Internal Radiation Therapy in Treating Patients With Liver Metastases From Neuroendocrine Tumors

DISEASE CHARACTERISTICS: * Pathologically confirmed neuroendocrine tumor metastatic to the liver * Well-differentiated or moderately well-differentiated neuroendocrine tumors * Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm with conventional techniques or ≥ 10 mm with spiral CT scan * Symptomatic disease, meeting one of the following criteria: * Refractory carcinoid symptoms, defined as Carcinoid Symptom Severity scale \> 2 despite use of octreotide acetate at ≥ 200 mcg subcutaneously three times daily (or 20 mg intramuscularly once monthly) for ≥ 4 weeks * Evidence of radiographic progression with either of the following manifestations: * Moderate-severe right upper quadrant pain and unintentional weight loss \> 10% * Decline in Karnofsky performance status \> 10 points * At least a 20% increase in the sum of the longest diameters of target lesions in the liver within the past 12 months * No more than 75% replacement of normal liver by neuroendocrine tumor * No more than 20% arteriovenous lung shunting on a technetium Tc 99m macro-aggregated albumin nuclear scan * No equivocal, nonmeasurable, or nonevaluable liver metastasis PATIENT CHARACTERISTICS: * Karnofsky performance status 50-100% * Life expectancy ≥ 6 months * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Creatinine ≤ 1.5 mg/dL * Bilirubin ≤ 2.0 mg/dL * Albumin ≥ 3.0 g/dL * Absolute granulocyte count ≥ 1,500/mm³ * Platelet count ≥ 65,000/mm³ * Hemoglobin \> 9.0 g/dL * INR ≤ 1.4 * No hepatic arterial anatomy that would preclude the administration of study treatment into the liver * No nonmalignant disease that would preclude study participation * No other malignancy within the past 5 years except for cured basal cell carcinoma of the skin or cured carcinoma in situ of the uterine cervix PRIOR CONCURRENT THERAPY: * Prior surgery, chemotherapy, or locally ablative technique for the liver cancer allowed * No prior radiotherapy to the upper abdomen that includes the liver in the treatment field * No investigational drug or agent/procedure (i.e., participation in another clinical trial) within the past 4 weeks * No other specific anticancer treatment (other than octreotide acetate) during and for 3 months after completion of study therapy