Evaluation and Treatment of Non-functional Neuroendocrine Tumors

Non-functioning pancreatic neuroendocrine tumors are a specific type of endocrine tumors in which the cells do not produce any biologically active hormones.  These tumors may secrete substances that do not result in clinically measurable symptoms (pancreatic polypeptide, neurotensin, or calcitonin).  Studies have shown that 10-25% of all pancreatic neuroendocrine tumors are non-functional, with some suggesting that this number may be as high as 50%.  As a result, non-functional tumors are one of the most common type of pancreatic neuroendocrine tumors.

The main features of non-functional pancreatic neuroendocrine tumors are larger size at the time of diagnosis (4 cm on average) due to lack of clinical symptoms other than those associated with pain, obstruction or bleeding. Because they are often discovered later in the disease course, non-functional tumors more often have traveled elsewhere in the body at the time of diagnosis  (60-80%). They can be located anywhere in the pancreas and are typically associated with elevated chromogranin A and pancreatic polypeptide levels in the blood.  These substances are often helpful in tracking extent of disease and monitoring patients for recurrence after surgery.

Symptoms typically associated with non-functioning neuroendocrine tumors of the pancreas

Most patients present with symptoms related to the size of the tumor.  These include abdominal pain, weight loss, or jaundice.  Abdominal pain is the most common but is often non-specific.

Radiographic studies utilized in the evaluation of non-functioning neuroendocrine tumors of the pancreas

A CT scan or MRI is usually necessary to evaluate the location of the tumor and determine if there has been any spread of tumor outside the immediate area of the tumor.  For many years, octreotide scans were utilized to image patients with neuroendocrine tumors. Newer types of functional imaging studies, such as PET CTs and DOTATATE scans are now being utilized more often. In particular, DOTATATE scans have increased sensitivity for identifying tumor not able to be identified on other types of imaging studies.

Treatment of non-functioning neuroendocrine tumors of the pancreas

Surgery is the primary mode of treatment.  Operations that may be recommended include enucleation, distal pancreatectomy +/- splenectomy, or pancreaticoduodenectomy (Whipple procedure).  Surgery offers the best chance for long-term cure but may not be recommended if significant metastatic disease is found. There is a role for debulking tumor in some patients, and this is determiend on a case by case basis.

Metastatid non-functional neuroendocrine tumors

Nonfunctional tumors have an approximate 60-80% chance of metastasis.  This is largely due to a delay in diagnosis as many patients may not have any symptoms until the tumor has already spread elsewhere in the body.

Prognosis for non-functional neuroendocrine tumors

The 5-year survival in patients diagnosed with non-functional pancreatic neuroendocrine tumors is approximately 50%.  This may be slightly worse than in patients with functional pancreatic neuroendocrine tumors (production of insulin, gastrin, glucagon, somatostatin, vasoactive intestinal peptide).