Carcinoid Syndrome in Patients With NETs

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Andrew E. Hendifar, MD: Functional tumors can often produce different symptoms in our neuroendocrine tumor patients. The most common syndrome is a carcinoid syndrome, which occurs almost exclusively in midgut tumors that secrete serotonin. We usually identify these tumors through further imaging with gallium Ga 68-DOTATATE PET [positron emission tomography] or CT [computed tomography] imaging. The diagnosis of carcinoid syndrome, though, is made only after a careful H&P [history and physical examination], or history of and present illness of the patient, talking to them about their symptoms and understanding if the patient does, in fact, have diarrhea and flushing.

Oftentimes, we can follow these patients serologically using either a serum 5-HIAA [5-Hydroxyindoleacetic acid] test or a 24-hour urine collection, which can give us an idea of serotonin and how that’s changing from time to time. This syndrome is really characterized by diarrhea. It usually occurs in an ascending history, where the patient will note that they’ve had maybe 1 bowel movement a week for a few years, which will increase to 1 bowel movement a day, which then increases to several bowel movements a day. The diarrhea can be quite debilitating. It can create issues for our patients’ quality of life, where they no longer can attend many events that they’re used to attending. It can adversely affect them in that way.

The flushing is to be distinguished from other types of flushing. It tends to be dry. It’s very red. It’s episodic. It lasts only for a certain period of time. It doesn’t last for a very long time. The flushing can also be associated with other sensations such as dizziness and light-headedness. But the flushing can honestly be quite embarrassing and can also impact quality of life in a negative way. Patients don’t like to be told, “Is everything OK? You look very red. You look very flushed.” It can be quite embarrassing.

The cornerstone of treatment for carcinoid syndrome is somatostatin analogue therapy. This is given in long-acting forms. In addition to that, other maneuvers can be done to treat carcinoid syndrome. They can be given peptide receptor radiotherapy. They can take short-acting somatostatin analogue therapies. They can also take a new medication, telotristat ethyl, which is an oral tryptophan hydroxylase inhibitor that can also help manage the diarrhea associated with the carcinoid syndrome.

Supportive care for our carcinoid patients is very important and essential to their optimal management. I think dietitians can really help in the management of this disease. They can help guide patients on what foods to eat and what foods to avoid. They can also help with the inevitable need to replace pancreatic enzymes, in how that’s best done. Somatostatin analogue therapies can often lead to pancreatic exocrine insufficiency, and it’s very important to tease out the different types of diarrheas and help the patient actually feel and get better.

Transcript Edited for Clarity