ISLET CELL TUMORS
Islet cell tumors of the pancreas are rare tumors and approximately 2500 cases of pancreatic islet cell tumors are seen in the United States each year. These tumors are often also called pancreatic neuroendocrine tumors.
Islet cell tumors of the pancreas are different from adenocarcinoma of the pancreas. These tumors are derived from neuroendocrine cells and tend to be slow growing tumors that are treatable even after they have metastasized. Islet cell tumors can produce dramatic symptoms since up to half of these tumors may secrete hormones that produce side effects due to excessive secretion of the hormones.
What are the different types of islet cell tumors?
The following types of islet cell tumors are recognized:
The following types of functional islet cell tumors are recognized
Non-functioning islet cell tumors
Non-functioning islet cell tumors are being identified more frequently because of widespread availability of CT scan imaging. These tumors have a histological appearance of islet cell tumors but do not produce any symptoms since they do not release excessive amounts of hormones in the blood.
Because these tumors are clinically silent and do not produce any hormones, they can grow silently for a long time before they are discovered. More than 50% of all non-functioning islet cell tumors are malignant (cancerous) and at the time of diagnosis the tumors are typically large and easily localized by CT scanning or MRI.
Work-up of non-functioning islet cell tumors at USC
At USC non-functioning endocrine tumors are worked up with the following studies:
Treatment for non-functioning islet cell tumors
Surgical removal of non-functioning islet cell tumors is often curative. Our patients are therefore evaluated for surgery and all attempts are made to try and completely remove the tumor. The type of surgery depends on the location of the tumor. These tumors typically tend to be large and therefore enucleation of the tumor is usually not possible.
For tumors located in the head of the pancreas, a Whipple operation is usually indicated whereas for tumors in the tail of the pancreas a distal pancreatectomy is required. For very small tumors, organ preservation procedures such as a pancreatic head resection or a spleen preserving distal pancreatectomy may be possible options.
Our approach is to remove these tumors preferentially by laparoscopic surgery. An open procedure is usually offered to the patient if there is presence of metastases, for very large tumors (greater than 10 centimeters), if there is invasion of the major blood vessels around the pancreas by the tumor, and by patient preference. For all other patients, the laparoscopic procedure is offered as the treatment of choice.
Functioning islet cell tumors
Functional islet cell tumors often present in a dramatic fashion due to secretion of excessive amounts of hormones such as insulin, gastrin, or glucagon. These tumors tend to present at a very early stage when the tumor is tiny and is often not readily detectable.
Localization of these tumors is an important consideration since the tumors may be very small, only a few millimeters in size, when the patient presents with major symptoms related to over secretion of the hormones.
Pre-operative tests performed to detect the functioning islet cell tumors:
The following studies are offered at USC for detecting functioning islet cell tumors
Treatment of functioning neuroendocrine tumors
The different types of functioning neuroendocrine tumors require special consideration for surgery. Surgery is tailored to the type of the tumor. For further details click on the following links:
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