Participants will be admitted to the NIH Clinical Center for blood and urine tests, electrocardiogram (EKG), chest X-ray and imaging studies (CT, ultrasound, MRI, octreoscan, and bone scan) before beginning treatment to evaluate the size and extent of tumors. Patients will then start interferon-a or octreotide, or both, given as injections under the skin. Treatment will continue for at least 6 months, unless side effects require stopping the drugs early. Patients whose tumors shrink or remain stable may continue treatment indefinitely. Those who do not respond to treatment will be taken off the study and offered standard chemotherapy.