Long-Term Follow-Up of Patients with Conjunctival Lymphoma after Individualized Lens-Sparing Electron Radiotherapy: Results from a Longitudinal Study

SIMPLE SUMMARY: This study investigates whether lens-sparing electron irradiation of low-grade, conjunctival lymphomas prevents cataract formation while ensuring high disease control rates. This study presents the data of 65 eyes of 56 patients with low-grade Ann Arbor stage I conjunctival lymphomas that were treated with either lens-sparing or non-lens-sparing electron irradiation. After a median follow-up of 65 months, the cumulative incidences of 5- and 10-year outfield progression were 10.4% and 13.4% while the cataract incidence was significantly lower in patients treated with a lens-shielding technique. The presented data underline the status of radiotherapy as first line therapy for low-grade conjunctival lymphomas. ABSTRACT: Irradiation with electrons is the primary treatment regime for localized conjunctival low-grade lymphomas. However, radiation-induced cataracts are a major cause of treatment-related morbidity. This study investigates whether lens-sparing electron irradiation produces sufficient disease control rates while preventing cataract formation. All consecutive patients with strictly conjunctival, low-grade Ann Arbor stage IE lymphoma treated with superficial electron irradiation between 1999 and 2021 at our department were reviewed. A total of 56 patients with 65 treated eyes were enrolled with a median follow-up of 65 months. The median dose was 30.96 Gy. A lens-spearing technique featuring a hanging rod blocking the central beam axis was used in 89.2% of all cases. Cumulative incidences of 5- and 10-year infield recurrences were 4.3% and 14.6%, incidences of 5- and 10-year outfield progression were 10.4% and 13.4%. We used patients with involvement of retroorbital structures treated with whole-orbit photon irradiation without lens protection—of which we reported in a previous study—as a control group. The cumulative cataract incidence for patients treated with electrons and lens protection was significantly lower (p = 0.005) when compared to patients irradiated without lens protection. Thus, electrons are an effective treatment option for conjunctival low-grade lymphomas. The presented lens-sparing technique effectively prevents cataract formation.