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Blood tests for pancreatic cancer
Laboratory values can indicate pancreatic cancer, but they are not specific or sensitive for cancer of the pancreas.
A laboratory blood test known as carbohydrate antigen 19-9 (CA 19-9) is also used in the diagnosis of pancreatic cancer.
- The normal range of CA 19-9 is between 0 and 37 U/mL, but people with pancreatic cancer often have higher levels.
- As cancer progresses, CA 19-9 levels go on increasing.
- Doctors may also use CA 19-9 levels to monitor the response of pancreatic cancer to cancer therapy.
- However, an elevated CA 19-9 level does not always indicate pancreatic cancer. It may also be found in
- Noncancerous conditions such as pancreatitis, liver cirrhosis and noncancerous blockage of the common bile duct may also increase the CA 19-9 level.
Levels of pancreatic enzymes such as serum amylase and serum lipase in blood may also be found elevated in pancreatic cancer. However, these can also be found in noncancerous pancreatic diseases. Doctors may order liver function tests to check bilirubin levels and liver functions. Elevated bilirubin levels may indicate blockage of the common bile duct caused by pancreatic cancer. Moreover, these may be found in other conditions such as gallbladder stones and a viral infection called mononucleosis.
What are other tests used in the diagnosis of pancreatic cancer?
Doctors will look for signs and symptoms that indicate pancreatic cancer. They will look for signs of jaundice that include the yellowish color of the eyes and skin. They will take the patient’s complete medical history and family history to look for possible risk factors such as smoking. They will examine the patient’s abdomen to check if there is swelling of the liver or gallbladder.
If doctors suspect some abnormality, they will order the following tests.
- Ultrasound (US): Ultrasound, particularly an abdominal ultrasound, is a simple test that does not use radiation but sound waves to diagnose tissue abnormalities. It is often the first test used to look at the organs for complaints such as abdominal pain. It may not give a final diagnosis.
- The endoscopic ultrasound (EUS) test is more accurate than the abdominal US. For the EUS test, doctors insert a small US probe on the tip of a thin, flexible tube through a small incision into the abdomen to look for signs of pancreatic cancer. They may also remove a small piece of the tumor (biopsy) and send it to the laboratory to check for the cancerous cells.
- Computed tomography (CT) scan: A CT scan is often used as the primary test to diagnose or confirm pancreatic cancer. It can show the pancreas and tumor fairly clearly. It also helps doctors know how extensively cancer has spread in the pancreas. A special type of CT known as a multiphase CT scan or pancreatic protocol CT scan is used in which doctors administer a special substance known as an intravenous (IV) contrast. This helps highlight problematic areas in the pancreas.
- Doctors may insert a long needle into the pancreas to take a small piece of the pancreas. During this procedure, they use a CT scan to guide the needle. They then send the sample of the pancreas to the laboratory for examination under a microscope. This procedure is known as CT-guided biopsy.
- Cholangiopancreatography: This procedure helps doctors check if there is any blockage, narrowing, or dilation in the pancreatic and bile ducts. A type of this procedure known as endoscopic retrograde cholangiopancreatography (ERCP) involves putting a thin, lighted tube called an endoscope through the mouth and stomach into the small intestine. This is followed by passing a smaller tube called a catheter through the endoscope and into the bile and pancreatic ducts. A dye is injected into the ducts that can highlight the cancerous portions in the pancreas.
- Magnetic resonance imaging (MRI): Special types of MRI scans, namely, MR cholangiopancreatography (MRCP), can be used to look at the pancreatic and bile ducts. Doctors usually prefer MRCP to ERCP to diagnose pancreatic cancer and distinguish pancreatitis from pancreatic cancer.
- Angiography: It is a procedure in which doctors inject a dye into an artery leading to the pancreas. This highlights any problems in the blood vessels around the pancreas and shows them up on an X-ray.
- Biopsy: A biopsy involves removing a piece of a pancreatic tumor and sending it to the laboratory to examine it under a microscope. It is the most reliable test to diagnose pancreatic cancer.