Radiation Therapy in the Management of Orbital Lymphoma

Abstract

To report our institution’s treatment techniques, disease outcomes, and complication rates after radiation therapy for the management of lymphoma involving the orbits. We retrospectively reviewed the medical records of 44 patients diagnosed with stage IAE (77%) or stage IIAE (23%) orbital lymphoma and curatively treated with radiation therapy between May 1969 and April 2013. The median follow-up was 4.9 years. Thirty-eight patients (86%) had low-grade lymphoma and 6 patients (14%) had high-grade lymphoma. Patients received treatment with one or more of the following beam energies: 250 kVP (34%), 60Co (36%), 2 MV (5%), 4 MV (16%), 6 MV (20%), or 8 MV (5%). Radiation was delivered with either wedge pair (61%), single anterior (34%), or anterior with bilateral wedges (5%) techniques. The median radiation dose was 25.5 Gy (range, 15 Gy – 47.5 Gy). Lens shielding was performed when possible. Cause-specific survival and freedom from distant relapse were calculated using the Kaplan-Meier method. The 5-year local control rate was 98%. Control of disease in the orbit was achieved in all but one patient who developed an out-of-field recurrence after irradiation of a lacrimal tumor and was salvaged successfully with further radiation therapy. The 5-year regional control rate was 91% (3 patients failed in the contralateral orbit and 1 patient failed in the ipsilateral parotid). Freedom from metastasis, cause-specific survival, and overall survival rates at 5 years were 76%, 89%, and 76%, respectively. Acute toxicity was minimal. Eight patients (18%) reported worsened vision following radiation therapy, and cataracts developed in eight patients. Cataracts developed in 6 of 28 patients treated without lens shielding (21%) and 2 of 16 patients (13%) treated with lens shielding. No patient developed significant late lacrimal toxicity. Radiation therapy is a safe and effective local treatment in the management of orbital lymphoma.