Primary bilateral uveal melanoma: a population-based study and systematic review

Importance: Primary bilateral uveal melanoma (UM) is a rare and incompletely described entity. It is not known how these patients compare to those with unilateral UM. Background: We sought to comprehensively characterize and compare patients with primary bilateral and unilateral UM. Design: Retrospective, population-based and systematic review. Participants: Patients with bilateral (n = 52) and unilateral UM (n = 8915). Methods: We analysed cases of primary bilateral UM from three data sources: (i) the University Hospitals Cleveland Medical Center pathology database from 1996 to 2016 (n = 1); (ii) the Surveillance, Epidemiology and End-Results (SEER)-18 database from 1973 to 2013 (n = 5) and (iii) a systematic review of the English language literature (n = 46). Cases of unilateral UM were obtained from the SEER-18 database from 1973 to 2013 for comparison (n = 8915). Main Outcome Measures: Demographics, clinicopathological characteristics, treatments and survival. Results: There were no differences in sex, race, mean age at diagnosis, site of uveal involvement, metastases at diagnosis, or treatment among patients with bilateral as compared to unilateral UM. Additionally, there were no clinicopathological differences between the two UMs in each patient with bilateral disease. Overall survival did not differ between unilateral and bilateral UM patients, or between bilateral UM patients who presented with, or subsequently developed, bilateral disease. Conclusions and Relevance: Bilateral and unilateral UM patients share similar demographics, clinicopathological characteristics, treatments and prognoses. Moreover, the development of bilateral disease does not portend a poorer prognosis and patients should be treated similarly to those with unilateral disease.