By A. Qureshi,
Consultant General &
Colorectal Surgeon,
Sunway Medical Centre, Petaling Jaya
Colorectal cancer is the third most common
cause of cancer deaths in Malaysia. Data from the Ministry
of Health Malaysia confirms an increase of colorectal cancer
admission rate from 8.1% (1973 cases) in 1987 to 11.9% (4215
cases) in 1995. Rectal cancer alone constituted for 50% of
colorectal admission and colorectal cancer deaths. The
incidence of colorectal cancer in Malaysia is 10-15 cases
per 100,000. The mean age at presentation in the western
developed nations is 60-65 years. However, in Malaysia this
figure is approximately 10 years earlier. There is evidence
to suggest that colorectal carcinoma is more common amongst
the Chinese while the age of presentation is earlier amongst
the Malays, and other indigenous groups of East Malaysia.
WHO IS
AT RISK OF COLORECTAL CANCER?
Although colorectal cancer may occur at any age, more than
90% of patients with colorectal carcinoma are over age 40,
at which point the risk doubles every ten years. Important
risk factors other than age include a family history of
colorectal cancer and polyps and a personal history of
ulcerative colitis, colon polyps or cancer of other organs,
especially of the breast or uterus.
HOW DOES COLORECTAL CANCER START?
Most colon and rectal cancers start as small
growths called polyps. These are pre-malignant (benign)
growths that occur on the bowel wall and may eventually
increase in size and become cancer. Removal of these benign
polyps while can prevent the development of colorectal
cancer.
WHAT ARE THE SYMPTOMS OF COLORECTAL CANCER?
The most common symptoms are
an alteration in bowel habit such as constipation, rectal
bleeding and a sensation of incomplete emptying of the
bowels. It is important to note that these symptoms are also
common in other diseases, so it is important that the
patient receives a thorough examination by a specialist
should these symptoms be present. Abdominal pain and weight
loss are usually late symptoms indicating possible extensive
disease. Many polyps and early cancers fail to produce
symptoms and thus it is important that if the patient has
any of the risk factors, a specialist consultation is made.
WHAT IS CONSTIPATION?
Constipation is a symptom that has different
meanings to different individuals. Most commonly, it refers
to infrequent bowel movements, but it may also refer to a
the passage of hard motions, a decrease in the volume of
stool, the need to strain to have a bowel movement, a sense
of incomplete evacuation, or the need for enemas,
suppositories or laxatives in order to maintain regularity.
About 80
percent of people suffer from constipation at some time
during their lives, and brief periods of constipation are
normal. Constipation may be diagnosed if bowel movements
occur fewer than three times weekly on an ongoing basis.
WHEN SHOULD I SEE A DOCTOR ABOUT
CONSTIPATION?
Any persistent change in
bowel habit - increase or decrease in frequency or size of
stool or an increased difficulty in evacuating - warrants
medical advice. Whenever constipation symptoms persist for
more than three weeks, you should consult your doctor. If
blood appears in the stool, consult your specialist right
away.
HOW IS COLORECTAL CANCER TREATED?
Colorectal cancer requires surgery in nearly
all cases for complete cure. In some patients, radiotherapy
and chemotherapy are sometimes used in addition. In the
early stages of colorectal cancer, 80-90% is cured if the
cancer is detected and treated. However, the cure rate
drops to 50% or less when diagnosed in the later stages.
Only a small number of patients, less than 5% of all
colorectal cancer patients, require a stoma, the surgical
construction of an artificial bowel opening on the abdomen.
WHAT IS A STOMA?
A stoma is a man made opening
of the bowel to the surface of the abdomen. The most common
types of stoma in intestinal surgery are an "ileostomy"
(connecting the small intestine to the skin) and a
"colostomy" (connecting the large intestine to the skin). A
stoma may be temporary or permanent. A temporary stoma can
be closed at a second operation a few months later. A
permanent stoma may be required when disease, or its
treatment, impairs normal intestinal function, or when the
muscles that control the anus do not work properly or
require removal. The most common cause of this is due to a
low rectal cancer.
CAN COLON CANCER BE PREVENTED?
Prevention of colorectal cancer can be
attempted in two ways, modification of diet and colonoscopic
intervention. A high fiber, low animal fat diet is the only
dietary measure that helps prevent colorectal cancer. Once
polyps are detected at colonoscopy, a simple outpatient
procedure of removing these polyps during the colonoscopy
can reduce the risk of developing colorectal cancer.
WHAT IS A COLONOSCOPY?
Colonoscopy is a method of
looking at the lining of the colon and rectum. It is a
simple, safe and effective means of visually examining the
entire lining of the colon and rectum, using a long,
flexible, tubular instrument. It is used to diagnose colon
and rectum problems as well as to perform biopsies and
remove colon polyps. Most colonoscopies are done on an
outpatient basis, under sedation, with minimal inconvenience
and discomfort.
WHO SHOULD HAVE A COLONOSCOPY?
A colonoscopy is performed on
patients with suspected colon and rectum problems. Patients
with the following symptoms are usually advised to undergo a
colonoscopy:
-
Rectal
bleeding
-
Altered
bowel habit
-
To
confirm findings of polyps or tumors located with a barium
enema exam
-
Monitor
patients with a past history of colon polyps or cancer
-
Examine
patients who test positive for blood in the stool
HOW IS COLONOSCOPY PERFORMED?
Prior to a colonoscopy, the
bowel must first be thoroughly cleansed of all fecal
residue. This is done either the evening before or the
morning of the colonoscopy. Sedation is given prior to the
colonoscopy to relieve anxiety and
discomfort. The colonoscope is inserted through the
anus and carefully guided through the entire length of the
large bowel (colon & rectum). When required, polyps can be
removed or biopsies taken.
The entire procedure usually takes 10-20
minutes. Following the colonoscopy, there may be some slight
discomfort due to the gas insufflation during the
colonoscopy. This quickly improves with the expulsion of
the gas. The patients can resume their regular diet later
that same day.
CAN HEMORRHOIDS LEAD TO COLON CANCER?
No, but hemorrhoids may
produce symptoms similar to colon polyps or cancer. Should
you experience these symptoms, you should have them examined
and evaluated by a specialist without delay.
Editor’s note:
There are other tests for screening for colon cancer. The
barium enema used to be the primary method until the advent
of colonoscopy. Now, virtual colonoscopy (CT scan images of
the abdomen with computer reconstruction of the colon) is
being studied for its ability to screen for colon cancer as
well.
For more information –
http://www.cancer.gov/cancerinfo/types/colon-and-rectal
National Cancer Institute of
America’s website with information about
detection, symptoms, diagnosis, and treatment of colon and
rectal cancer |
