Neuroendocrine cells are located all throughout our body – from our digestive and respiratory systems to our brain and adrenal glands. They release hormones that help each system function properly: In the digestive system, they help break down food; in the respiratory system, they help control breathing; in the adrenal glands, they help regulate cortisol levels.
When a neuroendocrine tumor develops, the symptoms it produces depends upon where the tumor is located. Unlike other cancers (breast, colorectal, lung and prostate for example), there isn’t a specific set of symptoms that signify a neuroendocrine tumor. And sometimes, there can be no symptoms at all for a long time. Not only that, but symptoms that do occur can masquerade as other illnesses.
“In general, we think it takes on average five to seven years to get diagnosed with neuroendocrine cancer after presenting with symptoms,” says Philip A. Philip, M.D., Ph.D., a medical oncologist at Henry Ford Health. “But even then, the cancer could have been slowly growing for 15 – 20 years before that. It’s just the nature of the malignancy. Neuroendocrine cancer is a slow-growing tumor compared to other cancers. We also do not have screening tests like we have for breast and colorectal cancer.”
The Sneaky Symptoms Neuroendocrine Tumors Can Produce
Most neuroendocrine tumors do not produce signs or symptoms until they’re at a more advanced stage. If they’re found before that, it’s usually incidentally.
Here, Dr. Philip shares symptoms to watch out for that can present as other issues:
- Carcinoid syndrome. About 20 – 30% of people who have a neuroendocrine tumor in the lungs, or in the small bowel that has traveled to the liver, can experience the symptoms of carcinoid syndrome. These include diarrhea, flushing, wheezing and heart palpitations. “Carcinoid syndrome can go unnoticed for a while because you can chalk up these symptoms to other conditions,” says Dr. Philip. “Diarrhea could be confused with irritable bowel syndrome or inflammatory bowel disease. Flushing can be confused with postmenopausal symptoms. And I myself get palpitations from drinking a lot of coffee.”
- Hypoglycemia. Hypoglycemia – or low blood sugar – mainly occurs in those whose neuroendocrine tumor originates in the pancreas. The tumor produces too much insulin, and insulin lowers blood sugar. It causes symptoms like lightheadedness, fainting and in severe cases, coma.
- Hyperglycemia. Hyperglycemia – or high blood sugar – can also be a symptom of a pancreatic neuroendocrine tumor. In this case, the tumor causes the pancreas to produce too much of a hormone called glucagon, which raises blood sugar. Symptoms of hyperglycemia include headaches, increased thirst, fatigue, increased urination and blurry vision.
- Stomach ulcers. In the stomach or upper gastrointestinal tract, neuroendocrine tumors can increase the amount of a hormone called gastrin. Gastrin makes the stomach produce acid, which can cause ulcers to develop. But like the above symptoms, stomach ulcers don’t obviously signify a neuroendocrine tumor either – as stomach ulcers can develop from a variety of factors, from stress to an H. pylori infection or from taking NSAIDs (over-the-counter pain relievers like ibuprofen and aspirin.)
When the tumor gets big enough - if it’s located in the digestive system - it can cause bowel obstruction and abdominal distention. Other general symptoms of advanced neuroendocrine cancer include fatigue and weight loss.
Treating Neuroendocrine Cancer Isn’t One Size Fits All
A diagnosis of neuroendocrine cancer can be confirmed through blood and urine tests, along with imaging and biopsies. Depending upon a variety of factors such as its stage and where the tumor originated, treatments can include:
Neuroendocrine Cancer Care at Henry Ford Health
- Surgery to remove the tumor
- Chemotherapy to destroy tumor cells
- Targeted radioactive drugs to destroy tumor cells (called peptide receptor radionuclide therapy, or PRRT)
- Hormone therapy to limit the tumor’s growth and prevent it from secreting hormones
“Because no neuroendocrine tumor is alike, we have a highly specialized way of assigning treatment each patient,” says Dr. Philip. “We have a tumor board that includes a variety of specialists to discuss cases and develop patient-tailored treatment recommendations. We’re the only healthcare system in Michigan that does this for neuroendocrine tumors. It’s a rare cancer and many people have limited experience in it. In one day, I see in my clinic the number of patients a community doctor will see in a year.”
The Rarity of Neuroendocrine Cancer
Because neuroendocrine cancer is rare, there’s limited information on genetic and environmental risk factors. Unlike lung, breast, colorectal, cervical and prostate cancer, for example, which have clear screening guidelines and known factors that increase someone’s risk of developing the disease, the same cannot be said for neuroendocrine cancer.
That said, if you have neuroendocrine cancer, there are clinical trials you can enroll in, which may not only help improve your outcome but also move research forward about this disease.
Reviewed by Philip A. Philip, M.D., Ph.D., F.R.C.P., an internationally renowned medical oncologist specializing in gastrointestinal cancers. He is the Chief, Division of Hematology/Oncology in the Department of Internal Medicine at Henry Ford Health. He has led numerous studies in the areas of gastrointestinal tumors. He sees patients at Henry Ford Cancer in Detroit and Henry Ford Medical Center – Columbus.
