What’s New in Gastrointestinal Carcinoid Tumor Research and Treatment?
There is always research going on in the field of gastrointestinal (GI) carcinoids. Scientists keep looking for the causes of, ways to prevent, and new approaches to diagnose and treat GI carcinoid tumors.
Researchers are looking for the causes of GI carcinoid tumors in the hope that this knowledge can be used to help prevent or treat them in the future. A great deal of progress has been made in recent years. For example, scientists have found that changes in the MEN1 gene (the gene that causes multiple endocrine neoplasia, type 1) are seen in many people with GI carcinoids. Other genetic changes that seem to make tumors more aggressive are now being explored as well.
Diagnosis and staging
Because the outlook and treatment of GI carcinoid tumors and other cancers of the digestive tract are very different, accurate diagnosis is important. Researchers have made great progress in developing tests that can detect specific substances found in the cells of carcinoid tumors. Most of these tests treat tissue samples with special antibodies made in the lab. The antibodies are designed to recognize specific substances that appear only in certain types of tumors.
OctreoScan® is an imaging test commonly used to look for GI carcinoid tumors in the body. Researchers are now looking at other radionuclide methods to see if they can detect carcinoid tumors early.
Surgery is the main treatment option for carcinoid tumors when possible. But better approaches are needed when surgery can’t remove all of the tumors. Chemotherapy has had limited success. New chemotherapy drugs and combinations of drugs are being studied, but true advances are likely to come from other approaches.
Several newer types of drugs, known as targeted therapies, are now being studied for use against neuroendocrine tumors. Targeted therapy uses drugs or other substances to identify and attack cancer cells while doing little damage to normal cells. These therapies attack the parts of cancer cells that make them different from normal, healthy cells. Each type of targeted therapy works differently, but all alter the way a cancer cell grows, divides, repairs itself, or interacts with other cells.
Everolimus (Affinitor®) is a targeted drug that works by blocking a cell protein known as mTOR, which normally helps cells grow and divide. It is approved by the FDA to treat advanced pancreatic neuroendocrine tumors. It is also being studied to see if it can help patients with GI carcinoids. In one study, adding everolimus to octreotide (Sandostatin) was better than octreotide alone in halting tumor growth.
Bevacizumab (Avastin®) is a type of targeted drug that attacks a tumor’s blood supply. It is already being used against some types of cancer and is being studied for carcinoid tumors.
Other targeted therapies block the molecules that increase the growth of cancer cells. Some of these (such as erlotinib, temsirolimus, and sorafenib) are used in other types of cancer and are now being tested against carcinoids.
Netazepide is new drug that blocks the hormone gastrin. In early studies of patients who have carcinoid tumors of the stomach and high gastrin levels, this drug helped the tumors shrink. More studies are planned.
Radionuclide scans, such as the I-131 MIBG scan, can help find neuroendocrine tumors because they use substances that are attracted to neuroendocrine cells. These substances are attached to slightly radioactive elements so that they can be detected with special cameras. Using higher doses of I-131 MIBG delivers more radiation to the tumor cells and is used in Europe to treat neuroendocrine tumors and cancers. But doctors are now studying the use of a form of octreotide (or a similar drug called edotreotide) that has been attached to a radioactive form of the element yttrium called 90-Y. When injected into the body, the drug homes in on the tumor cells, allowing the radiation from the 90-Y to kill them. So far, results have been promising, but this approach is still only available in the United States as a part of a clinical trial.
Last Medical Review: February 26, 2015 Last Revised: February 8, 2016