This study will examine the safety and effectiveness of interferon-a and octreotide for the treatment of Zollinger-Ellison syndrome (gastrinoma) and advanced non-B islet cell cancer. Gastrinoma is a tumor produced by the pancreas that secretes the hormone gastrin, which in turn stimulates production of gastric juices that cause ulcers. Some of these tumors are malignant. Gastrinomas that have spread and cannot be surgically removed require drug treatment (chemotherapy). Current drug regimens, however, provide only temporary benefit and, in some cases, produce life-threatening side effects. In studies of patients with tumors similar to gastrinoma, the drugs octreotide and interferon-a, alone or in combination, showed some effect in stopping tumor growth and were better tolerated than chemotherapy. At least one-third of patients responded to treatment with either drug for at least 6 months; the two drugs given together may produce a better response than either one alone.

Patients currently enrolled in an NIH study of Zollinger-Ellison syndrome whose gastrinoma has spread from the original site and cannot be surgically removed may be eligible for this study.

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.

Patients will be admitted to the hospital for the first day or two of therapy to be monitored for side effects and to learn how to self-inject the drugs to continue therapy at home. Both drugs are given [Note: how often? once a day, twice a day, weekly?] (Octreotide is also available in long-acting form, and patients who prefer may be given this drug once a month by the doctor.)

During the treatment period, patients will be seen by their personal physician every 2 weeks for the first month and once a month thereafter for a medical evaluation and check of adverse side effects of treatment. In addition, they will be admitted to the NIH Clinical Center once every 3 months for a medical evaluation and imaging studies, including CT, MRI, ultrasound, bone scan, and octreoscan, to assess the effect of treatment on tumor size.