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COLON CANCER
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BASIC INFORMATION
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PREVENTION
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DIAGNOSIS
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TREATMENT
BASIC INFORMATION
Colon cancer occurs when the cells in the colon or rectum grow and multiply
uncontrollably, damaging surrounding tissue and interfering with the normal function of
the colon or rectum. Colon cancer is the third most common cancer diagnosed in the
United States. Most colon cancers (about 70%) are found in the first six feet of the large
intestine. The other 30% occur in the last 10 inches of the large intestine (rectum).
Collectively they are referred to as colorectal cancers.
One in 19 Americans will be diagnosed with colon cancer in their lifetime, for an overall
risk of 5.4%. Although colon cancer affects men and women equally, rectal cancer is
more common in men. When colon and rectal cancers are found early, there is nearly a
90% chance for cure.
About 80% of colon cancer cases are sporadic, meaning that cause is nonspecific or
undetermined. The other 20% of colon cancers are hereditary. People who have a firstdegree family member with colon cancer are more likely to be affected themselves.
About 5% of this group has a predisposition to hereditary non-polyposis colorectal cancer
(Lynch syndrome), a rare disease that generally strikes people aged 30 to 50.
Symptoms
There often are no symptoms of colon cancer in its early stages. Most colon cancers
begin as a polyp, a small non-cancerous growth on the colon wall that can grow larger
and become cancerous. As polyps grow, they can bleed or obstruct the intestine.
Symptoms include:
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Rectal bleeding
Blood in the stool or toilet after a bowel movement
Prolonged diarrhea
A change in size or shape of your stool
Abdominal pain or a cramping pain in your lower stomach
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A feeling of discomfort or urge to have a bowel movement when there is no need
Many colon symptoms are not cancer, but if you notice one or more of these symptoms
for more than two weeks, see your doctor.
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PREVENTION
Risk Factors
Many factors may influence the development of colon cancer, including:
Age: Colon cancer is most common in people over 50.
Family history: Your risk is higher with a family history (especially parent, sibling) of
colon cancer or adenomatous polyps.
Personal history: Your risk is higher with a personal history of inflammatory bowel
disease (Crohn’s disease or colitis), colon cancer or adenomatous polyps.
Weight: Lack of physical activity and obesity are risk factors.
Diet: A high-fat diet, particularly animal fats, may increase your risk. Diets high in fruits
and vegetables are thought to decrease your risk.
Cigarette smoking and alcohol: Your risk may be higher if you smoke or drink alcohol.
Reducing Your Risk
You can take action to reduce your risk of developing colon cancer by:
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Eating at least five servings of fruits and vegetables per day
Limiting your fat intake to no more than 30% of your total daily calories
Exercising regularly
Maintaining your ideal weight
Quitting smoking
Limiting alcohol consumption
Screening Guidelines
Cancer screenings are medical tests that are performed when a person has no symptoms.
Starting at age 50, men and women should follow one of the five examination schedules
below. All positive tests (FOBT, FIT, flexible sigmoidoscopy, barium enema) should be
followed up with a colonoscopy.
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Colonoscopy: Every 10 years (preferred by MD Anderson).
Fecal occult blood test (FOBT) or fecal immunochemical test (FIT): Every year.
Both tests are available in take-home versions.
Flexible sigmoidoscopy: Every five years.
Annual FOBT or FIT and flexible sigmoidoscopy: Every five years. Having both
tests is recommended over either test alone.
Double-contrast barium enema: Every five years.
People at moderate or high risk for colon cancer (e.g., strong family history) should talk
with their doctor about the need for a different testing schedule.
These screening guidelines are provided as a guide. If results of these exams suggest
cancer, more extensive diagnostic tests of the colon or rectum should be conducted. More
frequent exams are needed if polyps (precancerous lesions) are found. In individuals at
increased risk with a family history of colon cancer or polyps or a personal history of
inflammatory bowel disease, screening may need to begin earlier.
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DIAGNOSIS
Diagnosing Colon Cancer
There are many methods for diagnosing colon cancer. Some of these procedures are also
used as screening devices to detect colon cancers in the early stages, when treatment is
more successful.
Fecal Occult Blood Test (FOBT): A stool sample is examined for traces of blood not
visible to the naked eye. If you do see blood in your stool, contact your doctor
immediately.
Fecal Immunochemical Test (FIT): FIT is a take-home test that detects blood proteins
in stool. A small, long-handled brush is used to collect a stool sample, which is placed on
a test card and sent to a lab for examination.
Sigmoidoscopy: A tiny camera with flexible plastic tubing is inserted into the rectum,
providing a view of the rectum and lower colon. This procedure can also be used to
remove suspicious tissue for examination.
