Biologic behavior of sporadic gastrinoma located to the right and left of the superior mesenteric artery.

Among a series of 107 closely followed patients with gastrinoma, 60 patients with sporadic type tumors were identified and evaluated. There were 44 patients (73%) with tumors to the right of the superior mesenteric artery (SMA). Of these, 16 (36%) had extrapancreatic tumors, 28 (64%) had tumor within lymph nodes, and 9 (20%) had multiple tumors. In this group of patients, there were 19 (43%) cures, and only 9 (20%) patients had hepatic metastases. In contrast, in 16 patients (27%) with tumors to the left of the SMA, there were no extrapancreatic tumors, only 3 patients (19%) had tumor within lymph nodes, and 7 (44%) had multiple tumors. In this group, there was only one cure (6%), and nine (56%) patients had hepatic metastases. These findings suggest two distinct populations of sporadic gastrinoma, one to the right (gastrinoma triangle) and the other to the left (outside triangle) of the SMA, which appear to have different biologic behaviors. These differences may reflect divergent etiologies for these two groups of tumors.