Digestive Disorders
Colon and Rectal (Colorectal) Cancer
What is colorectal cancer?
Colorectal cancer is malignant cells found in the colon or rectum. The colon
and the rectum are part of the large intestine, which is part of the digestive
system. Because colon cancer and rectal cancers have many features in common,
they are sometimes referred to together as colorectal cancer. Cancerous tumors
found in the colon or rectum also may spread to other parts of the body.
Colorectal cancer is the second leading cause of cancer deaths in the United
States. However, the number of new cases of colorectal cancer and the number
of deaths due to colorectal cancer have decreased, which is attributed to increased
sigmoidoscopic screening and polyp removal.
What are the symptoms of colorectal cancer?
The following are the most common symptoms for colorectal cancer, however, each
individual may experience symptoms differently.
People who have any of the following symptoms should check with their physicians,
especially if they are over 40 years old or have a personal or family history
of the disease:
- a change in bowel habits such as diarrhea, constipation, or narrowing of
the stool that lasts for more than a few days
- rectal bleeding or blood in the stool
- cramping or gnawing stomach pain
- decreased appetite
- vomiting
- weakness and fatigue
- jaundice (yellowish coloring) of the skin or sclera of the eye
The symptoms of colorectal cancer may resemble other conditions, such as infections,
hemorrhoids, and inflammatory bowel disease. It is important to talk to the
physician since finding colorectal cancer early makes successful treatment more
likely. It is also possible to have colon cancer and not have any symptoms.
What are the risk factors for colorectal cancer?
Risk factors may include:
- age
Most people who have colorectal cancer are over age 50, however, it can occur
at any age.
- diet
Colorectal cancer is associated with a diet high in fat and calories, and
low in fiber.
- polyps
Benign growths on the wall of the colon or rectum are common in people over
age 50, and are believed to lead to colorectal cancer.
- personal history
People who have had colorectal cancer, as well as ovarian, uterine, or breast
cancers, have a slightly increased risk for colorectal cancer.
- family history
People with first-degree relatives who have had colorectal cancer have an
increased risk for colorectal cancer.
- ulcerative colitis
People who have ulcerative colitis, inflamed lining of the colon, have an
increased risk for colorectal cancer.
What causes colorectal cancer?
The exact cause of most colorectal cancer is unknown, but the known risk factors
listed above are the most likely causes. Less than 10 percent of colorectal
cancers are caused by inherited gene mutations.
People with a family history of colorectal cancer, may wish to consider genetic
testing. The American Cancer Society suggests that anyone undergoing such tests
have access to a physician or geneticist qualified to explain the significance
of these test results.
Prevention of colorectal cancer:
Although the exact cause of colorectal cancer is not known, it is possible to
prevent many colon cancers through:
- diet and exercise
It is important to manage the risk factors you can control, such as diet and
exercise. Eating more fruits, vegetables, and whole grain foods and avoiding
high-fat, low-fiber foods, plus appropriate exercise, even small amounts on
a regular basis, can be helpful.
- drug therapy
Some studies have shown that low doses of nonsteroidal anti-inflammatory drugs
(NSAIDs) such as aspirin, and estrogen replacement therapy for post-menopausal
women may reduce the risk of colorectal cancer. Discuss this with your physician.
- screenings
Perhaps most important to the prevention of colorectal cancer is having screening
tests at appropriate ages. Because some colorectal cancers cannot be prevented,
finding them early is the best way to improve the chance of a successful treatment,
and reduce the number of deaths caused by colorectal cancer.
The following screening guidelines can lower the number of cases of the disease
and can also lower the death rate from colorectal cancer by detecting the
disease at an earlier, more treatable stage.
Methods of screening for colorectal cancer:
Screening methods for colorectal cancer, for people who do not have any symptoms
or strong risk factors, include:
- digital rectal examination (DRE) - a physician or health care provider
inserts a gloved finger into the rectum to feel for anything unusual or abnormal.
fecal occult blood test - a sample of stool is examined for blood. A test
kit will explain how to take a sample at home. It is then returned to the
physician's office to be checked.
