OUTLINE: This is an open label, nonrandomized, multicenter study. Temozolomide is given by oral doses that are equally fractionated over 5 days and repeated every 4 weeks. Patients with brain metastases: Treatment is discontinued if there is progression of disease in both sites (brain and nonbrain) or if there is progression of disease of the brain lesion and stable disease of the other target lesions. Patients with progressive disease of the brain target lesions with contemporary evidence of response in the other target lesion can receive further temozolomide, in addition to nonchemotherapy medical treatment of the brain metastases (steroids, mannitol, etc.). Patients with progressive disease in the other target lesions with contemporary evidence of response of the brain target lesions can receive further temozolomide therapy, in addition to specific local radiotherapy of the nonbrain lesions. Patients without brain metastases: Treatment discontinues if there is clear cut progression occurring before the first disease evaluation (8 weeks after treatment start). For stable disease, the patient is treated for a minimum of 8 weeks and evaluated thereafter. Treatment, in most cases, is for a minimum of 2 cycles and may continue for a maximum of 6 cycles in the absence of disease progression, unacceptable toxicity, or patient refusal. All patients are followed every 6 weeks for survival.