How Pancreatic Cancer Is Diagnosed

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pancreatic cancer diagnosis
© Verywell, 2018

There are several pieces of information doctors look at in order to diagnose pancreatic cancer. Imaging tests may include a special type of abdominal CT scan, endoscopic ultrasound, MRI, or ERCP.  Blood tests can look for causes of jaundice as well as tumor markers. And a medical history focusing on risk factors, along with a physical exam, are important.

A biopsy may or may not be needed, depending on other findings. After diagnosis, staging is done to determine the most appropriate treatments for the disease.

Everyone should be aware of the potential warning signs and symptoms of pancreatic cancer, so they can seek a medical evaluation as early as possible.

Labs and Tests

The evaluation for a possible pancreatic cancer usually begins with a careful history and physical exam. Your doctor will ask you questions about any risk factors you may have, including a family history of the disease, and will inquire about your symptoms. She will then perform a physical examination looking at your skin and eyes for evidence of jaundice; examining your abdomen for a possible mass or enlargement of your liver, or any evidence of ascites (build-up of fluid in the abdomen), and checking your records to see if you have lost weight.

Blood test abnormalities with pancreatic cancer are fairly non-specific but are sometimes helpful in making a diagnosis when combined with imaging tests.

 Tests may include:

  • Liver function tests, which are sometimes increased
  • A complete blood count (CBC), looking for an elevated platelet count (thrombocytosis) in particular
  • A bilirubin test: There are different types of bilirubin, and based on the specific type tested, physicians may gain clues as to the source of any jaundice you have. With obstructive jaundice (due to a pancreatic tumor pushing on the common bile duct), there are elevations in both conjugated and total bilirubin.

    Blood sugar is often elevated, as around 80 percent of people with pancreatic cancer will develop insulin resistance or diabetes. Around half of people have elevations in serum amylase and serum lipase in the early stages of the disease, but less so in advanced disease.

    Tumor Markers

    Tumor markers are proteins secreted by cancer cells and can be detected via a blood test. One of these markers, carcinoembryonic antigen (CEA), is elevated in roughly half of the people diagnosed with the disease but is also elevated in several other types of conditions as well. CA 19-9 levels may be tested, but since they are not always elevated and raised levels can also indicate other medical conditions, this is not particularly helpful in making a diagnosis of pancreatic cancer. This result, however, is helpful in deciding if a pancreatic tumor can be removed surgically, and for following the course of treatment.

    Neuroendocrine Tumor Blood Tests

    Certain blood tests may also be helpful in diagnosing the rare type of pancreatic cancers referred to as neuroendocrine tumors. Unlike most pancreatic tumors, that are composed of cells that make digestive enzymes, these tumors involve endocrine cells that make hormones such as insulin, glucagon, and somatostatin.

    Measuring levels of these hormones, as well as conducting a few other blood tests, can be helpful in diagnosing these tumors.

    Imaging

    Imaging tests are usually the primary method of confirming or refuting the presence of a mass in the pancreas. Options may include:

    CT Scan

    Computerized tomography (CT) uses X-rays to create a cross-section of a region of the body and is often the mainstay of diagnosis. If a physician suspects pancreatic cancer specifically, a special type of CT scan called a multiphase helical CT scan or pancreatic protocol CT scan is often recommended.

    A CT scan can be helpful both for characterizing the tumor (determining its size and location in the pancreas) and looking for any evidence of spread to lymph nodes or other regions.

    CT may be more effective than endoscopic ultrasound in determining whether cancer has spread to the superior mesenteric artery (important in choosing treatment).

    Endoscopic Ultrasound (EUS)

    Ultrasound uses sound waves to create an image of the inside of the body. A conventional (transcutaneous) ultrasound is not usually done if a doctor suspects pancreatic cancer, as intestinal gas can make visualization of the pancreas difficult. But it may be helpful when looking for other abdominal problems.

    An endoscopic ultrasound can be a valuable procedure in making the diagnosis. Done via endoscopy, a flexible tube with an ultrasound probe at its end is inserted through the mouth and threaded down into the stomach or small intestine, so that the scan can be done from inside. Since these areas are very near to the pancreas, the test allows doctors to get a very good look at the organ.

    With the use of medications (conscious sedation), people usually tolerate the procedure well. The test may be more accurate than CT for assessing the size and extent of a tumor but isn't as good at finding any distant spread of the tumor (metastases) or determining if the tumor involves blood vessels.

    Endoscopic Retrograde Cholangiopancreatography (ERCP)

    Endoscopic retrograde cholangiopancreatography (ERCP) is a test that involves endoscopy plus X-rays in order to visualize the bile ducts. ERCP can be a sensitive test for finding pancreatic cancer but is not as accurate in differentiating the disease from other problems, such as pancreatitis. It's also a more invasive procedure relative to the tests above.

    MRI

    Magnetic resonance imaging (MRI) uses magnets rather than X-rays to create an image of internal structures. MRI is used less often than CT with pancreatic cancer but may be used in certain circumstances. As with CT, there are special types of MRI, including MR cholangiopancreatography (MRCP). Since it hasn't been studied as much as the tests above, it's used primarily for people for whose diagnosis is unclear based on other studies, or if a person has an allergy to the contrast dye used for CT.        

    Octreoscan

    A test called an octreoscan or somatostatin receptor scintigraphy (SRC) may be done if a neuroendocrine tumor of the pancreas is suspected. In an octreoscan, a radioactive protein (called a tracer) is injected into a vein. If a neuroendocrine tumor is present, the tracer will bind to cells in the tumor. Several hours later, a scan (scintigraphy) is done that picks up any radiation that is being emitted (neuroendocrine tumors will light up, if present).

