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Colorectal Cancers
Recent epidemiologic studies, which track and analyze the
cause and spread of diseases, suggest that approximately 130,000
Americans will be diagnosed with colorectal cancer each year.
Of those diagnosed, 55,000 will die of their disease. According
to these statistics, colorectal cancer is the second leading
cause of cancer death in the United States, after lung cancer,
and the third most prevalent cancer overall. If not detected
and treated in time, colorectal cancer will strike 6% of the
American adult population.
What is colorectal cancer?
What are the symptoms of colorectal cancer?
Who is most at risk for developing colorectal
cancer?
How is colorectal cancer detected?
What are the pros and cons of sigmoidoscopy versus
colonoscopy?
What is the recommended frequency of screening
for colorectal disease in "normal risk" individuals?
How does this vary for high risk individuals?
What happens if I am diagnosed with colorectal
cancer?
What is colorectal cancer?
Cancer is a general term for various illnesses characterized
by abnormal growth of cells, forming malignant tumors, or
carcinomas, that can develop in many parts of the body and
commonly spread to other organs. If growths occur that are
not invasive, progressive or recurrent they are said to be
benign.
Numerous clinical studies, those that collect and analyze
patient treatment data, have proven that the precursor lesion
(a localized, structural abnormality) to colorectal cancer
is the adenomatous polyp. A polyp is an abnormal growth that
develops from the cells that line the colon, and protrudes
into the lumen, or central passageway of the colon, which
is essentially a tube. Some polyps are flat, or sessile, while
others, termed peduncular, have a stalk. While there are several
different types of polyps, generally only the adenomas are
precancerous. They account for 50% to 60% of all polyps.
Incidence of these precancerous lesions increases with age;
by age 50, one quarter of the American population will develop
adenomatous polyps. They can develop anywhere in the colon
but are most often found in the lower third of the large bowel.
If precancerous polyps are found and destroyed when small,
they never have the opportunity to become cancerous. For this
reason, the key strategy for maintaining colorectal health
is a proper screening program to detect and eliminate colonic
lesions before they become cancers.
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What are the symptoms of colorectal cancer?
Unfortunately, the majority of people with benign polyps
or early cancers rarely develop clearly recognizable symptoms
of the disease. But, symptoms to look out for include traces
of blood in the stool, fatigue, which results from chronic
(continuous) blood loss caused by the cancer, and change in
bowel habits.
The most commonly reported problem is rectal bleeding, which
is a very "non-specific" symptom. This means that
the bleeding can be attributed to many different causes, and
frequently those with colorectal cancer may blame any bleeding
they notice on hemorrhoids, fissures or other benign anal
problems.
Changes in bowel habits include narrower stools or a change
in frequency of bowel movements, including both constipation
or diarrhea. Newly developed constipation, an enlarging abdomen,
or abdominal discomfort and cramping may be caused by a colon
tumor that is partially blocking the bowel.
If the cancer is located in the rectum, symptoms may include
tenesmus, a feeling that you have not completely emptied after
a bowel movement, bleeding or discomfort in the pelvic region.
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Who is most at risk for developing colorectal
cancer?
All individuals are at risk for developing colorectal
cancer, but certain lifestyle habits have been proven to increase
one's risk of developing cancer.
A high-fat, low-fiber diet is thought to place a person at
higher risk for developing colon cancer. A diet deficient
in fruits and vegetables that provide fiber, and high in animal-based
fats may promote colorectal cancer. Similarly, a sedentary
lifestyle devoid of regular exercise, as well as tobacco smoking
and excessive alcohol consumption, may contribute to other
health complications and increase risk for developing colorectal
cancer.
Certain diseases are believed to place individuals at higher
risk. These include inflammatory bowel diseases such as ulcerative
colitis and Crohn's disease, inherited polyposis syndromes
like Gardner's syndrome or familial polyposis, and any of
the nonpolyposis colon cancer syndromes.
Anyone with a "first degree" relative (your mom,
dad or sibling) who has developed colon cancer is at increased
risk. This is especially influential if their cancer developed
at a younger age, i.e., less than age 50. Also, women who
have experienced breast, ovarian or uterine cancer may be
at increased risk for developing colon cancer.
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How is colorectal cancer detected?
Fortunately, there are easy methods for detecting colorectal
cancer in its early stages when the lesions are most curable.
Fecal occult blood testing (FOBT) is a simple test for detecting
the presence of blood in the stool. It involves testing two
samples from three consecutive stools after following a specific
diet. You may be familiar with the term Hemoccult¨ which
is the trade name for the test kit that is used. Your doctor
will process the sample to determine if there is blood in
the specimen which may not be visible, therefore the use of
the term "occult." If evidence of bleeding is found,
the next diagnostic examination would be a colonoscopy.
Flexible sigmoidoscopy is an examination of the lining of
the lower two feet of your descending colon, your sigmoid
colon and the rectum. The majority of colorectal cancers begin
in this area of the bowel. Sigmoidoscopies are routinely performed
in your doctor's office with the use of a lighted, flexible
fiberoptic endoscope. Prior to the examination cleansing of
the lower bowel is necessary, most often using enemas. There
is only slight discomfort during the procedure. When done
in the office, no sedation is required and you may drive immediately
afterwards and carry out normal activities.
If an abnormality is found, a colonoscopy at a later date
will be required to examine the remainder of the colon for
other growths, and to remove any polyps, known as "polypectomy",
or to biopsy any lesions not amenable to removal through the
colonoscope.
