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Somatostatin analogs for pNET symptoms

Somatostatin analogs are man-made compounds similar to somatostatin, a natural hormone in the body. They can help slow the growth of neuroendocrine tumor cells. They can be very helpful for patients with pNETs that have somatostatin receptors. When somatostatin analogs bind to the somatostatin receptors on cancer cells, they may stop the cancer cells from releasing hormones into the bloodstream, which can often relieve symptoms and help patients feel better. These analogs also seem to help slow the growth of some tumors but cannot cure them.

These drugs can help reduce side effects, such as diarrhea in patients with VIPomas and help the skin rash of glucagonomas. They, however, may not be as effective in treating low blood sugar in patients with insulinomas or treating increased stomach acid production in patients with gastrinomas.

They are very useful in people who have carcinoid syndrome (facial flushing, diarrhea, wheezing, rapid heart rate), although this syndrome is not as common with pNETs as it is with NETs found in other places.

• Octreotide (Sandostatin): One version of octreotide is short-acting and is injected 2 to 4 times a day under the skin. There is also a long-acting form of the drug (called Sandostatin LAR Depot) that only needs to be injected into a muscle every 4 weeks. Depending on the severity of symptoms, some people are given injections every day when first starting treatment. Once symptoms are controlled, the longer-acting monthly injection may then be used. Other times, the long-acting drug may be started from the beginning.
• Lanreotide (Somatuline Depot): This is a long-acting somatostatin analog. Most often, it is given every 4 weeks, by injection under the skin. Sometimes, your doctor might recommend this injection every 2 weeks.

Either drug may be given by your doctor or nurse, or you may learn how to give the injections at home.

Possible side effects of somatostatin analogs

The main side effects of these drugs are pain at the site of the injection, and rarely, stomach cramps, nausea, vomiting, headaches, dizziness, and fatigue. These drugs can also cause sludge to build up in the gallbladder, which can lead to gallstones that usually do not cause symptoms. They can also make the body resistant to the action of insulin, which can raise blood sugar levels and make pre-existing diabetes harder to control.

Other drugs used for specific pNET symptoms

Other drugs may be used to treat specific symptoms or problems caused by the excess hormone produced by pNETs.

Proton pump inhibitors

Gastrinomas make too much gastrin, which increases stomach acid levels, and can lead to stomach ulcers. Proton pump inhibitors, for example omeprazole (Prilosec), esomeprazole (Nexium), or lansoprazole (Prevacid), block stomach acid production and may be given to decrease the chance of ulcers forming.  

Diazoxide   

Insulinomas make too much insulin which causes very low blood glucose (sugar) levels. Diazoxide, a drug that keeps insulin from being released into the bloodstream, or diet changes (higher carbohydrate intake or more frequent meals) may be started to raise glucose levels.

Diabetes drugs

Glucagonomas make too much glucagon, a hormone that increases blood glucose (sugar) levels. It works the opposite of insulin. These cancers may be treated with diabetes drugs if somatostatin analogs alone are not enough to control the high glucose levels.

IV fluids

VIPomas make too much vasoactive intestinal peptide (VIP), a hormone that regulates water and mineral (such as potassium and magnesium) levels in the gut. Treatment may involve giving intravenous (IV) fluids to treat the dehydration from diarrhea as well as replace certain minerals that are low.