RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Gadolinium texaphyrin may increase the effectiveness of radiation therapy by making tumor cells more sensitive to radiation. It is not yet known whether giving gadolinium texaphyrin with radiation therapy is more effective than radiation therapy alone in treating brain metastases.

PURPOSE: Randomized phase III trial to compare the effectiveness of radiation therapy with or without gadolinium texaphyrin in treating patients who have brain metastases.

OBJECTIVES: I. Determine the safety of gadolinium texaphyrin administered prior to whole brain radiotherapy in patients with brain metastases. II. Compare the efficacy and toxicity of whole brain radiotherapy with or without gadolinium texaphyrin in these patients. III. Assess the quality of life of these patients.

OUTLINE: This is a randomized, two stage, multicenter study. Patients are stratified according to RTOG recursive partitioning analysis class (RPA class 1 vs class 2) and tumor type (breast vs lung vs other). Stage 1 (lead-in): All patients receive gadolinium texaphyrin IV over 5-10 minutes on the 10 days that they receive radiotherapy. Approximately 2-5 hours later, patients undergo whole brain radiotherapy. Stage 2 (randomization): Patients are randomized to one of two treatment arms. Patients in arm I undergo whole brain radiotherapy for 10 days. Patients in arm II receive gadolinium texaphyrin and radiotherapy as in stage 1. Quality of life is assessed on days 10 and 28, then monthly for 5 months, and then every 3 months thereafter. Patients are followed at day 28, then monthly for 5 months, and then every 3 months until death.

PROJECTED ACCRUAL: The lead-in phase will accrue at least 25-30 patients and the randomization phase will accrue 400 patients (200/arm) over a 12 month period.

DISEASE CHARACTERISTICS: Histologically proven solid tumor with parenchymal brain metastasis Solitary metastasis eligible only if refused surgery or surgical resection deemed inappropriate No leptomeningeal metastases or subarachnoid spread of tumor No small cell lung cancer, germ cell tumors, lymphoma, or leukemia No liver metastases, unless from breast cancer No more than 1 site of extracranial metastases (multiple bone or lung metastases count as one site), unless from breast cancer Hormone receptor status: Not specified

PATIENT CHARACTERISTICS: Age: 18 and over Menopausal status: Not specified Performance status: Karnofsky 70-100% Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 50,000/mm3 Hepatic: Bilirubin no greater than 2 times upper limit of normal (ULN) AST and ALT no greater than 2 times ULN Renal: Creatinine no greater than 2.0 mg/mL Other: No history of porphyria No history of G6PD deficiency HIV negative No other major medical illnesses No major psychiatric impairment Not pregnant or nursing Negative pregnancy test

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No chemotherapy during and for 2 weeks after gadolinium texaphyrin therapy Endocrine therapy: Concurrent hormonal therapy allowed Radiotherapy: No prior cranial radiation, including prior stereotactic radiosurgery No plan for radiosurgery or radiation boost following whole brain radiotherapy Concurrent radiotherapy allowed to other sites, except kidneys and liver Surgery: No prior subtotal or total resection of brain metastases (except biopsies)