This section enables you to easily access the
following information:
What is colorectal cancer?
Colorectal cancer is cancer of the
colon and/or
rectum, which are parts of the
digestive system. The digestive system is also called the gastrointestinal, or GI, system. The body
uses the digestive system to turn food products into energy. What the body cannot
use is removed as solid waste matter through bowel movements (fecal matter or stool).
Colorectal cancer happens when cells in the colon
and/or
rectum grow out of control and lose their normal function.
Anatomy of the colon and rectum
The colon is made up of four sections:
- The ascending colon starts where the small intestine attaches to the colon and goes
up the right side of the abdomen.
- The transverse colon crosses from the right to the left side of the body.
- The descending colon goes down the left side of the abdomen.
- The sigmoid colon joins the rectum, which ends at the anus.
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How common is colorectal cancer?
Colorectal cancer is the fourth most common cancer
diagnosed in men and women in the United States. According to the American Cancer
Society, over 145,000 people in the United States will find out that they have colorectal
cancer in 2005.
Colorectal Cancer Incidence - Estimates for new cases in 2005:
|
Colon cancer |
Rectal cancer
|
- Total: 104,950
- Men: 48,290
- Women: 56,660
|
- Total: 40,340
- Men: 25,530
- Women: 16,810
|
Estimated deaths from colorectal cancer in 2005:
- Total: 56,290
- Men: 28,540
- Women: 27,750
The overall number of deaths from colorectal cancer has been decreasing over the
past 15 years. This may be due to the following reasons:
- The number of new colorectal cancer cases has been declining over the past 10 years.
- Successful screening
for colorectal cancer allows for earlier detection and treatment of polyps before
cancer develops. Colorectal cancer is easier to cure the earlier it is found.
- Colorectal cancer treatments have improved.
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How does colorectal cancer develop?
It usually takes many years for colorectal cancer
to develop. It often starts as a polyp (a growth
of tissue) in the colon or rectum. The polyp may
eventually change into a colorectal cancer tumor
(a lump containing cells that are growing out of control). This means the
polyp has become cancerous.
A polyp that is found early can be surgically
removed, but a colorectal cancer
polyp can grow quickly. The tumor can spread, or
metastasize, to other parts of the body.
The types of polyps that are most likely to become
cancerous are called adenomatous polyps, or adenomas.
More than 95% of colorectal cancers are adenocarcinomas,
which are cancers of the glandular cells that
line the inside layer of the colon and rectum walls.
Learn more about the signs and symptoms of
colorectal cancer.
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