00:01
Welcome.
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Today we'll talk even further
about disorders of the large bowel.
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So we'll start with the case.
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A 49-year-old man is seen
in clinic for a routine visit.
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He feels well with no symptoms.
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He has a past medical history of hypertension,
and a 20-pack year smoking history.
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His father was diagnosed
with colorectal cancer at age 58,
so he is worried about his
chances of having colon cancer.
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He has heard there are
many types of screening tests
and is interested in the tests with
the best ability to rule out cancer.
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His vitals are normal and
physical exam is unremarkable.
00:40
So which screening test for colorectal
cancer is the best recommendation for him?
Before we answer that, let's
identify some key points in this case.
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In general, so he's 49, in general we begin
colorectal cancer screening usually at age 50.
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However, he does have a first degree relative
with colorectal cancer diagnosed at age 58,
so we might consider screening a bit sooner.
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How soon? We'll find out.
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In addition, it is important to note, that he
asked for the test with the best sensitivity.
01:12
So here, as in with the real life patient, you
always want to ask what the patient desires
and try to determine which
test meets their needs best.
01:23
So, as we said earlier, in general we start
screening for colorectal cancer between age 50 to 75.
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You might start sooner
depending on different risk factors,
how much sooner depends
on which guidelines you use.
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So, some factors you might
use to help you decide are:
whether they have an
inflammatory bowel disease,
if they have a first-degree
relative with colorectal cancer
or an advanced adenoma that
was diagnosed before age 60,
whether they have a
familial cancer syndrome,
or African American race.
01:59
So some other major risk factors for colorectal
cancer include advanced age, generally over 50,
a personal history of adenomatous polyps,
inflammatory bowel disease,
a family history mostly a first
degree relative with colorecatal cancer,
and dietary factors also play a role.
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So diet high in fat, high in red meat but low in fiber
can place you at high risk for colorectal cancer.
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So let's talk now about the various types of screening
tests we have available for colorectal cancer
The first type of test is the
fecal occult blood test or an FOBT.
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This is simply a small card on which a
patient can place a small stool sample
and then they can easily mail it in and
have it analyzed for the presence of occult blood.
02:52
You may also do a CT colonography.
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This is a 3-dimensional
simulation of the colon,
so it's a CT that we do to then
get a look to the inside of the colon.
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Lastly, you may also do a
sigmnoidoscopy or colonoscopy
which is really the most direct way to look at the
colon and be able to intervene at the same time.
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So now let's compare and
contrast all of these variable tests.
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These is one test called
the fecal immunochemical test or FIT test.
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It is done very similarly to the
FOBT that we mentioned done before.
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In general, it is done every year.
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The advantage are that it is noninvasive
and it is very convenient for patients to do
since they are simply
mailing in a stool sample.
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The disadvantage, unfortunately is that it
has a low sensitivity for detecting cancer.
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An FOBT or fecal occult blood test is
very similar in that it's done annually.
03:52
It is also non-invasive and convenient
for patients but again, has low sensitivity.
03:58
Next, you could offer a CT colonography.
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This is typically done every 5 years.
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It is non-invasive since it's just a CT scan.
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But, because it's just a CT scan, there's no
ability to intervene if you find something suspicious.
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You might also consider sigmoidoscopy
This is usually done every 5 years.
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It has excellent sensitivity for detecting
abnormalities but is limited only to the sigmoid colon.
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In addition it is invasive,
it requires a bowel prep.
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And as we mentioned, it really
only visualizes the sigmoid colon.
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So it's a bit limited in its reach.
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And then lastly, a colonoscopy.
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It’s really the gold standard for screening, it
should be done every 10 years.
04:45
It has the highest
sensitivity, of all of these tests.
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The disadvantages, are that it too
is invasive and requires a bowel prep.
04:56
As a quick aside,
you should always remember that if a patient does have FOBT
or a FIT test that turns out positive for occult blood,
they must then be referred for colonoscopy.
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So now that we know that,
let’s go back to our case.
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We have a 49-year-old man who is
asking about the best test to rule out cancer.
05:20
He does have a first-degree relative
with cancer diagnosed at age 58,
which might prompt you to
consider your screening sooner.
05:27
So, which screening test do we recommend for him?
Since he's at elevated risk for colorectal
cancer, with his first-degree relative,
you should consider
screening with a colonoscopy
since he's asking about the test
with the best ability to rule out cancer.
05:45
Colonoscopy has the highest sensitivity.