Do Blood Tests Show Pancreatic Cancer?

Medically Reviewed on 4/27/2021
cancer blood test
Blood tests are often used in combination with other tests to detect pancreatic cancer

At present, there is no single screening test that can identify or provide an early diagnosis of pancreatic cancer. Blood tests are therefore often used in combination with other clinical assessments and tests to diagnose pancreatic cancer.

Certain substances in the blood, called tumor markers, may be elevated in people with pancreatic cancer. Your doctor may use blood samples to check the levels of these tumor markers, such as carcinoembryonic antigen (CEA) and cancer antigen 19-9 (CA 19-9). High levels of tumor markers may indicate the presence of pancreatic cancer. Tumor marker levels can be also used to monitor the response to cancer treatment. 

Jaundice often occurs in patients with pancreatic cancer. Because of this, your doctor may take blood samples and examine them for levels of substances that indicate how well the liver is functioning (such as bilirubin) or whether other organs are affected by a pancreatic tumor. 

Unfortunately, pancreatic cancer does not show any changes in blood samples in the early stages. Your doctor may therefore recommend other tests along with blood tests to confirm pancreatic cancer.

What other tests are used to diagnose pancreatic cancer?

Computed tomography (CT) scan

  • An X-ray machine linked to a computer takes a series of detailed pictures of the pancreas, nearby organs and blood vessels in the abdomen.
  • The patient may receive an injection of contrast material so that the pancreas shows up clearly in the pictures.
  • On the CT scan, the doctor may see a tumor in the pancreas or elsewhere in the abdomen.

Ultrasound

  • The doctor places the ultrasound probe on the abdomen and slowly moves it around.
  • The ultrasound device uses sound waves to make a pattern of echoes as they bounce off internal organs.
  • The echoes create a picture of the pancreas and other organs in the abdomen. The picture may show a tumor or blocked ducts.

Endoscopic ultrasound (EUS)

  • The doctor passes a thin, lighted tube (endoscope) down the throat, through the stomach and into the first part of the small intestine.
  • An ultrasound probe at the end of the tube sends out sound waves. The waves bounce off tissues in the pancreas and other organs.
  • As the doctor slowly withdraws the probe from the intestine toward the stomach, the computer creates a picture of the pancreas from the echoes.
  • The picture can show a tumor in the pancreas. It can also show how deeply cancer has invaded the blood vessels.

Endoscopic retrograde cholangiopancreatography (ERCP)

  • A special endoscope is inserted through the mouth and directed to the first part of the small intestine.
  • A smaller tube is then inserted through the endoscope into the bile ducts.
  • A dye is injected through the tube, and an X-ray is taken.
  • If cancer is suspected, a small piece of tissue can be taken for biopsy.
  • If the ducts are blocked by a tumor, a stent may be inserted to relieve blockage.
  • This may help alleviate stomach pain and digestive problems.

Magnetic resonance imaging (MRI)

  • A large machine with a strong magnet linked to a computer is used to make detailed pictures of areas inside the body.

Positron emission tomography (PET) scan

  • Patients receive an injection of a small amount of radioactive sugar. The radioactive sugar gives off signals that the PET scanner picks up.
  • The PET scanner takes pictures of the places in the body where the sugar is being absorbed.
  • Cancer cells show up brighter in the picture because they absorb sugar faster than normal cells. A PET scan may show a tumor in the pancreas.
  • A PET scan can also show cancer that has spread to other parts of the body.

Needle biopsy

  • The doctor uses a thin needle to remove a small sample of tissue from the pancreas. EUS or CT may be used to guide the needle.
  • A pathologist uses a microscope to look for cancer cells in the tissue.

Certain academic institutions are conducting studies to establish protocols involving periodic testing procedures to monitor people at high risk for pancreatic cancer, but these measures have not been thoroughly studied yet.

The best blood marker to detect pancreatic cancer is CA 19-9, which is a “carbohydrate-associated antigen” also known as a sialyl Lewis (a) antigen. This marker is somewhat uneven in the diagnosis of pancreatic cancer but can be quite elevated in those with the disease. Some oncologists feel that the CA 19-9 marker can be used as a guide to monitor the disease and treatment process in a patient. Many other agents have been studied as screening and diagnostic markers without much success. 

However, research regarding screening methods for the early diagnosis of pancreatic cancer has increased dramatically in the past decade.

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Medically Reviewed on 4/27/2021
References
WebMD. Pancreatic Cancer Diagnosis and Early Detection. https://www.webmd.com/cancer/pancreatic-cancer/pancreatic-cancer-diagnosis