- sigmoidoscopy - a slender, flexible, hollow, lighted tube is placed
into the rectum allowing the physician to look at the inside of it and part
of the colon for cancer or for polyps.
- colonoscopy - a long, flexible, lighted tube (much longer than a
sigmoidoscope) about the thickness of a finger is inserted through the rectum
up into the colon, allowing the physician to see the colon lining.
- barium enema with air contrast (also called a double contrast barium
enema) - barium sulfate, a chalky substance used to partially fill and open
up the colon, is given in the anus and x-rays are made.
Diagnostic procedures for colorectal cancer:
In addition to a complete medical history and physical examination, diagnostic
procedures for colorectal cancer may include:
- digital rectal examination (DRE)
- fecal occult blood test
- sigmoidoscopy
- colonoscopy
- barium enema
- biopsy
- CEA assay to measure a protein called carcinoembryonic antigen, which is
sometimes higher in patients who have colorectal cancer.
Treatment for colorectal cancer:
Specific treatment will be determined by your physician(s) based on:
- your age, overall health, and medical history
- extent of the disease
- your tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
Treatment choices for the person with colon cancer depend on the stage of the
tumor -- if it has spread and how far. When the disease has been found and staged,
your physician will suggest a treatment plan. Treatments may include:
- colon surgery
The main treatment for colon cancer and the usual operation is called a segmental
resection, in which the cancer and a length of normal tissue on either side
of the cancer are removed, as well as the nearby lymph nodes.
- radiation therapy
Radiation therapy is the use of high energy radiation to kill cancer cells
either after surgery, to kill small areas of cancer that may not be seen during
surgery, or instead of surgery. Radiation may also be used to ease (palliate)
symptoms such as pain, bleeding, or blockage. There are two ways to deliver
radiation therapy:
- External beam radiation uses radiation from outside the body, which
is focused on the cancer.
- Internal radiation therapy uses small pellets of radioactive material
placed directly into the cancer.
- chemotherapy
- Drugs (medications) are given into a vein or by mouth to kill cancer cells
throughout the body. Studies have shown that chemotherapy after surgery can
increase the survival rate for patients with some stages of colon cancer.
Chemotherapy can also help relieve symptoms of advanced cancer.
Anatomy of the colon:
The colon is the first six feet of the large intestine. It has four sections:
- The first section is called the ascending colon. It extends upward
on the right side of the abdomen.
- The second section is called the transverse colon since it goes across
the body to the left side.
- There it joins the third section, the descending colon, which continues
downward on the left side.
- The fourth section is known as the sigmoid colon because of its S-shape.
The sigmoid colon joins the rectum, which in turn joins the anus, or the opening
where waste matter passes out of the body.
What is a risk factor?
A risk factor is anything that may increase a person's chance of developing
a disease. It may be an activity, such as smoking, diet, family history, or
many other things. Different diseases, including cancers, have different risk
factors.
Although these factors can increase a person's risk, they do not necessarily
cause the disease. Some people with one or more risk factors never develop the
disease, while others develop disease and have no known risk factors.
But, knowing your risk factors to any disease can help to guide you into the
appropriate actions, including changing behaviors and being clinically monitored
for the disease.
Screening Guidelines for Colorectal Cancer
Colorectal cancer screening guidelines from the American Cancer Society for
early detection are:
- Beginning at age 50, both men and women should follow this testing schedule:
- Digital rectal examination should be performed at the time of each screening
sigmoidoscopy, colonoscopy, or barium enema examination.
- Yearly fecal occult blood test, plus...
- flexible sigmoidoscopy every 5 years, or
colonoscopy every 10 years, or
double contrast barium enema every 5-10 years
- People with any of the following colorectal cancer risk factors should begin
screening procedures at an earlier age:
- strong family history of colorectal cancer or polyps (cancer or polyps
in a first degree relative younger than 60 or in two first degree relatives
of any age)
- family with hereditary colorectal cancer syndromes (familial adenomatous
polyposis and hereditary non-polyposis colon cancer)
- personal history of colorectal cancer or adenomatous polyps
- personal history of chronic inflammatory bowel disease
This page was last updated on: January 24, 2008.
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