Carcinoid Tumor

Carcinoid tumors are fairly rare cancers that can occur most commonly in the intestine and lungs.

Carcinoid tumors are not very common. These cancers arise from cells in the body that produce certain hormones. Carcinoid tumors most often develop in the intestine or lungs. In some cases, the cancers cause symptoms such as bleeding, pain, and Intestinal Obstruction because of their size and location. In other cases, symptoms such as flushing, Diarrhea, and Low Blood Pressure are caused by the release of large amounts of hormones by these cancers. However, these symptoms usually do not occur until the cancer has spread to the liver. Carcinoid tumors can develop anywhere within the intestinal tract (from the stomach to the rectum). They are most often found in the appendix. Far less frequently, they develop outside the intestinal tract, with the most common site being the lungs. The treatment for this disease depends on the size and location. If the tumor is small and has not spread to other parts, then it can often be surgically removed. Once the tumor has spread to the liver, treatment is primarily aimed at decreasing symptoms. Long-term prognosis depends on whether or not the cancer has spread to the lymph nodes or liver.

For more details regarding Carcinoid Syndrome, please see the section "Carcinoid Syndrome."

Carcinoid tumors often do not cause any significant symptoms until late in the disease process. That is, they grow slowly and do not cause any problems for a long time. In fact, because they are slow growing and often cause only vague symptoms, the average time between onset of symptoms and diagnosis is 4 to 5 years.

Symptoms that can be caused by intestinal carcinoid tumors include gastrointestinal bleeding, bowel obstruction, Intussusception, or abdominal pain, depending on their location and size. However, these symptoms can also be due to many other diseases.

Also, in some cases, the cancer spreads to the abdominal cavity and triggers a reaction that causes the lining of the abdomen to become very thick and hard. This can also cause bowel obstruction and stomach pain.

Other symptoms include nausea, fatigue, and weight loss.

If the cancer spreads to the liver, then one can develop Carcinoid Syndrome, which is caused by hormones released from the cancer cells. The symptoms include flushing, Diarrhea, Low Blood Pressure, wheezing, and sometimes problems with the heart valves. For more details, see the section on Carcinoid Syndrome.

People with bronchial carcinoid tumors (these are carcinoid tumors that develop in the lungs) usually have wheezing, frequent Pneumonias, and a cough (including coughing blood). If the cancer blocks one of the air passages, then one may feel short of breath.

In a few cases of bronchial carcinoid tumors, the cancer is located in the very outer part of the lungs and may not cause any symptoms at all.

People with pulmonary carcinoid tumors usually do not have the symptoms associated withCarcinoid Syndrome because these tumors grow slowly and only rarely metastasize (or spread) to the liver.

The cause of carcinoid tumors is not known. They develop because of the uncontrolled replication of certain cells. However, what causes this abnormal growth is not known.

90% of all carcinoid tumors develop in the intestinal tract. They can develop almost anywhere throughout the intestinal tract, all the way from the stomach to the rectum. The most common locations are the appendix, intestine, and stomach.

Another common location for carcinoid tumors is the lung. These tumors usually occur in men and women equally and most people with the cancer are less than 60 years old.

Other less common sites for the development of carcinoid tumors include the thymus, bile ducts, breast, and ovary. Also, carcinoid tumors are sometimes a part of the MEN (multiple endocrine neoplasia) Type I syndrome.

Approximately half of all carcinoid tumors develop in the appendix. Cancers that develop in this location are usually benign. They may spread locally, but rarely do they spread to distant sites.

Rectal carcinoid tumors (carcinoid tumors that develop in the rectum) are also usually benign.

However, carcinoid tumors that develop in the small intestine are usually more malignant. They have a higher tendency to spread both locally as well as to metastasize to other parts of the body, including the liver.

Carcinoid tumors that develop in the lungs are potentially malignant and can spread locally as well as to distant sites. However, they are considered to be less aggressive than tumors that develop in the small intestine.

