Tests for Small Intestine Cancer (Adenocarcinoma)

Small intestine cancers are often found because of signs or symptoms a person is having. But these symptoms aren’t usually enough to know for sure if a person has a small intestine cancer or some other type of health problem. If a tumor is suspected, exams and tests will be needed to confirm the diagnosis.

Medical history and physical exam

When a doctor takes your medical history, you will be asked about your symptoms, possible risk factors, family history, and other medical conditions. The doctor will then examine you, focusing on your abdomen looking for any swelling or sounds of the bowel trying to overcome a blockage.

Blood tests

If your doctor suspects a small intestine cancer, they will likely order some blood tests, such as:

• A complete blood count (CBC), which measures the levels of red blood cells, white blood cells, and platelets. Small intestine cancer often causes bleeding into the intestines, which can lead to a low red blood cell count (anemia).
• Blood chemistry tests to look for signs that a cancer might have spread to the liver, or other problems.

Imaging tests

Imaging tests use x-rays, magnetic fields, or radioactive substances to create pictures of the inside of the body. Imaging tests might be done for a number of reasons, including:

• To help determine if symptoms are being caused by a tumor
• To learn how far cancer has spread
• To help determine if treatment is working
• To look for signs that the cancer has come back

Most patients who have or may have a small intestine tumor will have one or more of these tests.

Barium x-ray tests

For these tests, a liquid containing barium (a chalky substance) is put into the body to coat the lining of the gastrointestinal (GI) tract, and then x-rays are taken. The barium helps outline any abnormal areas in the esophagus, stomach, and intestines, making them more visible. These x-rays are most often used to look for tumors in the upper or lower parts of the GI tract, but they are less helpful in finding small intestine tumors. Barium tests were used more often before endoscopy was available (see below).

• Upper GI series: For this test, you will be given a barium liquid to drink, and then x-rays are done to look at the upper part of the digestive tract (the esophagus, stomach, and first part of the small intestine). To look for problems in the rest of the small intestine, more x-rays can be taken over the next few hours as the barium passes through the intestines. This is called a small bowel follow-through. This test often gives good pictures of the first part of the small intestine (the duodenum), but the rest of the small intestine may be hard to see in detail.
• Enteroclysis: This test gives more detailed pictures of the small intestine than the upper GI series with small bowel follow-through. A thin tube is passed down the nose or mouth, through the stomach, and into the small intestine. Then barium is sent through the tube directly into the small intestine. X-rays are taken as the liquid moves through the small intestine.
• Barium enema (lower GI series): This is a way to look at the large intestine (colon and rectum). Before this test, the bowel needs to be cleaned out. This is done by using strong laxatives and enemas the night before and the morning of the exam. For this test, the barium solution is given into the large intestine through a flexible tube that is put into the anus (like an enema). For better pictures, air can also be injected into the intestine through a tube. This is called air contrast. This procedure is meant to be used to look at the large intestine, but sometimes the last part of the small intestine can be seen as well.

Computed tomography (CT) scan

A CT scan uses x-rays to make detailed cross-sectional images of your body. Unlike a regular x-ray, a CT scan creates detailed images of the soft tissues in the body.

CT scans are often done if you have abdominal (belly) pain to try to find the source of the problem. Although small intestine tumors may not always be seen well on a CT, these scans are good at showing some of the problems that these tumors can cause (like an obstruction or perforation). CT scans can also help find areas of cancer spread.

CT enteroclysis: This test is sometimes used to get a better view of the intestine than a standard CT can provide. Before the scan, a thin tube is passed down your nose or mouth and down to the small intestine. A large volume of a liquid contrast agent is then put into the tube, which helps expand the intestine and makes it easier to see on a CT scan.     

CT-guided needle biopsy: CT scans can also be used to guide a biopsy needle precisely into an abnormal area that could be cancer spread. For this procedure, called a CT-guided needle biopsy, you will stay on the CT scanning table while the doctor moves a biopsy needle through the skin and toward the location of the mass/tumor. CT scans are repeated until the needle is within the mass. Small samples of tissue are then removed and looked at under a microscope.

Magnetic resonance imaging (MRI)

Like CT scans, MRI scans show detailed images of soft tissues in the body. But MRI scans use radio waves and strong magnets instead of x-rays. 

