Tests for Pancreatic Cancer
If your doctor suspects pancreatic cancer, you may have one or more of the following
tests to diagnose the cancer:
Transabdominal ultrasonography is the most sensitive test for detecting
gallstones, an ever-present issue in the elderly patient who is jaundiced. Ultrasonography
can demonstrate dilated intrahepatic and extrahepatic bile ducts, liver metastases,
pancreatic masses, ascites, and enlarged peripancreatic lymph nodes. Pancreatic
cancer typically appears as a hypoechoic mass on ultrasonography. Ultrasonography
will reveal a pancreatic mass in 60 to 70 percent of patients with cancer. Because
helical CT is just as sensitive as ultrasonography and provides more complete information
about surrounding structures and the local and distant extent of the disease, ultrasonography
has been largely replaced by CT.
Computerized tomography (CT) scan – a CT scan uses an X-ray that
is linked to a computer to take a series of detailed pictures that will help your
doctor see your internal organs. The CT machine has a large hole, and you will lie
on a bed that passes through this hole. As you move through the hole, the CT takes
several X-rays. In some cases, you may receive an injection of dye into a vein in
your arm to help highlight the areas your doctor wants to see. The most sensitive
way to diagnosis a pancreatic cancer by CT is to ensure that a High-Quality
Three-Phase CT with Pancreatic Protocol is performed. Other types
of CT are not as sensitive and may miss a mass, lesion, tumor or cancer. Helical
or spiral CT is the preferred noninvasive imaging test for the diagnosis of pancreatic
cancer. Pancreatic cancer usually appears as an area of pancreatic enlargement with
a localized hypodense lesion. In addition to determining the primary tumor size,
CT is used to evaluate invasion into local structures or metastatic disease.
Magnetic resonance imaging (MRI) – MRI uses a strong magnetic field
and radio waves to create images of your pancreas. In general, MRI offers no significant
advantages over CT because of a low signal-to-noise ratio, motion artifacts, lack
of bowel opacification, and low spatial resolution. More recently, however, the
introduction of magnetic resonance cholangiopancreatography (MRCP) has offered a
promising noninvasive technique that can visualize both the bile duct and the pancreatic
duct; images are similar to those obtained with ERCP.
Endoscopic retrograde cholangiopancreatography (ERCP) -- ERCP uses
a dye to highlight the bile ducts in your pancreas. During ERCP, your doctor gently
passes an endoscope, which is a thin, flexible tube, down your throat through your
stomach and into the upper part of your small intestine. Air is used to inflate
your intestinal tract so your doctor can more easily see the openings of your pancreatic
and bile ducts. Your doctor then injects a dye into the ducts through a catheter
that is passed through the endoscope. Finally, X-rays are taken of the ducts. The
X-rays can show whether the ducts are narrowed or blocked by a tumor or anything
else. The sensitivity of ERCP for the diagnosis of pancreatic cancer approaches
90%. The finding of a long, irregular stricture in an otherwise normal pancreatic
duct is highly suggestive of a pancreatic cancer. Often, the pancreatic duct will
be obstructed with no distal filling. Although ERCP is reliable in confirming the
presence of a clinically suspected pancreatic cancer, it should not be used routinely.
Diagnostic ERCP should be reserved for patients with presumed pancreatic cancer
and obstructive jaundice in whom no mass is demonstrated on CT, symptomatic but
nonjaundiced patients without an obvious pancreatic mass, and patients with chronic
pancreatitis in whom the development of a pancreatic mass is suspected based on
clinical evidence or the development of jaundice.
Percutaneous transhepatic cholangiography (PTC) -- Your doctor
inserts a thin needle into your liver and injects the dye into your liver to highlight
your bile ducts. A fluoroscope, which is a special X-ray machine, tracks the dye
as it moves through the ducts. Unless there is a blockage, the dye should move freely
through the bile ducts.
Biopsy – During a biopsy, your doctor removes a small sample of
tissue from the pancreas to examine under a microscope to look for cancer cells.
Your doctor can obtain a sample by inserting a needle through your skin into your
pancreas. This is called fine-needle aspiration. Your doctor also can get a sample
using endoscopic ultrasound to guide special tools into your pancreas where a sample
of cells can be obtained for testing. However, you do not have to have a biopsy
to prove pancreatic cancer. Any patient over the age of 45 who presents jaundice,
with a mass in the head of the pancreas has a pancreatic cancer in greater than
95% of the time. Delaying treatment options to obtain a biopsy is not warranted.
Staging Pancreatic Cancer