Colorectal Cancer Screening with Case

00:01 Welcome.

00:02 Today we'll talk even further about disorders of the large bowel.

00:07 So we'll start with the case.

00:09 A 49-year-old man is seen in clinic for a routine visit.

00:13 He feels well with no symptoms.

00:15 He has a past medical history of hypertension, and a 20-pack year smoking history.

00:20 His father was diagnosed with colorectal cancer at age 58, so he is worried about his chances of having colon cancer.

00:29 He has heard there are many types of screening tests and is interested in the tests with the best ability to rule out cancer.

00:36 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.

00:49 In general, so he's 49, in general at least in the U.S., we begin colorectal cancer screening usually at age 45.

00:57 Other society guidelines may recommend to start screening at age 50. Per the U.S. guidelines, he is due for screening.

01:05 In addition, he does have a first-degree relative with colorectal cancer diagnosed at age 58, so this is another indication to screen sooner.

01:15 In addition, it is important to note, that he asked for the test with the best sensitivity.

01:20 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.

01:30 So, as we said earlier, in general we start screening for colorectal cancer between age 45 to 75.

01:37 You might start sooner or later depending on different risk factors and which regional guidelines you are using.

01:43 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.

02:03 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.

02:24 So diet high in fat, high in red meat but low in fiber can place you at high risk for colorectal cancer.

02:33 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.

02:43 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.

02:56 You may also do a CT colonography.

02:59 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.

03:11 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.

03:22 So now let's compare and contrast all of these variable tests.

03:27 These is one test called the fecal immunochemical test or FIT test.

03:30 It is done very similarly to the FOBT that we mentioned done before.

03:34 In general, it is done every year.

03:37 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.

03:45 The disadvantage, unfortunately is that it has a low sensitivity for detecting cancer.

03:51 An FOBT or fecal occult blood test is very similar in that it's done annually.

03:56 It is also non-invasive and convenient for patients but again, has low sensitivity.

04:03 Next, you could offer a CT colonography.

04:05 This is typically done every 5 years.

04:08 It is non-invasive since it's just a CT scan.

04:11 But, because it's just a CT scan, there's no ability to intervene if you find something suspicious.

04:19 You might also consider sigmoidoscopy This is usually done every 5 years.

04:24 It has excellent sensitivity for detecting abnormalities but is limited only to the sigmoid colon.

04:31 In addition it is invasive, it requires a bowel prep.

04:35 And as we mentioned, it really only visualizes the sigmoid colon.

04:39 So it's a bit limited in its reach.

04:43 And then lastly, a colonoscopy.

04:45 It’s really the gold standard for screening, it should be done every 10 years.

04:49 It has the highest sensitivity, of all of these tests.

04:53 The disadvantages, are that it too is invasive and requires a bowel prep.

05:01 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.

05:15 So now that we know that, let’s go back to our case.

05:18 We have a 49-year-old man who is asking about the best test to rule out cancer.

05:24 He does have a first-degree relative with cancer diagnosed at age 58, which might prompt you to consider your screening sooner.

05:32 In addition, in the U.S., guidelines support starting screening at age 45, so he should begin screening now.

05:41 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.

05:58 Colonoscopy has the highest sensitivity.