MRI scans can sometimes be useful in people with suspected small intestine tumors, because they can show a lot of details in soft tissues. But a CT scan is often done instead, as it is typically an easier test to have done.

MR enteroclysis: This test is sometimes used to get a better view of the intestine than a standard MRI can provide. Before the scan, a thin tube is passed down the nose or mouth and down to the small intestine. A large volume of a liquid contrast agent is then put into the tube, which helps expand the intestine and makes it easier to see on an MRI.     

Endoscopy

For an endoscopy, the doctor puts a flexible, lighted tube (endoscope) with a tiny video camera on the end into the body to see the inner lining of the GI tract. If abnormal areas are found, small pieces can be biopsied (removed) through the endoscope.

Upper endoscopy

Upper endoscopy (also called esophagogastroduodenoscopy or EGD) is used to look at the esophagus, stomach and duodenum (the first part of the small intestine). The endoscope is put in through the mouth, and then passes through the esophagus, into the stomach, and then into the first part of the small intestine. If the doctor sees any abnormal areas, small pieces of tissue can be removed to be looked at under a microscope to see if cancer is present.

Most people having this test are given medicine to make them sleepy. If this is the case, you will usually need someone to take you home (not just a cab or rideshare service).

This test is helpful in looking at the first part of the small intestine. Other tests, such as capsule endoscopy and double-balloon enteroscopy, are needed to look at the rest of the small intestine.

Capsule endoscopy

This procedure does not actually use an endoscope. Instead, you will swallow a capsule (about the size of a large vitamin pill) that has a light and a very small camera. Like any other pill, the capsule goes through the stomach and into the small intestine. As it travels through the small intestine (usually over about 8 hours), it takes thousands of pictures. The camera sends the images to a device that you wear around the waist while going about your normal daily activities. The pictures can then be downloaded onto a computer, where the doctor can look at them as a video. The capsule passes out of the body during a normal bowel movement and is flushed away.

Double-balloon enteroscopy (endoscopy)

Most of the small intestine can't be viewed with an upper endoscopy because it is too long (about 20 feet) and has too many curves. Double-balloon enteroscopy gets around these problems by using a special endoscope that is made up of 2 tubes, one inside the other.

You are given intravenous (IV) medicine to help you relax, or even general anesthesia (so that you are asleep). The endoscope is then inserted either through the mouth or the anus, depending on if there is a specific part of the small intestine to be looked at.

Once in the small intestine, the inner tube, which is an endoscope, is pushed forward a small distance, and then a balloon at its end is inflated to anchor it. Then the outer tube is pushed forward to near the end of the inner tube and it is then anchored in place with a balloon. This process is repeated over and over, letting the doctor see the intestine a foot at a time.

This test can sometimes be helpful when done along with capsule endoscopy. An advantage of this test over capsule endoscopy is that the doctor can biopsy anything that looks abnormal.

Because you will be given medicine to make you sleepy for the procedure, usually someone you know will need to drive you home (not just a cab or rideshare service).

Biopsy

Procedures such as endoscopy and imaging tests can find areas that look like cancer, but the only way to know for certain is to do a biopsy. In a biopsy, a piece of the abnormal area is removed and looked at under a microscope.

There are different ways to take biopsy samples of an intestinal tumor.

• A biopsy can be done during an endoscopy. When a tumor is found, the doctor can use biopsy forceps (pincers or tongs) through the tube to take small samples of the tumor. The samples are very small, but doctors can usually make an accurate diagnosis. Bleeding after a biopsy is a rare but potentially serious problem. If bleeding becomes a problem, doctors can sometimes inject drugs that constrict blood vessels through the endoscope and into the tumor to stop the bleeding.
• For some patients, surgery is needed to biopsy a tumor in the intestines. This may be done if the tumor cannot be reached with an endoscope.
• Sometimes CT scans or other imaging tests are used to guide a thin, hollow needle to biopsy tumors in other organs (like the liver) to see if they are cancer.

Lab tests of biopsy samples

Doctors can usually tell if a biopsy sample contains cancer (adenocarcinoma) cells by looking at it under a microscope. But other tests might be done on the samples as well. 

For example, the cancer cells might be tested for certain gene changes that could affect treatment options. Changes in mismatch repair (MMR) genes, or another genetic change known as microsatellite instability (MSI), make it more likely that the cancer might respond to treatment with immunotherapy drugs called checkpoint inhibitors.