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. All data relevant to the study are included in the article or uploaded as online supplemental information.