint Committee on Cancer (AJCC) cT3-category and exhibited tumour-surface ulceration. Four of five (80%) had melanotic tumours with plical and/or caruncular involvement and died within 1 year. One survived 21 months. In contrast, 24 developed metastases during follow-up (mean 4.6±3.2 years). Their primary tumours were cT1 (n=13/24, 54.1%), cT2 (n=6/24, 25%), cT3 (n=2/24, 8.3%) and 3 cTx (12.5%) at presentation. Death had occurred in 17 patients (n=17/24, 71%) by the end of the study. The cumulative risk of systemic metastasis after treatment was 0.4% (95% CI 0.6% to 2.9%) at 1 year, 8.6% (95% CI 5.1% to 14.3%) at 5 years and 22.3% (95% CI 14.5% to 33.5%) at 10 years. Each increase in AJCC cT category was associated with an 89% higher risk for metastasis (HR=1.89, p<0.001). Among all 29 patients who developed metastasis, those who presented with AJCC cT3 disease were at highest risk (p<0.001). Liver and lung (n=13 each) were the most reported metastatic sites. CONCLUSION: Metastatic conjunctival melanoma was found in 10% of conjunctival melanoma patients. Tumour-specific characteristics including AJCC cT3-category, conjunctival location and surface ulceration were associated with metastatic risk. Survival durations were shorter for those presenting with metastasis.