First, the pancreas is a gland beneath the stomach that performs both exocrine and endocrine functions. It secretes enzymes for the digestion of food (exocrine), and it secretes hormones for important body functions (endocrine).
Pancreatic neuroendocrine tumors, or NETs, can be functional or non-functional. Functional tumors in the pancreas over-produce pancreatic hormones, such as gastrin, insulin, glucagon and somatostatin, and are named accordingly. Therefore, tumors that over-secrete insulin are called insulinoma; gastrin – gastrinoma.
But some pancreas tumors are non-functional, meaning they do not over-produce pancreatic hormones. Although they do not produce symptoms related to changes in hormones, they can still grown and cause problems.
Both functional and non-functional tumors may be associated with other tumors in the endocrine system. They are known as MEN syndrome or Multiple Endocrine Neoplasia.
Not all neuroendocrine tumors are cancerous. However, because these tumors over-secrete essential hormones, other serious conditions, such as diabetes can result and require medical/surgical treatment. There is currently no way to know which pancreatic NETs are cancerous without removing the tumor itself and looking at it under a microscope.
Non-functional NETs are more rapidly growing and are more likely malignant than functional pancreatic neuroendocrine tumors, but more research must be done in this area.
Symptoms of functional pancreatic tumors often mirror the symptoms of the body function the hormone is attempting to regulate. As an example, insulinoma or a pancreatic tumor that over-secretes insulin, may leave patients with symptoms of very low blood sugar – blurred vision, weakness, hunger, palpitations and seizures. Likewise, tumors over-secreting gastrin can cause abdominal pain, ulcers and diarrhea because of an increase in stomach acid.
Patients with non-functional pancreatic neuroendocrine tumors often present with abdominal pain, weight loss or jaundice. Unfortunately, these symptoms may not occur until the tumor has become large.
Some patients may have the pancreatic neuroendocrine tumor discovered incidentally during a CT scan being done for other reasons.
Pancreatic neuroendocrine tumors can be quite small, but they can often be detected using ultrasound and CT scans. Blood tests evaluating the various levels of pancreatic hormones in the body can be used to detect some functional tumors, as well as provide follow-up response to surgery or medicines.
Depending on the size, location and malignancy of the tumors, surgery is often the best course of action in treating these tumors. If the tumors are functional, surgery may be followed by medical therapies to reduce over-secretion of hormones that can give rise to uncomfortable or even serious symptoms.