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hot stone embedded in the middle of my belly. That’s what the
nagging ache felt like when it asserted itself abruptly one evening—a
distinctive new addition to the repertoire of usual gastric phenomena
I’d experienced over decades of stomach ownership. Like anyone
else’s,
at one time or another the old tummy has felt queasy, nauseated, acidic,
cramped, gassy, growlingly empty, pleasantly full, and Thanksgivingly
overstuffed. But not until that particular evening had it felt hot-stone-achy.
This worrisome ache—along with volcanic belching—waxed and
waned over a few weeks.
When it finally became too intense, I visited my primary-care physician.
He put me on a blessedly effective acid reducer that seemed to give
relief, and he referred me to a Duke gastroenterologist. A subsequent
test showing a faint sign of blood in a stool sample prompted her
to order the Full Monty of tests on my middle-aged, and therefore
suspect, gastrointestinal system. The resulting medical odyssey led
me through three of Duke’s GI diagnostic labs, where, fortunately,
the kind ministrations of some very sympathetic professionals made
the experience about as pleasant as such procedures can probably be.
In the upper GI lab, I gulped chalky liquid to
make my stomach opaque to X-rays and swallowed fizzy crystals to inflate
it. Barely holding back the mother of all belches, I watched with
utter fascination the sloshings of my honest-to-God actual stomach
on the video screen—for the first time really witnessing that
heretofore invisible, and sometimes rebellious, pouch. The jovial
technician and I also discussed my intestines. She volunteered that
she’d seen lots of intestines in her time, and not one set looked
like the neat assemblage portrayed in textbooks. She’d seen intestinal
kinks, loops, knots, and all manner of other unruly arrangements.
A visit to the ultrasound lab brought me to another nice technician,
who showed me the shadowy outlines of my gallbladder and pancreas.
We were both gratified to find them in their place—although I
recall with some chagrin that my liver was pronounced slightly fatty.
A week or so later came the piéce
de résistance—the colonoscopy. The day before, I had undergone
the rigors of overnight fasting, of drinking only clear liquids, and
of ingesting a thoroughly pipe-clearing physic. That morning found
me lying woozily on a table in the colonoscopy lab watching on a video
monitor a Fantastic Voyage through my glistening, beige nether passage.
As I waited for the final report on the various explorations of my
internal labyrinth, I launched an exploration of my own into the impressive
array of other diagnostic and treatment techniques that Duke gastroenterologists
employ to understand and cure GI disorders. Such a broad capability
is one reason the gastroenterology division has been ranked among
the best in the country.
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| McGrath and
endoscope: examining via EUS (endoscopic ultrasound) |
Gastroenterologists can diagnose and treat the
rising tide of GI disorders using ever more effective and benign tools,
including ultrasound endoscopes that can explore the GI tract from
the inside, “photodynamic therapy” techniques that use laser
light to activate chemicals that selectively destroy dysplastic cells
in the esophagus, and computer-generated X-ray images, called “virtual
colonoscopies,” of the intestine.
Of these, perhaps the most revolutionary-sounding is the virtual colonoscopy,
which theoretically enables radiologists to explore a colon for cancers,
polyps, and other pathologies without using an invasive probe. The
technique involves performing an X-ray CT scan of the abdomen and
pelvis and using a computer to analyze the X-ray data to reconstruct
the interior topography of the colon. A new technology is not necessarily
a better technology. So, associate professor Don Rockey and his colleagues
are leading a $7-million study to compare the accuracy of virtual
colonoscopy with the venerable barium enema X-ray and the colonoscopy.
“We’re comparing the three techniques to find which one
reveals such abnormalities as cancers, polyps, colitis, and inflammation,”
says Rockey, who heads the gastroenterology division’s Liver
Center. “And, we’re also asking patients for their opinions
on comfort, pain, and the likelihood that they would be willing to
repeat the procedure.” After all, adds Rockey, even the most
effective diagnostic technique is useless unless patients are willing
to undergo it.
As a radiologist, associate professor Erik Paulson M.D. ’85,
who is also participating in the trial, agrees with the need for patient
cooperation. He and his fellow radiologists are only too aware of
the problems of persuading patients to undergo the colonoscopy screening
that could save their lives. Says Paulson, “We know that if we
can catch colon polyps early and remove them, we can greatly reduce
or eliminate colon cancer. But despite the fact that screening works,
lots of patients don’t get screened. Either their family doctor
or internist doesn’t recommend it, or they don’t want to
because of the discomfort.” Thus, says Paulson, virtual colonoscopy—more
correctly called “CT colonography”—seems to offer a
way to screen patients that is not, literally, a pain in the butt.
