What tests are carried out to diagnose pancreatic cancer?

This section lists common tests that may be performed and it is not necessary for all the tests to be performed for a patient. Your doctor will select the tests that will assist him /her to have the maximum information about the tumor/ disease.

A CT scan is a type of x-ray that gives a picture of organs and other structures (including any tumours) in your body. It is used to see more details of a cancer and its relation to the surrounding organs in your body. It also gives information related to cancer spread into the lymph nodes, liver or lungs.

CT scans can help tell if your cancer has spread into lymph nodes or other organs such as your liver. They can also be used to guide a biopsy needle precisely into a suspected area of cancer spread. For a CT-guided needle biopsy, the patient remains on the CT scanning table, while a doctor moves a biopsy needle in the body toward the location of the mass. CT scans are repeated until the doctor is sure that the needle is in the mass. A fine-needle biopsy sample (tiny fragment of tissue) or a core-needle biopsy sample (a thin cylinder of tissue about ½-inch long and less than 1/8-inch in diameter) is then removed and looked at under a microscope.

This test is like a CT scan, but it uses magnetism instead of x-rays to build up pictures of the organs in your abdomen. Like a CT scan, MRI is painless and the magnetism is harmless. MRI scan may be used to see the extent of blockage of bile duct and in case the patient is allergic to contrast dye injection used for CT scans.

This test uses an endoscope with a small ultrasound probe on the end. This probe releases sound waves and then detects the echoes that bounce off tissues of the digestive tract wall. A computer then translates the pattern of echoes into an image of the wall of the esophagus, stomach, intestine, or rectum. Putting the ultrasound probe on the end of an endoscope lets it get very close to the tumor. Because the probe is close to the area being studied, it can make very detailed pictures. EUS can be used to see how deeply a tumor may have grown into the wall of the esophagus, stomach, intestine, or rectum. Endoscopic ultrasound can also help see if certain lymph nodes are enlarged and help a doctor guide a needle into a lymph node, tumor, or other suspicious area to do a biopsy.

Even if an imaging test finds a mass, it cannot tell if the mass is a neuroendocrine tumor, some other type of tumor or cancer, or an area of infection. The only way to know for sure is to remove cells from the abnormal area and look at them under a microscope. This procedure is called a biopsy.

There are several ways to take a sample from a gastrointestinal tumor. One way is through the endoscope. When a tumor is found, the doctor can use a biopsy forceps (pincers or tongs) through the tube to take a small sample of it. Another way to sample a tumor is with a CT-guided needle biopsy, as was described in the section on CT scans.

Scans using small amounts of radioactivity and special cameras may be helpful in looking for neuroendocrine tumors. They can help determine the extent of the tumor, as well as help locate it if doctors aren’t sure where it is in the body.

OCTREOSCAN: Somatostatin receptor scintigraphy, also known as OctreoScan, is the scan most commonly used to look for neuroendocrine tumors. It uses a hormone-like substance called octreotide that has been bound to radioactive indium-111. Octreotide attaches to proteins on the neuroendcorine cells. A small amount of this substance is injected into a vein. It travels through the blood and is attracted to neuroendocrine tumor cells. About 4 hours after the injection, a special camera is used to show where the radioactivity has collected in the body. More scans may be done over the next few days as well.

A positron emission tomography (PET) scan is another imaging test that uses low levels of radioactivity to look for tumors. For most diseases, PET scans use a form of radiolabelled glucose (sugar) to find tumors. But when it is used to look for neuroendocrine tumors/cancers, PET uses a radioactive form of 5-hydroxytryptophan (5-HTP), a chemical that is taken up and used by neuroendocrine cells. A special camera can detect the radioactivity. Some doctors have found PET scans to be more accurate than CT scans for detecting spread of disease. However, this technique is not available in every hospital.

Tests of the blood and urine can be very helpful in diagnosing carcinoid syndrome in patients who have symptoms that may be caused by it.
Serotonin (also called 5-HT) is a substance made by many carcinoid tumors, especially those in the small intestine. It is probably the cause of at least some of the symptoms of carcinoid syndrome. The body breaks it down into 5-hydroxyindoleactic acid (5-HIAA), which is released into the urine. A commonly used test to look for carcinoid syndrome measures the levels of 5-HIAA in a urine sample collected over 24 hours.

Eating foods that contain a lot of serotonin can raise 5-HIAA levels in the urine. Such foods include, bananas, plantains, kiwi, certain nuts, and avocado. Medicines, including cough syrup and acetaminophen (Tylenol), can also affect the results. These substances should be avoided before urine and blood testing for carcinoids.

Other commonly used tests to look for carcinoids can include blood tests for chromogranin A (CgA), and gastrin. Depending on the where the tumor might be located and on the patient’s symptoms, doctors may do other blood tests as well.
Some of these tests can also be used to show how well treatment is working, since the levels of these substances tend to go down as tumors shrink.

