The colon and the rectum—the two parts of the large intestine—are common places for cancer to occur. It is often a hidden cancer because it doesn't usually cause symptoms in its early stages.
Colon cancer affects men and women equally, usually after age 50. That's why experts recommend that adults be tested regularly for colorectal cancer after age 50. Testing is especially important for individuals who are at increased risk for developing colorectal cancer. That include those who: have had polyps (a benign growth in the colon or rectum); have a close family member with colorectal cancer; have ulcerative colitis or Crohn's disease; or who eat a fatty diet or smoke.
Symptoms of colorectal cancer include:
- diarrhea or constipation
- a feeling that the bowel isn't emptying completely
- blood in the stool
- stools that are narrower than usual
- frequently feeling full or bloated
- weight loss with no known reason
There are several ways to check for hidden colorectal cancer. The most effective test is the colonoscopy. In this test, a thin, flexible tube with a camera on the end is passed through the anus and up through the rectum and colon. Any precancerous polyps can be removed during the test. A sigmoidoscopy uses a similar tube, but it is able to look into only the lower portion of the colon. A third test, the fecal occult stool test, can be done at home. It checks for blood in the stool, which can be a sign of bleeding from a colorectal polyp or cancer.
Treatments for colorectal cancer include surgery, chemotherapy, radiation, or a combination of these.
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After a negative colonoscopy at age 50, less invasive screening tests may be just as accurate, but carry less expense and risk for complications, than repeating the colonoscopy every 10 years.
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Colorectal cancer is the third most common cancer among men and
women. Several tests can find hidden colorectal cancer while it
is still small and treatable. These include colonoscopy, flexible
sigmoidoscopy, CT colonography, fecal occult blood test, and
others. Testing should generally start at age 50, but women (and
men) with a strong family history of colorectal cancer should
talk with their doctors about having their first colonoscopy
sooner than that. It's best to have a colonoscopy once every 10
years; a virtual colonoscopy, flexible sigmoidoscopy, or
double-contrast barium enema once every five years; or a stool
check for blood once a year.
Flexible sigmoidoscopy, which is less invasive than full colonoscopy and easier to prep for, every three to five years reduces the risk of developing colorectal cancer later in life.
Preparation for a colonoscopy involves taking a substance the day before the procedure that induces bowel-clearing diarrhea. It's unpleasant and takes several hours, but adequate preparation can make the process somewhat easier to endure.