Despite the technique’s patient-friendliness, CT colonography
might not become widespread because of its complexity, says Paulson.
“While there are many well-trained gastroenterologists and radiologists,
we need to make sure that they can routinely interpret the results
from CT colonography accurately. There may not be that many medical
centers like Duke, in which gastroenterologists and radiologists work
together so effectively.”
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| Baillie uses
ECRP optics for noninvasive surgery on bile ducts |
While the clinical trial—funded by the National
Cancer Institute through the Duke Comprehensive Cancer Center—is
only in the first of its four years, Rockey suspects that the results
will not be a slam-dunk for any of the techniques. “Colonoscopy
is probably the most accurate test compared to the X-ray methods,
but the question is whether the X-ray tests are still accurate enough
to make them useful. The fact is that there are simply not enough
people to perform colonoscopies on patients with colon abnormalities,”
he says. “Also, colonoscopies are very expensive, especially
compared with barium enema X-rays, and there is a small but significant
risk of complications such as perforation of the intestine. So, I
suspect that the three will be complementary in many respects, and
I would be very surprised if any of them becomes the exclusive method
of choice.”
Another exotic-sounding visualization technique being advanced by
the Duke gastroenterologists is “endoscopic ultrasound”
(EUS). Most ultrasound examinations, such as the one that revealed
my gallbladder in all its glory, are conducted from the outside, with
the same type of ultrasound probe used to see a future-junior in a
pregnant mom’s belly. However, EUS sees from the inside. Basically,
the technique involves threading an endoscope, whose tip holds an
ultrasound transducer, either through the throat or rectum. Physicians
can, thus, obtain an up-close sonar image of the GI tract that provides
far better resolution. Says assistant professor Kevin McGrath, who
participates in the division’s EUS research and applications,
“We use EUS mainly for determining the stage of cancers, including
esophageal, gastric, pancreatic, and rectal.”
Determining a cancer’s stage of progression is a key to guiding
treatment. In particular, the fact that ultrasound penetrates tissue
means that physicians can also use it to evaluate abnormalities immediately
adjacent to the GI tract. The EUS system allows physicians to do more
than see a cancer, says McGrath; a needle aspirator allows the scientists
to use real-time ultrasound guidance to biopsy abnormal lymph nodes
around the stomach or pancreas or to sample any tissue that looks
abnormal on a previous endoscopy or CT scan. The system even has a
“Doppler” capability that allows physicians to detect flowing
blood, allowing them to avoid blood vessels and minimize the possibility
of bleeding from the biopsy.
GI BLUES
Gastroenterology is an especially vital medical
specialty these days because of an epidemic of GI disorders
in this country. According to government data, 100 million Americans
annually suffer digestive problems of some kind. These include
the common heartburn that pushes annual antacid sales well over
$100 million, and irritable bowel syndrome (IBS), which affects
between 25 and 55 million people in this country and causes
about 20 to 40 percent of all visits to gastroenterologists.
IBS is a chronic disorder of bowel motion and pain perception
that causes cramps and diarrhea. More serious, and even life-threatening,
is the immune-related inflammatory bowel disease (IBD), the
principal types being ulcerative colitis and Crohn’s disease,
which can cause severe digestive and nutritional problems.
Americans are also suffering an epidemic of the particularly
painful heartburn of gastroesophageal reflux disease, or GERD.
GERD results from the loss of tone in the lower esophageal sphincter—a
circular muscle that’s a one-way valve between the esophagus
and the stomach. GERD arises when part of the stomach pushes
through a hole in the diaphragm into the chest—a so-called
“hiatus hernia.” So, the nagging “heartburn”
behind the breastbone, and the sour taste of GERD, can be triggered
by any increased pressure on the stomach—caused by obesity,
tight clothing, straining to urinate or defecate, or coughing.
Aging baby-boomers are especially prone to GERD because our
lower esophageal sphincters weaken with age. For an unfortunate
700,000 people in this country, GERD develops into “Barrett’s
esophagus,” in which the cells lining the esophagus react
to chronic burning with stomach acid by transforming into cells
resembling those in the small intestine. This protective reaction
is perfectly understandable, given that stomach acid has the
same pH as car battery acid.
