Neuroendocrine tumors (NETs) represent a heterogenous group of unusual tumors, often slow-growing cancers. The neuroendocrine system consists of highly specialized neuroendocrine cells which act as an interface or junction between the endocrine system and the nervous system. The endocrine system is made up of cells whose function is to produce and secrete hormones into the bloodstream. Hormones are biochemical messengers that help to regulate many different processes within the body. The nervous system is composed of specialized cells (neurons) that control the activities of all body parts. A neuroendocrine cell is a cell which receives neuronal input (a signal from a nerve cell) and releases hormones in response to this signal.

The NETs are made up of neuroendocrine cells which are found in the respiratory and digestive tracts. Neuroendocrine cells are also located in endocrine glands, such as the adrenal glands, pancreas, thyroid and pituitary, ovaries and testes. Thus, there are a number of different types of NETs and they all have a slightly different way of presenting themselves, both in terms of symptoms and how they look under a microscope.

NET cancers can have a number of different effects on the body. Some NETs produce abnormally large amounts of hormones and some have a related syndrome, such as carcinoid syndrome, which means that the hormones that are secreted cause noticeable symptoms like flushing, diarrhea, cramps, asthma-like wheezing, heart problems and skin changes.

Depending on where they are in the body, NET cancers can give rise to a wide variety of symptoms. These symptoms may be mild or nonspecific, and are often similar to those of other, more common conditions. For example, many of the symptoms associated with carcinoid tumors are similar to those of Irritable Bowel Syndrome (IBS), Crohn’s disease, peptic ulcer disease, gastritis, other digestive disorders, asthma or pneumonia.

From a clinical standpoint, NETs can be divided in two groups: functioning and non-functioning. The functioning tumors will hypersecrete hormones that cause specific syndromes (e.g. carcinoid syndrome) and they are named according to the hypersecreted hormone (insulinoma, gastrinoma, etc.). The symptoms caused by the hypersecretion of these hormones often lead to their discovery. Nonfunctioning tumors, which account for about one-third to one-half of NETs, are not associated with a hypersecreted-related clinical syndrome. They come to attention because of their “mass effect” due to tumor bulk. Metastatic disease is usually present at diagnosis. Because they are usually slow growing, NETs are frequently diagnosed late in their course.

NET cancers are difficult to diagnose. After the onset of symptoms, which are often nonspecific and vague, a diagnosis can take an average of 5-7 years. If NET cancers are detected early in their development, they can often be cured with surgery. At present, however, most NET cancers are diagnosed at a later stage, when they have already spread to other parts of the body. In these cases, they can rarely be cured, although the symptoms can often be managed successfully for a number of years.

NET cancers may also spread (metastasize) to other parts of the body. The most common sites for these secondary cancers are the liver, bones and lymph nodes.

Carcinoid is classified as a rare cancer. Recent studies have determined that 4 to 5 out of every 100,000 people are diagnosed yearly with a neuroendocrine tumor and that there are between 12,000 and 15,000 people currently living with neuroendocrine tumors within Canada. Since most individuals with carcinoid are asymptomatic until the tumors metastasize, the average time between tumour development and diagnosis is between 5 to 10 years. Survival rates for individuals with carcinoid vary and depend on tumor type, location, extent of metastases, and many other factors. Currently, surgery is the only cure for localized tumors (those which have not spread) and there is no cure for metastatic carcinoid.

Many physicians are unfamiliar with NET cancers and therefore less likely to suspect a NET cancer in their initial investigations.

• The tumors are often small; some NET cancers can be less than a centimeter in size.
• NET cancers can occur almost anywhere in the body.
• The symptoms can vary enormously, and some patients have no symptoms at all.
• There are many different types of NET cancer, and a series of specialized tests is necessary. A biopsy is a definitive tool for a NET cancer diagnosis.

The treatment of a NET cancer depends on the size and location of the tumor, whether the cancer has spread, and the patient’s overall health. These are a complex group of cancers to manage, and, ideally, a multidisciplinary team of specialists will work with the patient to determine the best treatment plan.

Treatment Goals

• The primary goal of NET treatment is to remove the tumour by surgery. Depending upon the location of the primary tumor, or if the tumor has spread, this may not be possible.
• To alleviate symptoms
• To control the growth of the tumor
• To maintain a good quality of life for the patient

This section is still in construction. Please come back shortly for a more complete description of the disease.