Expertise in laparoscopic surgery for Insulinoma & Neuro endocrine Tumours

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What do the terms ‘Neuro endocrine tumors’, ‘Islet cell tumor’ and ‘Carcinoid’ mean?
All these tumors arise from similar cells with origins from neural tissue which form part of the endocrine system and produce and release hormones. Hence these are called Neuro Endocrine Tumors (NET) or more accurately Gastro-Entero-Pancreatic-Neuro Endocrine Tumors (GEP-NETs). They have two distinct groups: Pancreatic Endocrine Tumors (PET) and Carcinoid.

What is Pancreas? What has it got to do with the endocrine system?
The pancreas is a major gland that lies behind the stomach. It is attached at its head to the small intestine, where it releases powerful enzymes that aid in digestion (exocrine function). Distributed inside the pancreas are multiple tiny islands like endocrine glands (Islets of Langerhans). These make several important hormones, related to digestive organs, which are released into the bloodstream (endocrine function). These hormones control blood sugar levels, sugar consumption, stomach acid production, intestine fluid production, etc.

What are Pancreatic Endocrine Tumors?
Tumors of these endocrine glands (Islets of Langerhans) are called Islet cell tumors or Pancreatic Endocrine Tumors (PET). All these are rare tumors. There is a surprising array of hormones that islet cell tumors have been found to make; some are not even related to the pancreas. This array includes insulin, gastrin, glucagon, somatostatin, neurotensin, pancreatic polypeptide ("PP"), vasoactive intestinal peptide ("VIP"), growth hormone releasing factor ("GRF"), ACTH and others. These tumors are named after the predominant hormone made by them:

Insulinoma (most common of these rare islet cell tumors)
  Non-functioning tumors: these have no symptoms and may include tumors which produce PP ("PPomas") or neurotensin ("neurotensinoma”), as these hormones usually produce no symptoms.

What is Insulinoma?

As explained above, Insulinoma is a tiny insulin hormone producing tumor in the pancreas. The excess insulin hormone produced by it dangerously lowers the blood sugar levels. This is the opposite of diabetes where there is an insulin deficit and high blood sugar.

How does it manifest?
A desire to eat frequently, and stomach discomfort when hungry may be due to an insulinoma. Fasting is followed by sweating, dizziness, confusion and sometimes even fits and loss of consciousness. This is often mistaken for epilepsy and treated unsuccessfully with anti-epileptic drugs. These symptoms can be avoided by frequent snacking and are relieved by glucose. Other general symptoms include episodic sweating, tremors, palpitations, nausea, persistent hunger, weight gain.

How do you test for it?
The insulinoma can be diagnosed by checking blood sugar and insulin levels after many hours of starvation or during an episode of altered consciousness. The blood sugar will be very low and the insulin level high. C peptide and other tests are also done.

These tumors are less than 15mm (1/2 inch) in size and hence difficult to locate. Various sophisticated tests are used to locate these tiny tumors including: Contrast Enhanced CT scan (CECT), MRI scan, Somatostatin Receptor (octreotide) Scintigraphy (SRS), Endosonography, selective arteriography, selective portovenous sampling and portal venous sampling with intra-arterial calcium stimulation.

How is it treated?
In most hospitals a major part of the pancreas is removed surgically as the insulinoma is too small to be identified by an inexperienced surgeon. As Pancreas is a very important organ for both digestion and preventing diabetes, every effort should be made to conserve it. A well defined insulinoma can be easily removed without sacrificing the pancreas provided it is identified. We are able to identify and specifically remove such an insulinoma even by laparoscopic surgery so that the patient recovers rapidly and returns to normal activity. If an insulinoma is not well defined we localize it by the various sophisticated methods listed earlier. We have pioneered a method of conserving the pancreas even in such patients. This kind of minimal pancreas surgery avoids converting a person from a state of excess insulin (insulinoma) to a state of severe insulin deficit (labile diabetes) which is difficult to manage. Complications are uncommon under the expert care of an experienced surgeon. Sometimes the problem may not be localized (Nesidioblastosis) and a part of the pancreas may have to be removed by open surgery. Only about 10% of these tumors are cancers and need extensive removal followed by anti cancer medication.

What about Neuro endocrine tumors other than Insulinoma?

Most of the other islet cell tumors have fairly similar characteristics in spite of the different hormones made by them. These similarities include symptoms like diarrhea, sweating, anxiety, headache, fatigue etc. Many of these tumors are large (except Gastrinoma). Most are cancers requiring extensive surgery and additional treatments like hormone therapy, chemotherapy, biologic therapy (immunotherapy), etc.

Gastrinoma over produces the hormone gastrin. It causes Zollinger-Ellison syndrome, a combination of severe peptic ulcer disease, acidity and excess gut fluids. About 2% of patients with peptic ulcers that do not heal even after receiving an appropriate treatment, are found to have a gastrinoma tumor. This tumor is tiny like an insulinoma and the same tests (see insulinoma) are used to locate it. Unlike other islet cell tumors it often occurs outside the pancreas especially in the duodenum (initial part of small intestines). The surgery for it is similar to that for insulinoma except that it involves an extensive search even outside the pancreas.

Glucagonoma over produces the hormone glucagon, which has an effect opposite of insulin. Glucagonoma presents with mild diabetes and a unique kind of skin rash and patches that spreads on the face, groin, or lower extremities.

Somatostatinoma may or may not produce somatostatin, a hormone that inhibits the secretion of several other hormones (such as growth hormone, insulin, and gastrin). It may present with Diabetes, Gallstones, Steatorrhea (oily and loose stools with a particularly bad odor), Diarrhea, Weight loss, etc. Sometimes it may be associated with jaundice, low glucose levels, multiple swellings under the skin (Neurofibromatosis), etc.

VIPoma is also called Verner-Morrison syndrome. It over produces the hormone vasoactive intestinal peptide (VIP) that plays a role in water transport in the intestines. Excessive amounts of VIP can cause chronic, watery diarrhea, Flushing (redness in the face, neck, or chest), etc.

Carcinoid is usually so slow-growing that initially it was thought to be "cancer-like" rather than a cancer, and hence named canceroid. It is the most common of the Neuro endocrine tumors. It can originate from pancreas, lungs, thymus, appendix, ovaries, etc. The presentation of Carcinoid tumors depend on their location, size, spread to liver and other organs and release of hormones to the rest of the body. Carcinoid tumors can secrete any number of hormonal, growth and other factors. Symptoms may be intermittent and vague. Common presentation is periodic abdominal pain sometimes accompanied by flushing (redness) of the face, palpitations, severe diarrhea, and an episode of asthma. Heart valves can undergo permanent damage.

Tests are done for serotonin, 5-HT, catecholamines, histamine, and urinary 5-HIAA. Various scans are required to locate the tumor and any spread elsewhere.

Small Carcinoid tumors of the stomach or colon can often be completely removed through an endoscope. Other small Carcinoids need limited surgery e.g., Carcinoid in the appendix needs just an appendectomy. A large tumor or a tumor that has spread elsewhere needs extensive surgery and additional treatments like hormone therapy, chemotherapy, biologic therapy (immunotherapy), etc. Tumor spread to liver is managed by various methods like chemoembolization, radiofrequency ablation, cryotherapy, etc. Patients should avoid alcoholic drinks, stress, strenuous exercise, spicy foods, and certain medicines that can make the symptoms of Carcinoid worse.

Copyright 2008