This is not a medical description, but we have tried to explain this in simplified terms. Not to lose any meaning, but so that the average person might be able to understand it.
NeuroEndocrine Tumors (NETs) are a collection of various cancers arising from the neuroendocrine system. They are fairly similar, so the differences in diagnosis and treatment are often similar (but not always exactly the same). Of the NETs, Carcinoids make up about 75% of all NETs and they can arise from anywhere in the body, although there are some places more likely than others.
A lot of people lump all NETs into the term “Carcinoid”. In fact, most patients call themselves “noids”, for short. If you tell someone you have a NET, they think you might be catching butterflies, where as Carcinoid is easier to recognize.
Carcinoid was first observed in 1904 and was called “cancer in slow motion”.
Symptoms
Many patients do not have symptoms. Some develop them as the disease progresses. The degree of symptoms is not a good indicator of how far the disease has progressed, as NETs located in various parts of the body bypass the liver and distribute the hormones directly into the bloodstream, causing symptoms early on.
One of the complications in diagnosing Carcinoid/NETs is that the symptoms that may be present are often vague, and quickly attributed to more common diseases. Diarrhea is one of the more troublesome problems that can occur. Aside from the inconvenience, frequent diarrhea can lead to dehydration and loss of body electrolytes. Flushing is one of the more common symptoms. Doctors, who are taught to think of common things, will likely contribute it to Rosacea or some other malady. Sometimes flushing can be brought on while drinking alcoholic beverages, especially red wine.
Other common symptoms include abdominal pain, which can be referred (projected) to the back our shoulders; histamine release; variations in blood pressure and/or heart rate; shortness of breath, often attributed to asthma.
Many patients are incorrectly diagnosed as having Irritable Bowel Syndrome (IBS). Frequent bowel obstructions can also indicate a tumor in the intestinal tract.
Female patients often get the double whammy of being told they are going through menopause, or some variant of it. Many often get asked if they have emotional problems, stress at work, or other psychological conditions are hinted at.
As you can see, nailing down a diagnosis for Carcinoid/NETs can be about as easy as trying to nail Jello to the wall. Add to that many doctor’s reluctance to think of a “rare” disease and you can see why so many go mis or undiagnosed for years.
Now, more about the disease.
There are some doctors who think that Carcinoid/NETs are not really cancer. The general definition of a cancer is something that grows and can metastasize. Carcinoid/NETs do both of those.
Carcinoid/NETs are cancer, but they are different from other cancers. They require treatments that can work if applied to more common cancers, but applied to NETs can make them thrive. This is why having a true Carcinoid/NET specialist is so critical. You will probably have a lot of well meaning friends and family directing you to information and advice that applies to more common cancers. Sadly they don’t understand the special nature of what you are dealing with.
As an example, let’s look at the passing of Steve Jobs in late 2011. Mr. Jobs had a Pancreatic Neuroendocrine Tumor (PNET), named so for the place of the primary tumor, the pancreas. Yet the media kept reported him as dying of the more well-known pancreatic cancer. Even their attempts to correct the information were off base. One well known publication flat out stated that Mr. Jobs did not have pancreatic cancer, but rather a PNET. They then went on in the article to compare pancreatic cancer (not a PNET) to other common cancers.
Dr. Rodney Pommier has called Carcinoid the “upside down cancer”. Think of a pyramid diagram, kind of like the old FDA food pyramid. Most cancers start with a primary tumor which begins to grow. As they grow, they expand out in size (the base of the pyramid). They then continue to grow at the base and extend into nearby tissue, moving up toward the top of the pyramid. They finally have some distant metastases, which are less in size (the top of the pyramid) than the rest of the cancer.
Carcinoid is the same pyramid, yet upside down…the point is at the bottom. The primary tumor (at the bottom) can remain small and hidden (think grain of rice) and never get larger. Yet it will then seed out to nearby tissue and finally metastases, which grow to be the largest part of the cancer. The primary tumor is still small, but it has seeded out so much cancer.
So how does carcinoid/NETs hurt me?
For all your life, your body produces various hormones that perform different functions. With carcinoid/NETs, the tumors cause your body to produce excess amounts of these normal hormones…too much of a good thing. Some of these hormones can cause damage all by themselves. For example, Serotonin is commonly overproduced by NETs. Serotonin causes tissue to become fibrotic (hard and grainy, like scar tissue). It then causes heart valves to fail to seal properly as they lose their elasticity.
Different types of NETs can produce different hormones. The tumors can even change what hormones they produce over the life of the cancer. Having so many hormones to choose from makes diagnosis difficult. Having a full panel of hormones tested at some point, even if none are high, can become a baseline for future tests should any become elevated (“well, it was X back in 2003, now is Z”)
Another way the NETs hurt patients is that they often metastasize to the liver. In fact, most patients are found with, and because of, these liver “mets”. Unlike other cancers, liver mets in NETs are more manageable than and not as critical as for the more common cancers. There are a number of treatments available to deal with these “mets”. Following the trends of standard liver function tests are usually of little value, as the liver is able to compensate with these tumors. It is not until late in the disease that liver function becomes compromised enough to show up on those tests.
A less common way is that the tumors can restrict flow through a blood vessel, causing compromise of some organ or area in the body. The tumors can often cause pain should they press against nerves or irritate organs.