Local control and complications after radiation therapy for primary orbital lymphoma: a case for low-dose treatment.

Orbital involvement at the time of initial presentation is unusual in non-Hodgkin's lymphoma. In an effort to identify potential ways of improving the radiotherapeutic management of this disease, the records of 22 patients were reviewed retrospectively. All had biopsy-proven orbital non-Hodgkin's lymphoma, and the minimal, median, and maximal durations of follow-up in surviving patients were 4.8 years, 7.0 years, and 17.4 years, respectively. Permanent local control was achieved in 21 of the 22 patients (96%). Complications were scored according to a grading scheme in which grade 1 was the least significant complication and grade 4 was blindness as a result of radiation therapy. Of the 12 patients who received a radiation dose less than 35 Gy, 6 developed a grade 1 or grade 2 complication. Of the 10 patients treated with greater than or equal to 35 Gy, 6 experienced a complication, 1 of whom had a grade 4 complication resulting in blindness and another who developed a severe keratitis, which was scored as a grade 3 complication resulting in decreased visual acuity. At last follow-up, 10 patients were alive at 4.8 to 17.4 years after completion of radiation therapy, 4 had died of intercurrent disease at 3 months to 10.6 years, and 8 had died of disease at 3 months to 15.8 years. Actuarial survival for the entire group was 75% at 5 years and 48% at 10 years. Survival in patients with Stage I AE disease (lymphoma confined to orbit) at presentation was 87% at 5 years and 50% at 10 years, and survival in patients with Stage II A through Stage IV disease was 36% at 5 years and at 10 years. Primary orbital lymphoma is an indolent disease characterized by prolonged survival after radiation therapy. Excellent local control can be achieved with radiation doses of 20 Gy to 35 Gy. Higher doses may result in an increased risk of complications.