STUDYING RARE CANCERS IS very difficult because of their infrequency — making it harder to understand their biology and conduct clinical trials. However, a recent exception to this has been progress made in the treatment of neuroendocrine tumors, often referred to as NETs.
Unlike malignancies that develop in specific tissues and locations of the body, there are several different types of NETs. They can be seen in places such as the lungs and gastrointestinal tracts. In this special issue of CURE®, one of our features explores the revolution of treatment in this area. Although NETs have many presenting features, they don’t often show symptoms early in the disease process and are therefore often misdiagnosed or detected at more advanced stages.
NETs derive from neuroendocrine cells, which have the capacity to produce hormones that affect blood vessels, the lining of the intestinal tract and other tissues. Therefore, some NET cases can cause what is known as “carcinoid syndrome,” symptoms that include redness or warmth in the face or neck, diarrhea, shortness of breath, rapid heartbeat, high blood pressure, fatigue, weakness, abdominal pain, cramping and unexplained weight gain or loss.
NETs were launched into the mainstream due to one very famous case, that of Steve Jobs. The Apple CEO had a pancreatic NET, which was slow-growing — like most NETs — that allowed him to make health decisions at his own pace. He lived for years after his initial diagnosis, before succumbing to the disease in 2011. Since then, there has been a new era of treatments for these tumors that are helping patients live longer, and fairly well.
Many of these advances came from studying NETs at the genetic and biochemical levels. For instance, chemotherapy was widely used, but did not usually result in significant remissions, whereas Afinitor (everolimus), a drug that blocks a cell signaling pathway known commonly to be activated in NETs, has been shown to be effective although still not curative. Imaging technologies that use labeled precursors to the hormones produced by NETs are now valuable in diagnosing, staging and helping choose appropriate therapies. Advances in surgery techniques, plus a growing selection of targeted drugs approved by the Food and Drug Administration are boosting survival.
Successes in the management of NETs serves as an example of how to tackle the problem of studying rare tumors. Collaborations between medical centers and a focus on basic laboratory research are now being encouraged for a long list of rarer tumors, or less common subsets of the more prevalent cancers.
DEBU TRIPATHY, M.D. Editor-in-Chief
Professor of Medicine
Chair, Department of Breast Medical Oncology
The University of Texas MD Anderson Cancer Center