 RATIONALE: Steroid therapy, such as dexamethasone, may reduce swelling, pain, and other symptoms of inflammation and may be effective in treating some of the problems caused by cancer and cancer treatment. Supportive care improves the quality of life of patients with a serious or life-threatening disease, and prevents or treats symptoms of cancer, side effects of treatment, and other problems related to cancer or its treatment. Radiation therapy uses high-energy x-rays to kill tumor cells. It is not yet known whether dexamethasone given together with supportive care is more effective with or without whole-brain radiation therapy in treating patients with brain metastases. 