Double-contrast barium enema is an X-ray examination using
air and barium, a paste-like, opaque substance, which are
inserted through the rectum by use of an enema tube. The presence
of barium allows the X-rays to outline the shape and contour
of the colon's lining and indicate any suspicious lesions.
If found, colonoscopy will be necessary for visualization
and removal or biopsy of the lesion(s). Colonoscopy involves
direct visual examination of the lining of the entire colon.
Like flexible sigmoidoscopy, the endoscope used is a lighted,
flexible fiberoptic instrument. This examination is more extensive,
however, and requires a more extensive cleansing protocol.
Abnormalities such as polyps may be removed and precancerous
lesions thus cured. This examination takes longer but is also
minimally uncomfortable. It is performed in an endoscopy unit
where sedation is available to make you more relaxed. Your
blood pressure, heart rate and oxygenation are monitored during
the exam. Afterwards, you will need someone to drive you home,
but can eat immediately and resume all normal activities the
following day.
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What are the pros and cons of sigmoidoscopy
versus colonoscopy?
There is some controversy over how much of the colon needs
routine examination and how frequently the exams should be
carried out. Sigmoidoscopy allows examination of the lower
third of the large bowel. At colonoscopy, the entire colon
is examined from the anus all the way to the ileocecal valve,
the junction of the small intestine and the colon. About 65%
of all precancerous polyps are found in the distal (lower)
third of the colon which is within reach of the sigmoidoscope.
Those who favor sigmoidoscopy believe that if no polyps are
present in the sigmoid colon they are unlikely to exist in
the remainder of the colon and therefore, feel that colonoscopy
for such individuals is unnecessary.
The opposing viewpoint takes nothing for granted, believing
that the only way to be certain the colon is free of precancerous
polyps is to examine it completely.
The motivating factor behind this controversy is often economic.
Colonoscopy is a more involved and expensive procedure than
sigmoidoscopy. Those responsible for paying for colorectal
screening procedures usually support the use of sigmoidoscopy,
if anything, over the performance of routine full colonic
examination.
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What is the recommended frequency of screening
for colorectal disease in "normal risk" individuals?
Most authorities currently recommend screening for colorectal
cancer begin by the age of fifty. As mentioned above, standard
screening programs include:
FOBT annually, with sigmoidoscopy every 5 years, OR
colonoscopy every 5 to 10 years, OR
double contrast barium enema every 5 to 10 years combined
with sigmoidoscopy. A digital rectal examination should also
be done regularly by your primary care physician or gynecologist.
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How does this vary for high risk individuals?
For those with more than average risk for developing colorectal
cancer a more stringent screening schedule is necessary. You
are in this category if,
You have already been diagnosed and treated for adenomatous
polyp(s) or colon cancer.
There is a history of colon cancer and/or adenomatous polyps
in your family. Your personal risk will be highest if you
have a first degree relative (dad, mom or sibling) who has
had a colon polyp or cancer. If your grandparents, uncles,
aunts, or cousins have experienced colorectal cancer you are
probably at slightly higher risk for developing colon cancer
than the general population. Similarly, a family history of
other cancers such as ovarian, uterine, stomach, pancreas
and small bowel cancers may also indicate slightly higher
risk. If there is a family history of colon cancer occurring
at an early age, between 30 and 40 years, you should begin
regular screening before you reach age 50. We recommend starting
regular exams when you are 10 years younger than your family
member at diagnosis.
You suffer from inflammatory bowel disease, such as ulcerative
colitis or Crohn's disease, or a familial polyposis syndrome.
In this case, you should discuss with your physician your
increased need for early and complete evaluation.
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What happens if I am diagnosed with colorectal cancer?
The vast majority of people who develop colon cancer will
require surgical resection (removal) of a segment of the colon
or rectum. Rarely, if the cancer is confined within a polyp
that can be completely removed through the colonoscope, no
other therapy may be necessary at that point. However, follow
up colonoscopies at 1 to 3 year intervals would be advised.
When a colon resection is required, between 8 to 12 inches
of colon are usually removed; the goal is to remove the entire
segment of colon that contains the cancer. The segment's adjoining
mesentery, which contains the blood vessels and lymph nodes
that supply it, is also removed. This is because colon cancers
can involve the lymph nodes and invade the blood vessels directly.
Because the colon is on average four feet long and because
tumors can develop anywhere along its length, the segment
to be resected will vary from patient to patient. After the
segment is removed, the two remaining ends of the bowel are
joined together to reconnect the intestine. This reconnection
is called an anastomosis.
The only tumor location that prohibits anastomosis is the
very distal rectum, within a finger's reach of the anus. Those
few with tumors in this location have a number of treatment
options available; these are discussed in the section on rectal
cancer. Some patients may unfortunately require a complete
rectal resection, also called an abdominoperineal resection,
and a permanent colostomy.
Your surgeon performs a colostomy to create a small opening,
or stoma, in the abdominal wall through which feces exits
the body. Depending on the size of the rectal tumor it may
be possible to avoid this radical operation and treat the
tumor in a way which does not require colostomy. But, if a
stoma is necessary, specially trained nurses, in addition
to your physician, will assist in its initial care. Today,
this is simpler than in the past. The stoma nurse is a professional
trained in the care and teaching of patients requiring colostomy.
He or she is available for questions before or after your
surgery at Columbia Presbyterian, and is an invaluable source
of information, medical care and support.
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