Colon and rectal cancer
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Risk factors for colon and rectal cancer

There are many things that can make you more or less likely to get colon or rectal cancer.

Factors that can increase your risk
Your family history
If you have a close relative who has had colon or rectal cancer, your chances of getting the disease are increased.

If no one in your close family has had colon or rectal cancer, your chances of getting this type of cancer are 2 in 100 .
 
 
 
 
 
Source:
Iskowitz SH, Kim YS.
Colonic polyps and polyposis syndromes.
In: Feldman M, Sleisenger MH, Scharschmidt BF. Sleisenger and Fordtrans gastrointestinal and liver disease: pathophysiology, diagnosis, management. 6th edition. Saunders, Philadelphia, U.S.A.; 1998.
 
 
 
 
 
1 This means that 1 in 50 Americans who have no relatives with colon or rectal cancer will get the disease.

But if one of your parents, a brother, a sister or a child has had colon or rectal cancer, your risk increases to about 1 in 17. The more relatives you have with the disease, the bigger your risk becomes.
 
 
 
 
 
Source:
Iskowitz SH, Kim YS.
Colonic polyps and polyposis syndromes.
In: Feldman M, Sleisenger MH, Scharschmidt BF. Sleisenger and Fordtrans gastrointestinal and liver disease: pathophysiology, diagnosis, management. 6th edition. Saunders, Philadelphia, U.S.A.; 1998.
 
 
 
 
 
1 And if you have a close relative who was younger than 45 when diagnosed with colon or rectal cancer, your risk moves to 1 in 10.

Some inherited conditions can lead to colon and rectal cancer. (When a condition is inherited, this means that it can be passed on from parent to child.) Two particularly important ones are familial adenomatous polyposis (FAP for short) and hereditary nonpolyposis colorectal cancer (HNPCC for short). See Inherited conditions that can lead to colon and rectal cancer.

Getting older
Your chances of getting colon or rectal cancer increase as you get older, especially after you've reached age 50. About 9 in 10 people who have colon or rectal cancer are over 50.
 
 
 
 
 
Source:
American Cancer Society.
Colorectal cancer facts and figures: special edition 2005.
Available at http://www.cancer.org (accessed on 6 May 2009).
 
 
 
 
 
2

What you eat
Scientists have found that colon and rectal cancer is more common in the United States and other developed countries than in undeveloped countries. They think the reason may be a high-calorie diet, especially one that's rich in meat, fat and oil.
 
 
 
 
 
Source:
Mayer RJ.
Gastrointestinal tract cancer.
In: Braunwald E, Hauser SL, Fauci AS, et al. Harrison's principles of internal medicine. McGraw-Hill, New York, U.S.A.; 2001.
 
 
 
 
 
3 The type of fat seems to be important. A diet rich in animal fat and red meat (but not vegetable fat) seems to increase the risk of colon and rectal cancer. However, fish oils may protect you from this cancer.
 
 
 
 
 
Source:
Skibber JM, Minsky BD, Hoff PM.
Cancer of the colon.
In: DeVita VT Jr, Hellman S, Rosenberg SA (editors). Cancer of the colon. 6th edition. Lippincott Williams and Wilkins, Philadelphia, U.S.A.; 2001.
 
 
 
 
 
4

The role of
 
 
 
 
 
fiber
Fiber is all the parts of your diet that your body can't absorb. This is why foods that are high in fiber make you have more bowel movements. When your body can't absorb something, it leaves your body in your stools. Foods high in fiber include wholemeal bread and cereals, root vegetables and fruits.
 
 
 
 
 
fiber in the development of colon and rectal cancer is less clear. Scientists used to think that eating fiber protected you from this disease. They thought it helped move waste (
 
 
 
 
 
feces
Feces are also called stools or bowel movements. They contain what is left over from the food you have eaten and other things that your body wants to get rid of.
 
 
 
 
 
feces) through the colon and rectum more quickly. This meant that possibly harmful materials in the feces were in contact with intestine wall for less time. But this theory has been dropped. Eating more fiber has not been shown to speed up the passage of feces.
 
 
 
 
 
Source:
Mayer RJ.
Gastrointestinal tract cancer.
In: Braunwald E, Hauser SL, Fauci AS, et al. Harrison's principles of internal medicine. McGraw-Hill, New York, U.S.A.; 2001.
 
 
 
 
 
3

Other diseases
If you have an inflammatory disease of your bowels, you're more likely to get colon or rectal cancer. These diseases include
 
 
 
 
 
ulcerative colitis
Ulcerative colitis is a disease that affects the wall of your large intestine. Ulcerative colitis causes you to have diarrhea and get blood in your stools. Ulcerative colitis is an autoimmune disease. This means that you get it when your body attacks part of itself.
 
 
 
 
 
ulcerative colitis and
 
 
 
 
 
Crohn's disease
Crohn's disease causes iflammation in your bowel. It usually affects your small intestine, but can happen anywhere in your digestive tract. It causes diarrhea and bloody stools.
 
