RADIATION-THERAPY FOR PRIMARY ORBITAL LYMPHOMA

Purpose: The influence of tumor size, grade, thoroughness of staging w orkup, and radiation dose on disease control, radiation-related compli cations, and incidence of systemic progression of primary orbital lymp homa is analyzed. Methods and Materials: Twenty patients with Stage I primary orbital lymphoma were treated from August 1976 through August 1991 at Mallinckrodt Institute of Radiology, Staging workups included physical examination, chest x-ray, complete blood count (CBC), liver f unction test, and computerized tomography (CT) scan of the orbit, abdo men, and pelvis. Nineteen patients had bone marrow biopsy. The histolo gical types based on the National Cancer Institute working formulation were 9 low-grade and 11 intermediate-grade, including five lymphocyti c lymphomas of intermediate differentiation. The extension of disease and the volume of tumor were evaluated by CT scan of the orbit. The mo st commonly used radiation therapy technique was single anterior direc t field with 4 MV or 6 MV photons. Lens was shielded or not treated in eight patients. Dose ranged from 20 to 43.2 Gy. Thirteen of 20 patien ts received 30 Gy. Minimum follow-up was 24 months (median, 4 years). Results: Local control was achieved in all 20 patients. One patient wi th lymphocytic lymphoma with intermediate differentiation developed di sseminated disease. Actuarial disease-free survival (DFS) was 100% and 90% at 2 and 5 years, respectively. No retinopathy was observed. Cata racts were noted in seven patients at 1 to 10 years following irradiat ion (median, 2 years). Three patients developed lacrimal function diso rder; however, no corneal ulceration occured. Conclusions: Thirty Gy i n 15 fractions appears to be a sufficient dose for local control with acceptable morbidity, especially for low-grade, as well as certain typ es of intermediate-grade lymphomas, such as diffuse small cleaved cell and lymphocytic lymphoma of intermediate differentiation. Systemic di ssemination is minimal, provided local control is achieved and initial staging workups are adequate.