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Endoscopic Ultrasound in the Diagnosis and Staging of Pancreatic Cancer

Endoscopic Ultrasound in the Diagnosis and Staging of Pancreatic Cancer

Two decades have elapsed since publication of the first
papers describing the examination of the pancreas via the stomach and the
duodenum using an ultrasound probe fixed to an endoscope tip. Initial attempts
to image the pancreas in this fashion proved difficult and frustrating, but they
were promising enough that instrument makers and gastrointestinal endoscopists
persisted in developing increasingly effective devices.

Called "a marriage of inconvenience" in a 1987 editorial in the
Lancet
,[1] endoscopic ultrasonography is now available in most academic medical
centers and in many large community hospitals. The 13th International Symposium
on Endoscopic Ultrasonography, to be held October 4-6, 2002, in New York
City, will devote a major forum to issues involving the imaging of pancreatic
neoplasms.

Endoscopic Ultrasound and the Pancreas

Endoscopic ultrasound has proved to be a good marriage after all. It is an
accurate method for locoregional staging of gastrointestinal neoplasms and for
evaluation of extrinsic mass lesions close to the gastrointestinal tract. The
entire pancreas, including the uncinate process, head, body, and tail, can
usually be scanned through the stomach and the duodenum. Because the transducer
is close to the pancreas, interference from the abdominal wall and bowel gas is
eliminated. Higher-frequency ultrasound with shorter penetration can be used,
producing images with greater clarity and detail. The development of endoscopic
ultrasound-guided fine-needle aspiration (FNA) of the pancreas has provided a
new means by which to obtain cytologic material and tumor markers and to improve
diagnostic yield and accuracy.

Drs. Levy and Wiersema have written a superb review of the current experience
and evidence supporting the use of endoscopic ultrasound in the diagnosis and
staging of pancreatic cancer. They present extensive data indicating that the
technique is very accurate for the detection of pancreatic masses, identifying
more than 90% of them. The negative predictive value is in the same range, so
that a negative endoscopic ultrasound examination of the pancreas is very
helpful when body imaging with computed tomography (CT) or magnetic resonance
imaging (MRI) is equivocal. The authors also provide recent evidence that
endoscopic ultrasound remains helpful in detecting or ruling out pancreatic
masses even with the improvements in helical CT scanners and MRI technology.

Guiding Management Decisions

A persistent problem for endoscopic ultrasound imaging is the difficulty in
differentiating a neoplastic mass in the pancreas from focal pancreatitis. The
difficulty is compounded because chronic pancreatitis increases the risk of
developing carcinoma of the pancreas, and because pancreatic cancers often
create a surrounding inflammatory and desmoplastic reaction. Fine-needle
aspiration using endoscopic ultrasound guidance has been a major advance in
helping to solve this dilemma. While a negative cytology does not rule out the
possibility of a malignancy, a positive cytology is highly specific and can help
guide a patient to surgical or combined-modality therapies.

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