P1127: WATCHFUL WAITING IS AN ACCEPTABLE TREATMENT OPTION FOR PRIMARY OCULAR ADNEXAL MUCOSA-ASSOCIATED LYMPHOID TISSUE LYMPHOMA: A RETROSPECTIVE STUDY

Abstract

Background: Primary ocular adnexal mucosa-associated lymphoid tissue (MALT) lymphoma (POAML) is the most frequent subtype of ocular adnexal lymphomas. Radiotherapy (RT) is the standard of care for localized POAML, despite several complications, such as cataracts, retinitis, dry eye, and optic neuropathy. Watchful waiting (WW) is expected to be a therapeutic option for POAML, however, its efficacy for POAML remains to be verified. Aims: The aim of the study was to clarify the validity of WW for POAML. Methods: We retrospectively analyzed the background, disease status, treatments, and clinical outcomes of patients histologically diagnosed with POAML between 2008 and 2019 at seven institutes belonging to the Kyoto Clinical Hematology Study Group. The primary ocular adnexal disease sites were defined as involvement of the conjunctiva, orbit, eyelid, or lacrimal gland. Bilateral ocular adnexal lymphoma without other lymphomatous involvement was defined as stage IE disease. Results: One hundred and three patients were diagnosed with POAML, of which 11 were excluded from analysis because of lost follow-up, 11 due to missing data, and 6 due to short follow-up within 1 year. As a result, 75 patients were analyzed in this study. The median age was 68 years, and 41 patients (54.7%) were females. The most common involved site was the conjunctiva (42.7%), followed by the orbit (36.0%), lacrimal gland (12.0%), and eyelid (8.0%). Sixty-nine patients (92.0%) presented with stage IE disease, and 61 patients (81.3%) presented with a unilateral ocular region. According to the International Prognostic Index, most patients (92.0%) were classified as low risk. The tumor was completely resected at diagnosis in 17 patients (22.7%), while a residual tumor existed after biopsy in 58 patients (77.0%). WW was the most frequent first-line modality, selected for 29 patients (38.7%), including 14 patients with complete tumor resection at diagnosis. Twenty-four patients (32.0%) were treated with RT and 19 (25.3%) with rituximab monotherapy (R). In the RT group, most patients had a residual tumor after the biopsy, and the orbit was the most frequent site of lymphoma, which caused treatment-emergent symptoms that potentially impair visual function. Complete response rates were 79.2% and 42.1% in the RT and R groups, respectively. With a median follow-up of 48.8 months, there were no significant differences in the time to start of new treatment between WW and RT groups (median: both not reached [NR], p = 0.187) and between WW and R groups (median: NR vs. 69.0 months, p = 0.554). At 60 months follow-up, the estimated proportions of POAML patients not requiring new treatment were 69.4%, 85.2%, and 53.8% in the WW, RT, and R groups, respectively. All patients enrolled in this study were alive at the time of analysis. In the WW group, 9 patients (31.0%) showed disease progression, seven of whom received treatments with a median time to next treatment of 15.6 months, but the remaining two patients continued WW even after disease progression because of no subjective symptoms. In the RT group, 16 patients (66.7%) developed adverse events, most of which were mild, while grade 3 cataracts occurred in five patients. We compared the clinical characteristics to identify predictive factors for disease progression in the WW group, however, all factors analyzed were not significantly associated with disease progression. Summary/Conclusion: WW may be an acceptable treatment option for POAML, especially in asymptomatic patients.