Role of radiotherapy for primary orbital lymphoma

To define the role of radiation therapy of primary orbital lymphoma, a retrospective analysis was undertaken for 18 patients with primary orbital lymphoma who were treated with curative radiotherapy between 1984 and 1995. The histology was found to be low grade lymphoma in 11 patients, intermediate grade in 7. All patients were of Ann Arbor stage IE, but bilateral involvement of the orbit was observed in 3 patients (16.6%). Anatomical subsites involved were the retrobulbar, eyelid, and conjunctiva in eight, five, and four patients, respectively. The median radiation dose was 30 Gy ranging from 20 Gy to 50 Gy. Twelve of 18 patients received a radiation dose of 30 Gy or less. To properly protect the lens during irradiation, the contact lens blocks were used for nine patients with conjunctival and eyelid tumor or the hanging eye bar blocks were applied for eight patients with retrobulbar tumor. Chemotherapy was given for seven patients with intermediate-grade malignant lymphoma. Two patients had been treated by surgery before referral. The median follow-up period was 31 months ranging from 16 to 140 months. Overall complete response rate was 94.1%. All patients with low grade lymphomas and six of seven patients with intermediate grade lymphomas showed complete response to radiotherapy. Local failure was observed in three patients with intermediate grade lymphoma, who had destruction of the orbital wall at the time of initial diagnosis. By contrast, only one case showed distant relapse. Overall survival rate was 83.9%. All patients developed acute radiation conjunctivitis, but none had complications severe enough to interrupt radiotherapy. So far, there were no serious late complications. Low-dose (30 Gy) radiation treatment alone seems to be sufficient to control low grade primary orbital lymphoma. Carefully planned radiotherapy with appropriate lens shielding is an effective and safe treatment modality in the management of primary orbital lymphoma. For intermediate grade primary orbital lymphoma with extensive bony involvement, a planned combined modality with chemotherapy and radiotherapy should be considered.