    PET Scan

    PET scans, often combined with CT (PET/CT), may occasionally be done, but are used much less often with pancreatic cancer than with some other cancers. In this test, a small amount of radioactive sugar is injected into a vein and a scan is done after the sugar has had time to be absorbed by cells. Actively growing cells, such as cancer cells, will "light up," in contrast to areas of normal cells or scar tissue.

    Biopsy

    A sample of tissue (a biopsy) is sometimes needed to confirm the diagnosis, as well as look at the molecular characteristics of the tumor.

    A fine needle biopsy (a procedure in which a thin needle is directed through the skin in the abdomen and into the pancreas to extract a sample of tissue) is most often done using guidance with either ultrasound or CT. There is some concern that this type of biopsy could "seed" the tumor, or result in the spread of the cancer along the line where the needle is introduced. It's not known how often seeding occurs, but according to a 2017 study, the number of case reports of seeding due to endoscopic ultrasound-guided fine needle aspiration has been rapidly increasing.

    Since biopsies are done primarily to see if surgery may be done (the only treatment that improves long-term survival), this is a concern worth talking about with your doctor.

    As an alternative approach, laparoscopy may be used, especially if a tumor may be able to be removed (resectable). In a laparoscopy, several small incisions are made in the abdomen and a narrow instrument is inserted to perform the biopsy. Since, around 20 percent of the time, people are found to have inoperable disease after surgery has already begun for pancreatic cancer, some physicians recommend doing this test for anyone who will be having surgery (to avoid unnecessary extensive surgery).

    Differential Diagnoses

    There are a number of conditions that may mimic the symptoms of pancreatic cancer or result in similar findings on blood tests and imaging. Doctors will work to rule out the following before making a diagnosis:

    • Bile duct stricture: A bile duct stricture is an abnormal narrowing of the bile duct. It may be caused by gallstones or surgery to remove them, but may also be caused by pancreatic cancer.
    • Acute or chronic pancreatitis: Pancreatitis, an inflammation of the pancreas, can cause similar symptoms, but does not result in a mass. In around 1 in 20 people, acute pancreatitis is present at the time of diagnosis of pancreatic cancer.
    • Bile duct stones: Stones in the bile duct can cause symptoms of obstructive jaundice and can often be seen on ultrasound. Like bile duct strictures, however, they may be present along with pancreatic cancer.
    • Ampullary carcinoma
    • Gallbladder cancer: Gallbladder cancers can appear very similar to pancreatic cancers, but may be differentiated with CT or MRI.
    • Gallstones (cholelithiasis)
    • Gastric or duodenal ulcers
    • Abdominal aortic aneurysm 
    • Pancreatic lymphoma
    • Gastric lymphoma
    • Liver cancer
    • Bile duct cancer 

    Staging

    Determining the stage of a pancreatic cancer is extremely important when it comes to deciding whether a cancer can be surgically removed or not. If staging is inaccurate, it may lead to unnecessary surgery. Staging can also assist in estimating the prognosis of the disease.

    TNM Staging

    Doctors use a system called TNM staging to determine the stage of a tumor. This can be terribly confusing at first but is much easier to understand if you know what these letters mean.

    T stands for tumor. A tumor is given a number from T1 to T4 based on the size of the tumor, as well as other structures the tumor may have invaded.

    Primary Tumor
     T1 Tumor confined to the pancreas and less than 2 cm
     T2 Tumor confined to the pancreas and more than 2 cm
     T3  Tumor extends beyond the pancreas (to the duodenum, bile duct, portal or mesenteric vein), but does not involve the celiac axis or superior mesenteric artery
     T4 Tumor involves the celiac artery or the superior mesenteric artery

     

    N stands for lymph nodes. N0 would mean that a tumor has not spread to any lymph nodes. N1 means that the tumor has spread to nearby lymph nodes.

    Lymph Node Involvement
     N0 No involvement of regional lymph nodes
     N1 Regional lymph nodes are positive for cancer


    M stands for metastases. If a tumor has not spread, it would be described as M0. If it has spread to distant regions (beyond the pancreas) it would be referred to as M1.

    Distant Metastasis (Spread) of the Cancer
     M0 No distant metastasis
     M1 Distant metastasis

    Based on TNM, tumors are then given a stage between 0 and 4. There are also substages.

    Stage 0: Stage 0 is also referred to as carcinoma in situ and refers to cancer that has not yet spread past something called the basement membrane. These tumors are not invasive (though subsequent stages are) and should theoretically be completely curable.

    Stage 1: Stage 1 (T1 or T2, N0, M0) pancreatic cancers are confined to the pancreas and are less than 4 cm (about 2 inches) in diameter.

    Stage 2: Stage 2 tumors (either T3, N0, M0 or T1-3, N1, M0) either extend beyond the pancreas (without involving the celiac axis or superior mesenteric artery) and have not spread to lymph nodes, or are confined to the pancreas but have spread to lymph nodes. 

    Stage 3: Stage 3 tumors (T4, any N, M0) extend beyond the pancreas and involve either the celiac artery or superior mesenteric artery. They may or may not have spread to lymph nodes, but have not spread to distant regions of the body.

    Stage 4: Stage 4 tumors (Any T, any N, M1) can be any size. While they may or may not have spread to lymph nodes, they have spread to distant sites such as the liver, the peritoneum (the membranes that line the abdominal cavity), the bones, or the lungs.

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