Location of gastrinomas by means of portal venous sampling is a technique in which venous blood from various sites in the portal system around the pancreas and duodenum is obtained and assayed for gastrin levels. A gradient of 50% or greater compared to systemic gastrin levels from a given location regionally identifies the site of gastrin overproduction, thereby locating the tumor. The only area in which venous sampling may help, in the authors' opinion, is in the small subset of patients who have occult gastrinoma not imaged with any other modality, in the body or tail of the pancreas that cannot be found with intraoperative ultrasound or palpation. It is considered that a secretin angiogram is equally effective and is a simpler procedure. Similarly, in insulinoma regional location of the tumor by means of a calcium angiogram has eliminated the usefulness of portal venous sampling.
Controversial areas of surgical treatment of APUDomas often reflect a balance between the risks and benefits of aggressive surgery, as data to support an aggressive surgical approach to obtain improved survival often do not exist. For example, if patients with occult MTC can undergo cervical reexploration with minimal or no morbidity the potential benefit of removing malignant disease, warrants this approach. Similarly, if patients with MEN-1 can be explored safely with resection of pancreatic and duodenal tumors, then this position can be defended. On the other hand, if a subgroup of patients with MEN-2 and pheochomocytomas can be spared bilateral adrenalectomy without compromising their long-term outcome in terms of disease-free survival, then this conservative approach is warranted. For all of these controversial areas long-term follow-up of these patients with relatively indolent malignancies may support other current therapeutic recommendations. 0 I 993 Wiley-Liss, Inc.*