An International Lymphoma Radiation Oncology Group Study of Radiation Therapy for Bilateral Indolent Orbital Adnexal Lymphomas

Abstract

Purpose: Radiation therapy (RT) is curative for the majority of patients with primary indolent orbital adnexal lymphoma (IOAL). Some reports suggest inferior outcomes for bilateral IOAL, leading to uncertainty regarding optimal management for this presentation. This multicenter, retrospective study evaluated long-term outcomes of bilateral IOAL patients treated with RT alone. Methods and materials: One hundred and eighty-four patients with synchronous (defined as <= 90 days between orbit diagnoses), or metachronous bilateral IOAL, and no prior lymphoma history, received RT to both orbits. Overall (OS), failure-free survival (FFS), freedom from local failure (FFLF), freedom from distant failure (FFDF), and toxicity were evaluated. The study met local institutional review board requirements. Results: A total of 184 patients were treated for IOAL from 16 centers. The median age at first orbit diagnosis was 51 years (15-91 years) with 170 (92%) of patients having marginal zone lymphoma. Disease location included the conjunctiva in 265 (72%) of orbits. The RT dose (per orbit) was 4 Gy for 40 (11%), 20 to 26 Gy for 217 (59%), 27 to 30.6 Gy for 87 (24%), and >30.6 Gy for 24 (6.5%). Radiation therapy volume was whole orbit for 162 (44%), conjunctiva only for 177 (48%), and other partial orbit for 29 (8%). The median follow-up was 5.7 years. Ten-year OS and FFS were 99% (95% CI, 95-100) and 72% (95% CI, 62-79), respectively. Ten-year FFLF and FFDF were 87% (95% CI, 80-92) and 81% (95% CI, 72-88), respectively. Ten-year FFS was 85% (95% CI, 75-91) and 50% (95% CI, 32-65) for patients with conjunctival-only disease versus any nonconjunctival disease, respectively. Late toxicities included dry eye in 42% of patients (grade 1 in 86%) and cataract in 27%. Conclusions: In this large, multicenter experience, patients with bilateral IOAL treated with RT alone had outcomes comparable with historical series of unilateral disease. These results support the treatment of bilateral IOAL as a localized process with curative intent RT.