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Cancer Home Page
Once a
colon cancer is diagnosed, the primary treatment is removal. In
most cases this requires surgery, but if the cancer is found at
a very early stage, when it has not grown beyond the polyp where
it started, it might be treated simply with complete removal of
the polyp through the colonoscope. When the polyp is removed,
it is examined by a pathologist with a microscope. If the
cancer cells are only seen in the tip of the polyp but not at
the base where it was cut across, then nothing else needs to be
done. Your doctor will recommend a repeat colonoscopy much
sooner though, to monitor closely for any additional polyps.
If the
cancer has grown into the base of the polyp or beyond, a segment
of the colon needs to be removed. Many people seem surprised at
how much colon is to be removed in such cases. The reason for
removing an entire segment has to do with how colon cancer grows
and spreads. The first place that colon cancer cells might
spread is into lymph nodes near the colon. These lymph nodes
are found along the blood vessels that supply the colon, and
these blood vessels and lymph nodes are located in something
called the mesentery of the colon. This mesentery is a thick
membrane of fatty tissue connecting the colon (and small bowel)
to the back of the abdominal cavity where the blood supply
originates. In order to remove enough of the lymph nodes, one
has to remove this mesentery, including the blood vessels
supplying that part of the colon. And so, the amount of colon
removed is determined by which major blood vessels are removed.
Since there are about 4 major blood vessels supplying the
different colon segments, the amount of colon removed basically
is determined by which segment of the colon the cancer is
located.
The first
segment of colon is on the right side of your abdomen, and so is
called the right colon (or ascending colon, which includes
something called the cecum), and is supplied by the right colic
artery. The next segment of the colon crosses the upper abdomen
from right to left and is called the transverse colon, supplied
by the middle colic artery. The next part of the colon descends
down on the left side of the abdomen and is called the left
colon (or descending colon), and is supplied by the left colic
artery. The next segment forms an S shape called the sigmoid
(like the Greek letter for S, or “sigma”), and is supplied by
the sigmoid artery. Beyond the sigmoid colon is where the
rectum begins.
So, if the
cancer is located in the cecum or ascending colon, a right
colectomy is the usual procedure. If the cancer is in the
transverse colon, the surgery will remove at least half of the
transverse colon, and often the right or some of the left
depending on whether the cancer is closer to the right or left
side. If the cancer is in the left, or descending colon, the
left colon will be removed, and so forth.
“Open”
versus “laparoscopic” colectomy
In order
to remove a portion of the colon, some sort of incision must be
made of course. This traditionally has involved making a fairly
long opening into the abdomen, to allow the surgeon’s hands to
get down and around the colon and its blood supply. This method
has come to be referred to as the “open” or “traditional”
technique, in contrast to a newer method now available. Since
the early 1990’s new techniques have been developed which allow
the surgeon to use smaller incisions, using small instruments
rather than his hands to do the procedure. These various
techniques are referred to as “laparoscopic” or “laparoscopic
assisted” procedures. In many cases, the necessary procedure
can be achieved in this way, through a smaller incision. Your
surgeon will likely discuss these different options with you,
and decide which technique seems best for you.
“Bowel
prep” (cleansing of the colon) for surgery
In the
past, anytime a portion of the colon was to be surgically
removed, the patient had to cleanse their colon, just like what
is done for colonoscopy. This involves drinking only clear
liquids for 1-3 days, and taking some laxatives or purgatives.
We now know that it doesn’t usually make any difference whether
the colon is “cleaned out” or not for the surgery, the outcome
seems to be the same. And so, in most cases, the surgeons at
DeKalb Surgical Associates will not make you go through the
“bowel prep” prior to your surgery. But there are situations
where it still is necessary, so you can discuss this further as
you prepare for your surgery.
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