| 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
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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 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 often 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.
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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. |
- ulcerative colitis
People who have ulcerative colitis, an 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 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 examined.
- 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.
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
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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.
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