LAUSR

Background/Aims Lymphomas are the most frequent neoplasm of the orbit. However, the epidemiology of orbital lymphomas is not well reported. This study aimed to provide a population-based report on the epidemiology of orbital lymphomas and measure the trends in the incidence of orbital lymphoma cancer in South Korea. Methods Nationwide cancer incidence data from 1999 to 2016 were obtained from the Korea Central Cancer Registry. Age-standardised incidence rates and annual percent changes were calculated according to sex and histological types. The analysis according to the Surveillance, Epidemiology, and End Results summary stage classifications was performed from 2006 to 2016. Survival rates were estimated for cases diagnosed from 1999 to 2016. Results A total of 630 patients (median age: 54 years) with orbital lymphoma in the orbital soft tissue were included in this study. The age-standardised incidence rates increased from 0.03 to 0.08 per 100 000 individuals between 1999 and 2016, with an annual percent change of 6.61%. The most common histopathological type of orbital lymphoma was extra marginal zone B cell lymphoma, accounting for 82.2% of all orbital lymphomas during 1999–2016, followed by diffuse large B cell lymphoma (9.2%). Five-year, 10-year and 15-year overall survival (OS) of orbital lymphoma was 90.8%, 83.8% and 75.8%, respectively. OS showed a significant decrease as age increased and no significant differences between men and women. Conclusion The incidence rate of orbital lymphoma is very low in South Korea. However, the incidence rate has increased over the past years. Orbital lymphomas have a worse prognosis as age increases.