Carcinoid tumors usually spread to the lymph nodes and liver. However, they can also spread to the bone, heart, breast, or eye.

Carcinoid tumors that develop in the thymus may be associated with Hyperparathyroidism or with Cushing's syndrome.

The chance of metastasis depends on the size of the tumor. If it is smaller than 1 cm, then it rarely metastasizes. If it is bigger than 2 cm, then almost 100% of the time it has spread.

As stated above, diagnosis is often delayed several years because the symptoms can initially be vague. Also, the characteristic symptoms of Carcinoid Syndrome only occur after the cancer has spread to the liver.
Once the diagnosis is suspected, several tests can be done. Certain tests can be done to identify the location of the tumors.

Endoscopy - in this test a camera is used to look into the stomach and the first part of the intestine, or it can be used to look at the large intestine. This test can also be used to do biopsies (in which a piece of the tumor is removed so that it can be analyzed in the laboratory).
CT scan - this test can help identify larger tumors and can also see if there is any spread to the liver.
Barium studies - in this test a dye is administered and X-Rays are taken of the intestinal tract. This may help identify tumors.

In addition to CT scan, abdominal Ultrasoundand Angiography (in which a dye is injected into blood vessels) can be used to see if the cancer has spread to the liver.

A nuclear medicine scan can also be done if all else fails. This test uses a substance that is absorbed by carcinoid tumor cells. With this test you can see any areas that take up large amounts of the substance.

Bronchial carcinoids can be diagnosed by Bronchoscopy (in which a camera is inserted into the lungs) or by CT scan.

In almost all cases, even though cancer is suspected, the only way to confirm the diagnosis is by performing a biopsy. For cancers within the intestinal tract, biopsies can be done with endoscopy. For cancers that have spread to the liver, a Liver biopsy can be done. For cancers in the lung, a biopsy can be done by either Bronchoscopy or by a lung biopsy.

If one has symptoms of Carcinoid Syndrome, then blood and urine tests for 5-HIAA (5-hyroxyindolacetic acid) can be done. Carcinoid tumors secret a substance known as serotonin. This substance is then converted to 5-HIAA and excreted in the urine.

Since most people with Carcinoid Syndromewill have an elevated urine 5-HIAA level, this the most useful test.

Some people with Carcinoid Syndrome may have normal urinary 5-HIAA levels. In these cases, they may need to have their blood serotonin levels measured to make the diagnosis.

Also, in some cases of gastric carcinoid tumors, very little 5-HIAA is formed. Therefore, other lab tests such as 5-HTP levels, urine serotonin levels, or histamine levels may need to be checked.

Sometimes, the diagnosis is unclear, as when the patient complains of flushing but the doctor has not seen it. In such cases, medicines, such as alcohol, pentagastrin, or extremely low doses of epinephrine can be given to cause flushing.

Bananas, plantains, pineapples, kiwi fruits, walnuts, plums, pecans, avocados, guaifenesin, and acetaminophen can elevate 5-HIAA levels. Aspirin and levodopa can decrease 5-HIAA levels. Therefore, these variables must be taken into account when checking 5-HIAA levels.

There are no definite risk factors for the development of carcinoid tumors.

However, certain conditions such as Hashimoto's Thyroiditis, MEN (multiple endocrine neoplasia) syndrome Type I, pernicious anemia, and achlorhydria all are associated with a higher chance of developing carcinoid tumors.

Treatment depends on whether or not Carcinoid Syndrome is present and the severity of the symptoms.
Because most people with Carcinoid Syndrome have metastatic disease to the liver, surgery is not really an option.
If symptoms are not too severe, they can be controlled with certain medications.