While GERD can be treated effectively with acid-suppressing
drugs, in some people these altered cells evolve into premalignant
cells, a process called dysplasia. While treatment can still
eliminate such dysplastic cells, they are likely the origin
of the vast majority of esophageal cancers.
The bottom line to all these scary statistics is that if you
experience digestive problems or chronic heartburn, run, don’t
walk, to your nearest gastroenterologist. |
According to associate professor Paul Jowell, who
directs the division’s EUS effort, “EUS has probably become
the most accurate technique for staging of tumors within the wall
of the GI tract.” However, he cautions, the new technique has
brought with it a demand for new skills and training. “It’s
a challenge to position the probe adequately, but even once you do
that there are pitfalls to interpreting the images accurately. So,
there is a significant learning curve to both the technique and the
interpretation.”
Jowell is leading a clinical trial in which the researchers are comparing
EUS and CT scans with subsequent needle biopsies for diagnosing pancreatic
cancers. “One problem with CT scans is that they require a reasonably
sized mass before you can see it and biopsy it,” he says. “EUS
seems to be able to detect smaller tumors. Also, with CT, there is
often first a diagnostic study and then
a second study for the biopsy. With EUS,
we normally do both at the same time.”
Technological advances will continue to improve EUS as a diagnostic
tool, says Jowell. These improvements include smaller, more maneuverable
endoscopes and a new instrument with forward-viewing optics, as opposed
to current instruments that allow visualization only at an angle.
He predicts that future EUS instruments will not only visualize tumors,
but also be used as a method for injecting chemotherapeutic drugs
or vaccines.
Gastroenterologists are already routinely using one endoscopic treatment
called “photodynamic therapy” (PDT) for abnormal GI tissues
and cancers. In PDT, a light-sensitive chemical is first injected
into the bloodstream. For a reason physicians still do not completely
understand, cancerous or dysplastic tissues tend to accumulate more
of the chemical than do normal tissues. The gastroenterologists next
insinuate a fiber-optic-equipped endoscope into the GI tract near
a tumor or such dysplastic tissue as found in Barrett’s esophagus.
Flashing a low-power laser through the optical fiber, they expose
the chemical to light, activating it to generate a highly reactive
form of oxygen, which triggers a toxic chain reaction in the tissue,
killing the tumor or dysplastic cells.
Such therapy has proven especially useful in treating Barrett’s
esophagus with high-grade dysplasia, says McGrath, and that’s
important to preventing cancer. “Barrett’s esophagus is
a known risk factor for esophageal cancer, which is probably increasing
faster than any other type of cancer,” he says. Particularly
worrisome, says associate professor Scott Brazer ’77, M.H.S.
’90, director of Duke’s PDT treatment and research program,
is that many people with Barrett’s don’t know it. “Many
who have heartburn symptoms alleviated with antacids may have Barrett’s.
And about a third of patients with the disorder have no symptoms,
perhaps because their esophageal tissues have become resistant to
the acid. So, there are a frightening number of patients out there
at risk for adenocarcinoma that don’t have any idea that they
have it.”
Brazer and McGrath are testing a new PDT technique for more effectively
treating advanced cases of near-cancerous dysplasia. The method involves
inflating a clear plastic balloon in the esophagus to flatten out
the hills and valleys in the overgrown tissue, allowing a more uniform
exposure to the laser light. The physicians have already completed
the treatment phase of the clinical trial and are observing the patients
to determine whether the “centering balloon”—invented
by endoscopic PDT pioneer Gene Overholt at the University of Tennessee—will
prove more effective at removing, or ablating, dysplastic tissue.
Such advances are making PDT an even better choice over surgery, says
McGrath. “Until now, treatment for high-grade dysplasia was often
surgical removal of the entire esophagus, which is a major surgical
procedure for patients. And because many of the patients were elderly,
there was a significant risk of complications and even death. I think
this trial will show that PDT is an effective treatment and will save
patients with high-grade dysplasia from esophagectomy. However, we
need to learn more about safety and other issues before we can say
whether it will be useful in patients with lower-grade Barrett’s.”
