A Revolution in the Treatment of Neuroendocrine Tumors

Patients with neuroendocrine tumors have more treatment options than ever before.
NETs, which are also called carcinoid tumors, can occur in many parts of the body because they begin in the neuroendocrine cells, which are widely disbursed and responsible for producing hormones. NETs occur most commonly in the lungs and gastrointestinal (GI) tract, although they can also appear in the thyroid, adrenal or pituitary glands. About 8,000 people in the United States are diagnosed with GI NETs every year and 4,000 with lung NETs, according to the American Society of Clinical Oncology (ASCO).

No obvious causes or avoidable risk factors have been found for NETs, according to ASCO. Most patients receive a diagnosis after age 60. Five-year survival rates can be as high as 90 percent when the tumors haven’t spread to distant organs or lymph nodes.

NETs are difficult to diagnose because they often cause no symptoms or they produce symptoms that don’t readily point to cancer. About 20 percent of NETs cause abnormal hormone secretions, sometimes referred to as carcinoid syndrome, which can result in a variety of symptoms. If an intestinal NET causes too much of a hormone called serotonin to be released, for example, patients can get flushing or diarrhea. A NET on the pancreas can cause excess production of insulin and glucagon, which can make blood sugar hard to control. And carcinoid syndrome in the lungs can cause asthma-like symptoms, such as a cough or wheezing.

Keeping Hormones Under Control

NETs possess receptors for somatostatin, a hormone that occurs naturally in the body and regulates the production of other hormones. Synthetic versions of somatostatin, called Somatuline (lanreotide) and Sandostatin (octreotide), are often prescribed to patients with NETs as injections every two weeks or monthly to control carcinoid syndrome.

Ronny Allan, a patient in the United Kingdom who was diagnosed with a metastatic NET in his small intestine in 2010, got his carcinoid syndrome symptoms under control with Somatuline. It took three surgeries to remove most of the cancer, and Allan’s disease has been declared stable — meaning none of his remaining tumors are growing.

Allan believes he may owe his positive prognosis to Somatuline, which has been shown in several studies to have some antitumor effects in addition to controlling carcinoid syndrome. In 2014, the FDA approved the drug for tumor control in patients with gastrointestinal or pancreatic NETs, based on a clinical trial in which progression-free survival (PFS) for patients on the drug was more than 22 months compared with 16.6 months for patients on placebo.

Somatostatin analogs can cause side effects like intestinal malabsorption and fatigue — symptoms that sometimes feel like carcinoid syndrome — says Allan, 61, a retired management consultant who blogs about his experiences, but it’s worth it. “I’m quite fortunate that my quality of life is good,” Allan says. “There’s been so much development. A lot of us are living longer.”

Depending on the location and size of NETs, surgery can offer the best chance for a cure, and new imaging techniques are making it easier to spot and evaluate NETs. One commonly used imaging technique is Octreoscan, in which a mixture of octreotide and the radioactive particle indium-111 is injected into the bloodstream. The drug latches onto the NETs’ somatostatin receptors, causing the tumors to light up.

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