I can’t overstress the importance of colonoscopy and screening colonoscopies. We typically do this in an
outpatient setting after a bowel prep. A bowel prep includes drinking some sort of an agent that will do
a volume cleansing of the colon as well as allow an easier manipulation and visualization of the colon.
Patients are placed on their side under visualization. Oftentimes, believe it or not, patients are awake
for this procedure so they can actually look at the entire colonoscopy as it is being performed.
Now, not every patient requires a colonoscopy. There are centers that will either do a barium enema or fecal
occult blood testing. Only if the fecal occult blood testing is positive will they pursue either a flexible
sigmoidoscopy or a colonoscopy. Nevertheless, colonoscopy is quite standard. With a normal colonoscopy
with averaged-risk patients, you don’t require another one for another 10 years.
In cases of incomplete colonoscopy results, the PILLICAM can be used,
which is a small camera in the shape of a pill that the patient swallows.
It takes pictures that can be used for diagnosis.
Now that you've diagnosed colon cancer, what’s the next step? Well, before offering surgery, we have to make sure that the
patient has not metastasized to other organs. Liver function testing is very important
because it is a common area of metastases particularly alkaline phosphatase. Additional metastatic
workup can include chest X-rays, cross-sectional images. On this set of abdominal CTs, you’ll notice
that multiple liver lesions are showing. The volume of lesions is suggestive of metastases as opposed
to a solitary liver lesion. Here’s a description of what happens in surgery. We do what’s called an oncologic
surgical resection which means we want to take the segment of the colon that contains the tumor
obviously but we also want to take its draining blood supply as well as very importantly its lymph
node basin. Now as you progress from the left of the slide to the right of the slide, you’ll notice that
we’re going from the right side of the colon to the left side of the colon. Some patients may require 5-FU based
chemotherapy depending on the depth or penetration or stage of the cancer. Recall that colon
and rectal cancer are treated very similarly except for radiation. We can’t radiate colon without
irradiating the small intestines and therefore, it has had limited utility. However, the rectum can be
irradiated and therefore, rectal cancer is often treated with radiation. 5-FU, leucovorin are both common
chemotherapy bases. Tumor depth is very important. This is also an important review of
the different layers of the colon. T1 disease invades submucosa. T2 invades the muscularis propria
commonly called the MP. T3, into pericolonic fat. And T4 is a full-thickness penetration of the surface
of the visceral peritoneum or frank, direct invasion to surrounding organs whether that’d be a bladder
or prostate. Stages of the colon go by the AJCC TNM staging process. You can look that up on the internet.
Based on the stage of the colon cancer, whether it’s a stage 1 or 4, has significant five-year survival
prognosis. You can see that patients with stage 1 or early disease have far better five-year survivals
than a patient who has stage 4 or metastatic colon cancer. We talked about the importance of colonoscopy.
It should be conducted every 10 years beginning at the age of 50. If it’s normal,
then one can forego another one for 10 years. There’s an interesting subset of patients where we
talk about colonoscopy before a surgery. This is the classic patient who presents with potential
right lower quadrant abdominal pain. You get cross-sectional images, concerned for either diverticulitis
or appendicitis and yet on the cross-sectional image, you see what’s called a phlegmon. A phlegmon
is a collection of inflammation that hasn’t completely progressed to an abscess. These patients may
eventually develop a disease that requires surgery. However, before offering surgery to those patients,
you must offer them a colonoscopy to search for colon cancer. This is the classic scenario of a right
lower quadrant phlegmon if presented to you on the examination as a clinical scenario that patients
require screening for colon cancer before definitive operation whether it’s diverticulitis or appendicitis.
Let’s review some very high-yield information. Again, Lynch syndrome and the multiple Amsterdam
criteria as well as the Bethesda criteria. Remember the very predictable pattern of gene mutation from polyp
to cancer sequence. Recall that patients with FAP and multiple colon polyposes have near 100% risk of
colon cancer and therefore, we offer surgery to them. Thank you again for joining me on this
discussion of colon cancer.