Among the most demanding of the gastroenterologists’ endoscopic
techniques is the one with the mouthfilling title “endoscopic
retrograde cholangiopancreatography” (ERCP)
—a division service directed by professor John Baillie and associate
director Malcolm Branch, who is an associate professor. This technique
with the huge title employs one of the tiniest endoscopic devices.
ERCP involves threading an endoscope down the throat, through the
stomach, and into the duodenum. Unlike other forward-looking endoscopes,
the ERCP optics aim sideways, and the physicians use the imaging to
seek out the “ampulla,” a tiny opening where the pancreatic
and bile ducts exit into the intestine. Once they find the ampulla,
the gastroenterologists thread a tiny catheter through it to inject
X-ray dye, or to use small baskets to snag bile duct stones, electrocautery
to open the duct, or cylindrical stents to prop the duct open.
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"There
are promising techniques that will allow us to progress from
what used to be 25 percent sensitivity for picking up cancer
to 70 to 80 percent."
JOHN BAILLIE
Associate director, ECRP |
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“For such procedures as retrieving bile duct
stones and relieving certain types of malignant obstructive jaundice,
ERCP is superior to surgery in its reduced complications and length
of hospital stay,” says Jowell, who participates in ERCP procedures.
“In general, it’s a one-day outpatient procedure.”
He emphasizes that considerable skill is needed to master the art
of threading the catheter into the ampulla in the confusing, turbulent
depths of the intestine. “It sounds so straightforward because
there’s this opening and you think you can just slide the catheter
in. But the ampulla is surrounded by a muscle that often makes it
difficult to thread the catheter into the duct. Once past that, there
are curves in the duct and the pancreatic duct is often no larger
than a pencil lead.”
In fact, a study of fellows in training at Duke by Baillie, Jowell,
and their colleagues revealed that ERCP training elsewhere is often
inadequate. “The study showed that, to gain minimum competence
in ERCP, a physician must do from a 180 to 200 procedures. But the
average training number we found in most fellowships was twenty-five
to fifty. We came in for a lot of heat about the study, but our data
were indisputable,” says Baillie, who was awarded the 2001 “Master
Endoscopist Award” by the American Society for Gastrointestinal
Endoscopy.
Many surgeons were initially resistant to ERCP, but most medical centers
have now developed the same kind of productive partnership between
gastroenterologists and surgeons that Duke enjoys. Baillie says, “There
are surgeons depending on me and my team for what we do, and vice
versa. Most diseases involving the liver, bile ducts, and pancreas
need a multidisciplinary approach. For example, we’ll have patients
come in with terrible pancreatitis and cholangitis—infection
of the bile from a stone in the common bile duct. If such a patient
were operated on during the illness, they would run a high risk of
death. So, we’ll use ERCP to remove the stone and let the pancreatitis
settle down; and later the surgeons can operate to remove the diseased
gallbladder and the stones it contains, to prevent a recurrence of
the problem.”
What’s more, Baillie says, ERCP will become even more important
as researchers learn to better detect early malignancies of the bile
duct and pancreas—an especially virulent cancer—by testing
the cells that can be retrieved with the technique. “There are
promising techniques that will allow us to progress from what used
to be 25 percent sensitivity for picking up cancer, to 70 to 80 percent.
Ultimately, if we can identify people at high risk really early, we
may be able to change the natural history of the disease, by diagnosing
the precursor lesion and finding a way to reverse it.”
While the endoscopic techniques used by the gastroenterologists are
perhaps the most visible of their efforts, the division’s faculty
are also conducting pioneering basic research to understand GI disorders
including pancreatitis, hepatitis C, cancer, and Crohn’s disease.
And they are operating specialized services such as the Inflammatory
Bowel Disease Clinic not only to treat patients’ medical disorders,
but also to counsel them on how to cope with their disease.
So with all this expertise available, what of the “hot rock”
lodged in my belly? The colonoscopy report pronounced my colon an
“excellent preparation,” which made me rather proud. Annoyingly,
however, the report’s characterization of my dynamic self as
a “fifty-four-year-old man with dyspepsia” did make me sound
like a cranky old goat, which I did not particularly appreciate. But
gradually, as I took my gastroenterologist’s advice to lay off
caffeine and aspirin, that hot rock shrank away to almost nothing.
And, when I quit taking a joint-fortifying glucosamine supplement,
the rock disappeared altogether.
• continues on page two
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