Pancreatic islet cell carcinoma

Overview
Cancer of the endocrine pancreas includes a highly treatable and often curable collection of tumors. They are uncommon cancers with 200 to 1,000 new cases per year and occur in only 1.5% of detailed autopsy series. Islet tumors may either be functional (produce one or more hormones) or nonfunctional. The majority of functioning tumors that produce insulin are benign; however, 90% of non-functioning tumors are malignant.

There is no detailed or generally accepted staging system for islet cell cancer; however, a logical division of these tumors follows:


 * Islet cell cancers occurring in one site.
 * Islet cell cancers occurring in several sites.
 * Islet cell cancers metastatic to regional lymph nodes or distant sites.

Many islet cell cancers are nonfunctional and produce symptoms from tumor bulk or metastatic dissemination. Because of the presence of several cell types in the pancreatic islet cells (alpha, beta, delta, A, B, C, D, E), the term islet cell tumors refers to at least five distinct cancers, which when functional, produce unique metabolic and clinical characteristics.

Since the clinical manifestations in functional tumors may result from the metabolic effects of polypeptide(s) secreted by the cancer cells rather than from tumor bulk or metastatic disease, each tumor type must be considered separately, both diagnostically and therapeutically.[1-3] Functional tumors may be too small in size to be detected by conventional imaging techniques.

The frequent long delays between initial symptoms and diagnosis and the varied effects of the polypeptides secreted often necessitate involvement of multiple surgical and medical subspecialties.

Surgery is the only curative modality.[4,5] Even in those cases not resectable for cure, effective palliation may be achieved because of the slow-growing nature of the majority of these tumors and the potential use of antihormonal pharmacologic therapy (for example, cimetidine in the ulcer-producing Zollinger-Ellison syndrome).

Combination chemotherapy may provide effective palliation as well as increased survival in selected patients. In patients with indolent, slow-growing metastatic islet cell tumors, the best therapy may be careful observation and no treatment until palliation is required.

Patients with multiple endocrine neoplasia syndrome type 1, an autosomal dominant condition in which 85% have pancreatic islet cell tumors, 90% have hyperparathyroidism, and 65% have pituitary tumors, are less likely to be cured by pancreatic resection than are patients with sporadic islet cell tumors. With the exception of pain relief from bone metastases, radiation therapy has a limited role in this disease.