Temozolomide With or Without Radiation Therapy to the Brain in Treating Patients With Stage IV Melanoma That Is Metastatic to the Brain

DISEASE CHARACTERISTICS: * Histologically confirmed unresectable metastatic melanoma * Must have asymptomatic brain metastasis that is not amenable to surgery or stereotactic radiosurgery (gamma knife, Linac) * Must have concurrent visceral/soft tissue metastases * At least 1 site of measurable disease (not necessarily the brain metastasis) * Documented evidence of disease progression defined by 1 of the following conditions: * More than 25% increase in the size of at least 1 measurable lesion * Appearance of a new lesion * A significant increase in the size of nonmeasurable disease * No neurological symptoms, including signs of elevated intracranial pressure PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * ECOG 0-2 Life expectancy: * Not specified Hematopoietic: * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Hemoglobin at least 10 g/dL Hepatic: * Bilirubin less than 1.5 times upper limit of normal (ULN) * SGOT or SGPT less than 3 times ULN * Alkaline phosphatase less than 3 times ULN Renal: * Urea less than 1.5 times ULN * Creatinine less than 1.5 times ULN Other: * No frequent vomiting or medical condition (e.g., partial bowel obstruction) that would interfere with oral medication intake * No other prior or concurrent malignancy except surgically cured carcinoma in situ of the cervix or basal cell or squamous cell skin cancer * No uncontrolled infection * HIV negative * No AIDS-related illness * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No psychological, familial, sociological, or geographical condition that would preclude study PRIOR CONCURRENT THERAPY: Biologic therapy: * Prior cytokine via isolated limb perfusion for local-regional melanoma allowed * No other prior cytokine for metastatic melanoma * No concurrent colony-stimulating factors, including epoetin alfa or filgrastim (G-CSF) * No other concurrent immunologic or biologic therapy Chemotherapy: * Prior chemotherapy via isolated limb perfusion for local-regional melanoma allowed * No other prior chemotherapy for metastatic melanoma * No other concurrent chemotherapy Endocrine therapy: * Concurrent corticosteroids allowed during radiotherapy (arm II only) * No concurrent hormonal therapy Radiotherapy: * See Disease Characteristics * No other concurrent radiotherapy Surgery: * See Disease Characteristics * Recovered from the effects of any prior major surgery Other: * No other concurrent investigational drugs