Radiation Therapy and High-Dose Corticosteroids in Treating Older Patients With Primary CNS Non-Hodgkin's Lymphoma

OBJECTIVES: * Assess the effectiveness of high-dose dexamethasone after whole-brain radiotherapy in maintaining response and preventing recurrence in elderly patients with primary central nervous system non-Hodgkin's lymphoma. * Assess the toxic effects of this regimen in these patients. * Assess the survival rate of patients after this regimen. * Identify the anatomic rates of recurrence and frequency of systemic involvement in patients treated with this regimen. * Identify the factors that appear to be associated with outcome in patients treated with this regimen. OUTLINE: Patients undergo whole-brain radiotherapy (WBRT) daily 5 days a week for 4.5 weeks. Beginning 30 days after WBRT is completed, patients receive high-dose dexamethasone IV on days 1-5 during course 1 and on day 1 only during all subsequent courses. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients are followed at 1 month after radiotherapy, every 3 months for 2 years, every 6 months for 3 years, and then annually thereafter. PROJECTED ACCRUAL: A total of 28 patients will be accrued for this study within 6 years.