Thirty-Year Experience of Radiotherapy for Primary Intraocular Lymphoma with and without Chemotherapy.

PURPOSE/OBJECTIVE(S): Primary intraocular lymphoma (PIOL) is a rare presentation of primary central nervous system lymphoma (PCNSL). We previously reported that ocular radiation therapy (RT) is an excellent option that can spare appropriate patients' upfront toxicity of whole brain radiotherapy (WBRT) and aggressive chemotherapy. A decade later, we expanded this series with almost double median follow up time.

MATERIALS/METHODS: We identified all patients seen at our institution from 1990-2022 treated for PCNSL or who received RT to the orbits. Detailed chart review was completed for cases with isolated ocular involvement at presentation (PIOL) who received RT to unilateral or bilateral orbits. Patients with disease on MRI brain or CSF cytology were excluded. Analysis included Kaplan-Meier method, log-rank-test, and Wilcoxon rank sum test. Overall survival (OS) was measured from diagnosis. Freedom-from-recurrence (FFR) measured time from RT start to first recurrence identified on imaging (parenchymal), slit-lamp exam (ocular), or biopsy.

RESULTS: A total of 75 patients were treated with RT to the orbits as part of management of PCNSL. 29 had PIOL with median follow up of 52 months from diagnosis. Of this subset, 22 (76%) received RT at our institution, median age at diagnosis was 65 (31-84) and 18 (62%) had bilateral disease. The majority were diagnosed by vitrectomy or vitreoretinal biopsy with B-cell lymphoma or unspecified lymphoma and 3 were clinically diagnosed. 17 patients received RT alone, 10 received RT after induction chemotherapy and 2 with induction and consolidation chemotherapy. Younger patients received chemotherapy (median age 60 vs 70, p = 0.03). RT dose ranged from 30 to 45 Gy, and 20 (69%) received 36 Gy, primarily with 1.8 Gy fractions. 22 (76%) received RT to bilateral orbits. 21 (72%) developed recurrence (Table 1), of which 6 (28.5%) recurred in a RT-treated eye and 11 (52.4%) isolated in the brain. 2 got salvage orbital RT and 4 got WBRT. Median OS was 5.4 years (95% CI 3.9, 7.6) and FFR was 8.4 months (95% CI 5.0, 25). There was no difference in OS (p = 0.4) or FFR (p = 0.3) between combined modality therapy versus RT alone.

CONCLUSION: In this updated experience, we demonstrate that RT alone remains an effective option for isolated PIOL, especially for those at risk of poor toleration of chemotherapy. Systemic therapy or WBRT can be utilized at recurrence, which primarily occurs in the brain. Future comparisons are needed to compare orbital RT to intravitreal therapies, and to investigate how these methods can complement each other to further improve management.