Diagnosing Pancreatic Cancer
The most important tests used to detect pancreatic cancer are imaging tests such as Ultrasounds, CT scans and MRI scans. These tests use a variety of methods to see inside the body. Imaging tests can be simple x-rays or more complex scanning methods that use computers to reconstruct the structures in the body.
Computed Tomography (CT) Scan
A CT scan, also called a CAT scan is a sensitive imaging test used to evaluate patients suspected of having pancreatic cancer and can produce three-dimensional images of the pancreas. It is estimated that this type of CT scan can diagnose about 98% of all pancreatic cancers and distant metastases.
Many people are familiar with or have had a computed tomography (CT) scan. During a CT scan, you will lie on a table that is moved into the machine. The scanner will take detailed and cross-sectional x-ray images from many different angles. This test may take up to 2 hours and can be done on an outpatient basis.
A CT scan is a painless procedure. The only discomfort of CT scanning is the lying down flat for a few minutes. This may be of no consequence to most individuals but can be discomforting to those with neck and back problems. In addition, the CT scan does tend to cause a claustrophobic feeling because of the closed space enclosure.
Sometimes a dye, known as a contrast agent, can be injected into a vein but is usually given by mouth in order to produce better CT images of body structures such as the stomach and small intestines. In many centres, basic CT scanners are modified to see the pancreas more accurately. When contrast is used, the individual may feel warm all over the body during the injection. This is a short lasting painless feeling. Others may complain of a metallic taste in the mouth. The rare individual may develop an allergy which may be associated with hives and itching.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging is another imaging method that is in common use today, and many people are familiar with it. This procedure is painless and does not require you to drink anything special or inject anything into your veins.
MRI uses radio waves and powerful magnets, instead of x-rays as in a CT scan, to view internal structures and organs. The waves are absorbed by the body and then released. A computer translates the patterns formed by this energy release into detailed images of areas inside the body. MRI produces cross-sectional slices like a CT scanner, but also produces slices that are parallel to the length of the body. There are many good reasons that people get CT scans. They are used by doctors to obtain additional information when initial symptoms or screening indicate that there could be a problem within the body. They are also used by individuals interested in taking preventive measures to avoid health problems by having their bodies checked out.
An MRI uses a strong magnetic field, radio waves, and a computer to generate detailed images of the body without the use of radiation. These images allow radiologists to diagnose many pathologic processes. MRI is widely used for imaging soft tissues in the body including the brain, nerves and muscles.
Magnetic Resonance Cholangiopancreatography (MRCP)
Magnetic Resonance Cholangiopancreatography (MRCP) is a type of MRI and is an alternative to ERCP. It is safer and faster than ERCP, because it is non-invasive and no dye is used. MRCP is used to view the pancreatic and bile ducts, which are difficult to see with CT or MRI.
Ultrasonography is another imaging test that is commonly used and many people are familiar with it. These scans are also referred to as ultrasounds, sonograms or ultrasonograms. During this test, a transducer or wand-shape device is placed against the area being examined. The high frequency sound waves produce echoes that are converted into electrical signals to create precise images of the body.
Unlike x-rays an ultrasound does not use radiation; therefore it is considered a safe alternative for imaging pregnant women.
Positron Emission Tomography (PET scanner)
Positron Emission Tomography, or PET scan, is an imaging test that shows anatomy and
biological function. During a PET scan, a small amount of radioactive glucose (sugar) is injected into a vein. Then a special camera detects the radioactivity that is taken up by cancer tissue.
PET scans are increasingly read alongside CT or (MRI) scans, the combination ("coregistration") giving both anatomic and metabolic information (i.e., what the structure is, and what it is doing biochemically).
Endoscopic Retrograde Cholangiopancreatography (ERCP)
Endoscopic Retrograde Cholangiopancreatography, or ERCP, is an invasive procedure that is used with a dye to view the bile and pancreatic ducts for any blockages. During an ERCP, you receive an anaesthetic to numb your throat and medication to make you sleepy. A thin tube is passed down your throat, through your stomach, and into your small intestine.
ERCP is especially helpful for patients with jaundice because a stent can be inserted and left in place to keep ducts open, often relieving the jaundice and its associated symptoms. In addition, during the ERCP doctors can collect small particles of any tumours there may be, to be analyzed under the
Because the only definitive way to diagnose cancer is to directly visualize cancer cells under a microscope, a biopsy may be performed when pancreatic cancer is suspected. A biopsy is the process of removing tissue samples, which are then examined under a microscope to check for cancer cells (Figure 10) Fine-needle aspiration (FNA) is a technique in which cells are aspirated from a tumour using a needle and syringe with the application of negative pressure. The technique can be performed using image-directed guidance (Endoscopic Ultrasound-guided, CT guided) and is particularly helpful in the diagnosis of relatively inaccessible tumours.
Cancer is then diagnosed if there is evidence of distinct, abnormal growth of cells.
There is some controversy regarding the use of biopsy tissue diagnosis of pancreatic cancer before performing surgery on a suspected tumour. Some centres advocate the practice of operating on all patients thought to have early pancreatic cancer and argue against a preoperative biopsy tissue diagnosis. The concern is that false negative biopsy results can occur due a sampling error which could
influence the decision to proceed with surgical removal of the tumour.
Some surgeons are hesitant to perform an operation on patients without a positive tissue diagnosis to confirm pancreatic cancer. Tissue diagnosis is almost always required prior to initiation of chemotherapy, radiation therapy or the use of permanent metallic stents for relief in obstructive jaundice.
It is also possible that biopsy of the pancreas might spread cancer cells into the abdomen. Studies of the risk of spreading cancer with CT-guided biopsy have suggested that this risk is actually very low.
Unfortunately at this moment we don’t have a single blood test that can be used to make a diagnosis of pancreatic cancer.
Different tumour markers in the blood are used to detect and monitor many types of cancer. Tumour markers are substances produced by some tumour cells. There are two commercially available tumour marker tests are of use in patients with pancreatic cancer: cancer antigen 19-9(CA19-9) and carcinoembryonic antigen (CEA). These markers are not accurate enough to be used to screen healthy people for or to make a diagnosis of pancreatic cancer. However, CA19-9 and CEA are frequently used to track the progress of treatment in patients with pancreatic cancer.