For Diarrhea, medicines such as loperamide, diphenoxylate/atropine, cyproheptadine, or methysergide can be used.
For flushing, treatment is given if the symptoms are frequent or severe. Medications that can be used include anti-histamines (such as diphenhydramine) along with anti-ulcer medications (such as ranitidine). These two medicines in combination can help reduce the flushing.
Another medicine called phenoxybenzamine can also be used to help reduce the flushing.
People with wheezing and trouble breathing caused by lung carcinoids can be treated with steroids and medicines such as theophylline. Inhalers such as albuterol should be avoided because they can make the symptoms worse.
One of the most effective drugs used in treating people with Carcinoid Syndromeis octreotide. It can reduce the wheezing, flushing, and Diarrhea associated with the disease in over 75% of the people. It can also be used to treat the Low Blood Pressure that can sometimes occur with this disease. It does not treat any heart valve problems associated with the disease and it is not clear whether it decreases the fibrosis caused by the disease. The other problem with octreotide is that it has to be given either intravenously or by injections several times a day.

Surgical removal of the cancer is the best treatment for tumors from the appendix or large intestine that are less than 2 centimeters in size.
Carcinoid tumors from other parts of the intestinal tract are also surgically removed if the cancer has not spread. However, remember, the diagnosis of carcinoid tumors is usually delayed. The vast majority of people have liver involvement by the time the diagnosis is made. In a few cases where only one metastatic lesion is found in the liver, removal of the cancer and the metastatic liver lesion results in some improvement of survival. However, in the majority of cases, surgery may temporarily reduce symptoms, but does not change the long-term outlook. Thus, in most cases, surgery is usually not performed for intestinal carcinoid tumors.
In some people with Carcinoid Syndrome due to a tumor in the lung or other site outside the intestine, they may be cured if the tumor is removed.
There are also other treatments that have been tried for carcinoid tumors. The problem is that these cancers generally do not respond to chemotherapy or to radiation therapy. Therefore, these are not very good options.
Certain therapies do reduce the size of the tumor as well as the symptoms. However, these treatments do not really change the long-term prognosis. These include:

Hepatic artery embolization - in this procedure, the blood supply to the tumor is cut off by blocking the artery. In 90% of people, this will reduce the symptoms temporarily. Complications of this treatment include pain, fever, and problems with liver function. Also, symptoms of Carcinoid Syndrome may increase temporarily after the procedure.
Local radiation therapy - this is often not very effective because these tumors are often resistant to radiation therapy.
Selective hepatic artery chemotherapy infusion - in this procedure, an angiogram is performed to see which artery is feeding the cancer. Then, chemotherapy is given into that specific artery in an attempt to destroy the cancer. However, as mentioned above, carcinoid tumors are often very resistant to chemotherapy.

Newer treatments are being studied. Hopefully, research will result in more options in the future.

In some people with bronchial carcinoid tumors as well as carcinoid tumors outside the intestinal tract, surgical removal is an option even if they have Carcinoid Syndrome. Radiation therapy and chemotherapy are not options because these treatments usually do not work. .

In a few cases of bronchial carcinoid tumors, no treatment is needed. They can simply be followed with serial CT scans.

The long-term outlook depends on the area where the cancer develops, the size of the cancer, and whether or not it has metastasized.

Carcinoid tumors that develop in the appendix or rectum are usually very slow growing and rarely affect long-term survival.

For carcinoids that develop in other parts of the intestine or stomach, the 5-year survival is 95% if it has not spread, 65% if it has only spread to the local lymph nodes, and about 20% if it has metastasized to the liver.

Once the person has developed flushing, survival on average is about 2 to 3 years. Also, the higher the urine 5-HIAA levels, the worse the prognosis.

If the tumor spreads to the liver, then it can lead to Carcinoid Syndrome and its associated complications.

Bronchial carcinoid usually does not invade locally or metastasize. Complications are usually from bleeding and from airway obstruction.

Other complications from intestinal carcinoid tumors include abdominal pain, intestinal bleeding, Intestinal Obstruction, bowel infarction, or Intussusception. Also the cancer can spread to the lining of the intestine and cause it to become thick and hard (fibrotic).