Backgrounds/aims To date, this is the largest cohort study on extranodal marginal zone B-cell lymphoma (EMZL) of the ocular adnexa (OA). The aim of the study was to characterise the clinical features of OA-EMZL.

Methods A retrospective multicentre study involving seven international eye cancer centres. Data were collected from 1 January 1980 through 31 December 2017. A total of 689 patients with OA-EMZL were included.

Results The median follow-up time was 42 months. The median age was 62 years (range, 8–100 years), and 55 % (378/689 patients) of patients were women. The majority of patients (82%, 558/680 patients) were diagnosed with primary OA-EMZL with Ann Arbor stage IE (90%, 485/541 patients) and American Joint Committee on Cancer stage T2 (61%, 340/557 patients) at the time of diagnosis. The orbit (66%, 452/689 patients) and the conjunctiva (37%, 255/689 patients) were the most frequently involved anatomical structures. The 5-year, 10-year and 20-year disease-specific survival (DSS) were 96%, 91% and 90%, respectively. Stage IE patients treated with external beam radiation therapy (EBRT) as monotherapy (10-year DSS, 95%) were found to have a better DSS than stage IE patients treated with chemotherapy (10-year DSS, 86%). Stage IIIE/IVE patients treated with chemotherapy and rituximab had a better DSS (10-year DSS, 96%) than stage IIIE/IVE patients treated with chemotherapy without rituximab (10-year DSS, 63%).

Conclusions and relevance EMZL is a slow-growing tumour with an excellent long-term survival. Low-dose EBRT as monotherapy should be considered in localised OA-EMZL. Rituximab-based chemotherapy should be chosen in those patients with disseminated disease.