Surgical treatment of rare endocrine tumors

Neoplasms of the endocrine pancreas are rare, with an incidence approximating five cases per one million person-years. The nationwide registration of the pancreatic neoplasm in Japan (Table 65.1) shows that the most frequent is nonfunctioning tumors, followed by insulinoma, glucagonoma, gastrinoma, pancreatic endocrine tumor associated with multiple endocrine neoplasia-1 (MEN-1) and others [1]. Out of 5,432 registered patients in leading hospitals in Japan, 100 cases (1.8%) harbored nonfunctioning tumors. Other types of endocrine tumors represent less than 1% of all cases. Since a limited number of referral hospitals have the experience of treating islet cell tumors, it is very important to draw a whole picture using a nationwide registry. The locus of the tumor does not correlate with the histological or hormonal characteristics, as shown in Table 65.2. Although the islets are distributed throughout the pancreas, the tumor does not always show a multifocal nature even in hereditary MEN-1, suggesting a multistep tumorigenesis rather than a simple genetic alteration. As shown in Table 65.3, the clinical symptoms of rare endocrine tumors tend to be very subtle or nonspecific compared to insulinoma, resulting in the silent growth of the tumor. In this chapter, surgical treatment based on the pathophysiological background of the rare endocrine tumors including two inherited types (MEN-1 and Von Hippel-Lindau, VHL) and nonfunctioning tumors will be described. Every type of pancreatectomy, including enucleation, should be applied to minimize the surgical risk, but we will focus on the case of an advanced endocrine tumor in the head of the pancreas to show the typical surgical treatment.