What are the common symptoms of neuroendocrine tumor?

Most tumors grow slowly and produce vague symptoms that are more often caused by something else. When trying to figure out what’s going on, doctors and patients are likely to explore other, more common possible causes first. This can delay a diagnosis, sometimes even for several years.

The symptom a person develops from a gastrointestinal neuroendocrine tumor often depends on where it is located. Pancreatic neuroendocrine tumors are most often non-functional and are often detected incidentally. Functional tumors produce hormones and are responsible for symptoms for eg Insulinoma produces insulin and lowers blood sugar levels, Gastrinoma produces gastrin and causes hyperacidity, VIPoma produces a peptite that is reposnsible for severe and oft repeated diarrhoea.

People with tumors/cancers in their appendix often don’t have symptoms. If it is discovered, it is often when they have their appendix removed during an operation for some other problem.

If the tumor/cancer starts in the small intestine, it can sometimes kink or block the intestines, causing abdominal pain. This pain can be mild and last for a couple of years or more before the carcinoid tumor is found. Often a tumor needs to grow fairly large before it blocks (obstructs) the intestine. When that happens, patients have severe abdominal pain, nausea and vomiting.

Sometimes, a tumor may cause intestinal bleeding. This can lead to anaemia (low red blood cell counts) with fatigue and shortness of breath. These same problems can also occur with carcinoid tumors that start in the colon. Rectal carcinoid tumors are often found during routine exams, even though they can cause pain and bleeding from the rectum.

Carcinoid tumors that develop in the stomach usually grow slowly and often do not cause symptoms. They are sometimes found during an exam of the stomach by endoscopy that is done to look for other things. Some can cause symptoms such as the carcinoid syndrome.

Carcinoid syndrome: In about 1 out of 10 cases, carcinoid tumors release enough hormone-like substances into the bloodstream to cause symptoms. This results in the carcinoid syndrome. Symptoms include:

• Facial flushing (redness and warm feeling)
• Severe diarrhea
• Wheezing
• Fast heartbeat

The diffuse neuroendocrine system

Our body has some different types of cells that behave like nerve cells in certain ways and like hormone-making endocrine cells in other ways. These cells do not form an actual organ, instead, they are scattered throughout other organs like the oesophagus, stomach, pancreas, intestines, and lungs. The digestive system is large and contains more neuroendocrine cells than any other part of the body.

Neuroendocrine cells help control the release of digestive juices and how fast food moves in the GI tract. They may also help control the growth of other types of digestive system cells.

Neuroendocrine tumors

Like most cells in the body, GI tract neuroendocrine cells sometimes go through certain changes that cause them to grow too much and form tumors. These tumors are known as neuroendocrine tumors (NET) and neuroendocrine cancers. In the past, most abnormal growths of neuroendocrine cells were called carcinoids. But in 2000, the World Health Organization (WHO) reclassified carcinoids into neuroendocrine tumors and neuroendocrine cancers.

Neuroendocrine tumors are growths that look benign (i.e not cancerous) but that might possibly be able to spread to other parts of the body. Neuroendocrine cancers are abnormal growths of neuroendocrine cells which can spread to other parts of the body.

Neuroendocrine cancers (also known as neuroendocrine carcinomas) can then be divided into groups based on the way the cells look under the microscope. A cancer with cells that do not look very abnormal is called well differentiated. These tumors tend to be less aggressive. They grow and spread slowly. Well differentiated neuroendocrine cancers can look identical to benign neuroendocrine tumors when examined under the microscope. Sometimes the only way to know for certain that a mass is a neuroendocrine cancer (and not a benign tumor) is when it spreads to other organs or tissues. If the cells of a cancer look very abnormal, it is called poorly differentiated. These cancers tend to be more aggressive meaning that they grow and spread quickly.

Neuroendocrine tumors can be classified as functional and non-functional.

Neuroendocrine tumors and cancers act like the cells they come from, often releasing certain hormone-like substances into the bloodstream. These excess hormones are responsible for producing symptoms. As example of this is that a tumor in the pancreas may produce a hormone called insulin. This hormone is normally responsible for keeping the blood sugar levels under control. An excess of this hormone can cause a drastically low blood sugar levels and a person may have repeated fainting episodes. Such a tumor is then named after its hormone producing substance viz Insulinoma. This is then labelled as a functional tumor. A Gastrinoma is responsible for producing gastrin, that secretes excess of stomach juice and is responsible for severe acidity.

In contrast; non-functional tumors do not produce hormones. These tumors can go undetected for a long time and may come to notice once they have attained a large size and are often found incidentally during investigations for some other reason.

In general, neuroendocrine tumors and neuroendocrine cancers grow more slowly than other cancers in the GI tract. But how they grow and whether or not they spread to other areas varies widely. This depends to some extent on which part of the body the tumor starts in.