Other Drugs for Pancreatic Neuroendocrine Tumors

For people with advanced pancreatic neuroendocrine tumors (NETs), several medicines can help control symptoms and tumor growth. These drugs are used mainly when the tumor can’t be removed with surgery.

Somatostatin analogs

Somatostatin analogs are related to somatostatin, a natural hormone in the body. They can help slow the growth of neuroendocrine tumor cells. They can be very helpful for some patients with pancreatic NETs because these drugs stop tumors from releasing hormones into the bloodstream, which can often relieve symptoms and help patients feel better. They also seem to help slow the growth of some tumors, but cannot cure them.

These drugs can help reduce diarrhea in patients with VIPomas, glucagonomas, and somatostatinomas, help the rash of glucagonomas, and  lower the levels of insulin in insulinomas. 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 NETs in the pancreas as it is with NETs found in other places. The drugs are also helpful for people whose tumors show up on a somatostatin receptor scintigraphy (SRS) scan or gallium-68 Dotatate scans. 

• 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 given once a month, by injection into a muscle. 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 somatostatin analog is injected under the skin about once a month.

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

Possible side effects

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. 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. As a result, these drugs are only used to treat insulinomas if the tumor has somatostatin receptors as seen by a positive somatostatin receptor scintigraphy (SRS) or gallium-68 Dotatate scan. 

Other drugs used for specific pancreatic NETs

Somatostatin analogs can be used to treat most pancreatic NETs. But other drugs may be added to treat specific symptoms or problems that are caused by the excess hormone being produced by the cancer.

Gastrinomas make too make 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.     

Insulinomas make too much insulin which causes very low blood glucose (sugar) levels. If the somatostatin receptor scintigraphy (SRS) or gallium-68 Dotatate scans are negative, showing the cancer does not have the somatostatin protein, then other treatments besides somatostatin analogs are considered to even out glucose 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.

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

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 certain minerals that are low.