Colon Cancer Causes
Most colorectal cancers arise from adenomatous polyps—clusters of abnormal cells in the glands covering the inner wall of the colon. Over time, these abnormal growths enlarge and ultimately degenerate to become adenocarcinomas.
People with any of several conditions known as adenomatous polyposis syndromes have a greater-than-normal risk of colorectal cancer.
In these conditions, numerous adenomatous polyps develop in the colon, ultimately leading to colon cancer.
The cancer usually occurs before age 40 years.
Adenomatous polyposis syndromes tend to run in families. Such cases are referred to as familial adenomatous polyposis (FAP). Celecoxib (Celebrex) has been FDA approved for FAP. After 6 months, celecoxib reduced the mean number of rectal and colon polyps by 28% compared to placebo (sugar pill) 5%.
Colon Cancer Symptoms
Cancer of the colon and rectum can exhibit itself in several ways. If you have any of these symptoms, seek immediate medical help.
You may notice bleeding from your rectum or blood mixed with your stool.
People commonly attribute all rectal bleeding to hemorrhoids, thus preventing early diagnosis owing to lack of concern over "bleeding hemorrhoids."
Rectal bleeding may be hidden and chronic and may show up as an iron deficiency anemia.
It may be associated with fatigue and pale skin.
It usually, but not always, can be detected through a fecal occult (hidden) blood test, in which samples of stool are submitted to a lab for detection of blood.
If the tumor gets large enough, it may completely or partially block your colon. You may notice the following symptoms of bowel obstruction:
Abdominal distension: Your belly sticks out more than it did before without weight gain.
Abdominal pain: This is rare in colon cancer. One cause is tearing (perforation) of the bowel. Leaking of bowel contents into the pelvis can cause inflammation (peritonitis) and infection.
Unexplained, persistent nausea or vomiting
Unexplained weight loss
Change in frequency or character of stool (bowel movements)
Small-caliber (narrow) or ribbon-like stools
Sensation of incomplete evacuation after a bowel movement
Rectal pain: Pain rarely occurs with colon cancer and usually indicates a bulky tumor in the rectum that may invade surrounding tissue.
Studies suggest that the average duration of symptoms (from onset to diagnosis) is 14 weeks. There is no association between overall duration of symptoms and the stage of your tumor.
Prevention
Your best prevention is to detect colon cancer and treat it early in its formation. People who have regular screening for colon cancer, including fecal occult blood tests, sigmoidoscopy or colonoscopy, and polyp removal, greatly reduce their risk of having a colorectal cancer.
Other things you can do to lower your risk include the following:
Quit smoking. Smoking cigarettes has been clearly linked with higher risk of colon cancer (as well as many other conditions).
Take an aspirin or baby aspirin every day. Because of potential side effects, this is not recommended for everyone. Talk to your health care provider first.
Take a safe dose of folic acid (for example, 1 mg) every day.
Engage in physical activity every day.
Eat a variety of fruits and vegetables every day.
The US Agency for Health Care Policy and Research recommends screening for colon cancer in people older than 50 years who have an average risk for the disease and in people aged 40 years and older who have a family history of colorectal cancer. The agency recommends that one of the following screening techniques be used:
Fecal occult blood testing every year combined with flexible sigmoidoscopy every 5 years
Double-contrast barium enema every 5-10 years
Colonoscopy every 10 years: Colonoscopy remains the most sensitive test for detecting colon polyps and tumors.
Once polyps have been identified, they should be removed. After you have had polyps, even one polyp, you should begin to have more frequent colonoscopies.
Appropriate preventive screening for people with ulcerative colitis includes the following:
Colonoscopy every 1-2 years in the following cases:
If you have known you have the disease for 7-8 years
If the cancer involves the entire colon
Beginning 12-15 years after the diagnosis of left-sided colitis
Random colon biopsies taken during colonoscopy
People with ulcerative colitis in whom biopsies show premalignant changes should undergo surgical removal of their colons.
Outlook
Recovery from colon cancer depends on the extent of your disease before your surgery.
If your tumor is limited to the inner layers of your colon, you can expect to live 5 years or more.
If cancer has spread to your lymph nodes adjacent to the colon, the chance of living 5 years is 65%.
If the cancer has already spread to other organs, the chance of living 5 years drops to 8%.
If the cancer has reached your liver but no other organs, removing part of your liver may prolong your life.
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