Colonoscopy: A colonoscope is a longer version of a sigmoidoscope, and can examine
the entire colon. Patients must be sedated for a colonoscopy.
Virtual colonoscopy: Instead of a scope, physicians use imaging technology to view the
colon. Air is pumped into the colon to expand it for better imaging. Virtual colonoscopy
can be performed with computed tomography (CT) or magnetic resonance imaging
(MRI).
Double Contrast Barium Enema (DCBE): Barium is a chemical that allows the bowel
lining to show up on X-ray. A barium solution is administered by enema; then the patient
undergoes a series of X-rays.
Digital Rectal Exam: The doctor inserts a gloved finger into the rectum to feel for
polyps or other irregularities.
Carcinoembryonic Antigen (CEA): A blood test that determines the presence of CEA,
a substance, or tumor marker, produced by some cancerous tumors. This test can also be
used to measure tumor growth or assess if cancer has recurred after treatment.
Staging
(Source: National Cancer Institute)
Stage 0: Abnormal cells are found in the innermost lining of the colon or rectum. These
abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also
called carcinoma in situ.
Stage I: Cancer has formed and spread beyond the innermost tissue layer of the colon or
rectum wall to the middle layers. Stage I colon cancer is sometimes called Dukes A colon
cancer.
Stage II: Colon cancer is divided into stage IIA and stage IIB. Stage II colon cancer is
sometimes called Dukes B colon cancer.
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Stage IIA: Cancer has spread beyond the middle tissue layers of the colon or
rectum wall or has spread to nearby tissues around the colon or rectum
Stage IIB: Cancer has spread beyond the colon or rectum wall into nearby organs
and/or through the peritoneum
Stage III: Colon cancer is divided into stage IIIA, stage IIIB and stage IIIC. Stage III
colon cancer is sometimes called Dukes C colon cancer.
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Stage IIIA: Cancer has spread from the innermost tissue layer of the colon or
rectum wall to the middle layers and has spread to as many as three lymph nodes
Stage IIIB: Cancer has spread to as many as three nearby lymph nodes and has
spread:
o beyond the middle tissue layers of the colon or rectum wall
o to nearby tissues around the colon or rectum
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beyond the colon or rectum wall into nearby organs and/or through the
peritoneum
Stage IIIC: Cancer has spread to four or more nearby lymph nodes and has
spread:
o to or beyond the middle tissue layers of the colon or rectum wall
o to nearby tissues around the colon or rectum
o to nearby organs and/or through the peritoneum.
Stage IV: Cancer may have spread to nearby lymph nodes and has spread to other parts
of the body, such as the liver or lungs. Stage IV colon cancer is sometimes called Dukes
D colon cancer.
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TREATMENT
Treatment
Surgery
Surgery is the most common treatment for colon and rectal cancers. Depending on the
stage and location of the tumor, different surgical methods are used.
Local excision: If tumors are small enough, they may be removed with minimally
invasive surgery. Tiny incisions are made in the abdomen. A miniature camera and
surgical instruments are inserted. The surgeon uses computer imaging to locate and
remove the tumor.
Polypectomy: Suspicious or cancerous polyps on the colon wall can easily be removed.
A colonoscope is a long tube with a camera in the end. The colonoscope is inserted in the
rectum and guided to the area requiring treatment, and a tiny, scissor-like instrument
removes the polyp.
Colectomy: Surgeons remove the cancerous portion of the colon, along with a margin of
healthy tissue on either side, and then join the colon back together. This procedure is also
called a hemicolectomy or segmental resection.
Resection & colostomy: If the colon cannot be rejoined after removing the cancer,
surgeons will perform a colostomy. A stoma (hole) is cut in the abdominal wall and
attached to a segment of colon. Bodily waste goes through the stoma into a plastic bag
outside the body. Colostomies may be temporary, allowing the bowel to heal before
resection. However, about 15% of colostomies are permanent.
Radiation Therapy
Radiation therapy may be used to destroy any colon or rectal cancer cells that remain
after surgery. Radiation is used most often on rectal cancers, or those that cannot be
treated with surgery. It can also be used to relieve cancer symptoms.
Chemotherapy
Chemotherapy can be used to shrink rectal tumors before surgery, or to lengthen survival
time after surgery. Chemotherapy is generally not effective for advanced or recurring
colon cancers.
Targeted Therapy
Researchers are developing new drugs that are designed to seek out and destroy specific
types of cancer cells without affecting healthy cells. Drugs such as Avastin, Erbitux and
Vectibix are showing promise in treating colon cancer.
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