 
 
 
 
Crohn's disease. Also, the longer you have one of these diseases, the greater your risk of getting colon or rectal cancer. Research shows that up to a third of people who've had one of these diseases for more than 25 years will get colon or rectal cancer.
 
 
 
 
 
Source:
Mayer RJ.
Gastrointestinal tract cancer.
In: Braunwald E, Hauser SL, Fauci AS, et al. Harrison's principles of internal medicine. McGraw-Hill, New York, U.S.A.; 2001.
 
 
 
 
 
3 The reason for this is unclear.

Smoking
Smoking can increase your risk, especially if you've smoked for more than 35 years. No one knows how smoking makes you more likely to get this cancer.
 
 
 
 
 
Source:
Mayer RJ.
Gastrointestinal tract cancer.
In: Braunwald E, Hauser SL, Fauci AS, et al. Harrison's principles of internal medicine. McGraw-Hill, New York, U.S.A.; 2001.
 
 
 
 
 
3

Other factors
Drinking alcohol every day can increase your risk of getting colon or rectal cancer, but no one knows why. You may also be more at risk if you're overweight, especially if you carry your extra weight around your middle. However, regular exercise and eating less may protect you against this cancer.
 
 
 
 
 
Source:
Skibber JM, Minsky BD, Hoff PM.
Cancer of the colon.
In: DeVita VT Jr, Hellman S, Rosenberg SA (editors). Cancer of the colon. 6th edition. Lippincott Williams and Wilkins, Philadelphia, U.S.A.; 2001.
 
 
 
 
 
4

Factors that can decrease your risk
Hormone replacement therapy
Some women take hormone replacement therapy (or HRT for short) during menopause to help their hot flashes and other symptoms. HRT may also reduce your risk of colon and rectal cancer, although this lowered risk disappears five years after you stop the treatment.
 
 
 
 
 
Source:
Skibber JM, Minsky BD, Hoff PM.
Cancer of the colon.
In: DeVita VT Jr, Hellman S, Rosenberg SA (editors). Cancer of the colon. 6th edition. Lippincott Williams and Wilkins, Philadelphia, U.S.A.; 2001.
 
 
 
 
 
4 However, HRT also increases the risk of getting some conditions, including breast cancer and heart disease. To learn more about these risks, see HRT in our section on menopause.

Birth-control pills
Taking birth-control pills also seems to offer some protection against colon and rectal cancer.
 
 
 
 
 
Source:
Skibber JM, Minsky BD, Hoff PM.
Cancer of the colon.
In: DeVita VT Jr, Hellman S, Rosenberg SA (editors). Cancer of the colon. 6th edition. Lippincott Williams and Wilkins, Philadelphia, U.S.A.; 2001.
 
 
 
 
 
4

NSAIDs and aspirin can also cause stomach
 
 
 
 
 
ulcer
An ulcer is an open sore. Ulcers can happen in many parts of your body, such as in your stomach, and the skin of your legs, mouth or genitals.
 
 
 
 
 
ulcers if taken for a long time. For these reasons, doctors do not yet recommend taking aspirin or other NSAIDs to prevent colon and rectal cancer.

Aspirin and other NSAIDs
There is some evidence that aspirin and other
 
 
 
 
 
NSAIDs
NSAID stands for nonsteroidal anti-inflammatory drug. NSAIDs help with pain, inflammation and fever. They are called 'nonsteroidal' because they don't contain any steroids. Aspirin and ibuprofen are both NSAIDs.
 
 
 
 
 
nonsteroidal anti-inflammatory drugs (NSAIDs) might protect you from colon and rectal cancer.
 
 
 
 
 
Source:
Skibber JM, Minsky BD, Hoff PM.
Cancer of the colon.
In: DeVita VT Jr, Hellman S, Rosenberg SA (editors). Cancer of the colon. 6th edition. Lippincott Williams and Wilkins, Philadelphia, U.S.A.; 2001.
 
 
 
 
 
4 However, some of these drugs have been linked with serious side effects. If you take an NSAID for a long time, it may slightly increase your risk of a heart attack or a stroke. This risk doesn't apply for aspirin. To learn more see Warnings about side effects of NSAIDs.

NSAIDs and aspirin can also cause stomach
 
 
 
 
 
ulcer
An ulcer is an open sore. Ulcers can happen in many parts of your body, such as in your stomach, and the skin of your legs, mouth or genitals.
 
 
 
 
 
ulcers if taken for a long time. For these reasons, doctors do not yet recommend taking aspirin or other NSAIDs to prevent colon and rectal cancer.

Sources for the information on this page:
  1. Iskowitz SH, Kim YS.Colonic polyps and polyposis syndromes.In: Feldman M, Sleisenger MH, Scharschmidt BF. Sleisenger and Fordtrans gastrointestinal and liver disease: pathophysiology, diagnosis, management. 6th edition. Saunders, Philadelphia, U.S.A.; 1998.
  2. American Cancer Society.Colorectal cancer facts and figures: special edition 2005.Available at http://www.cancer.org (accessed on 6 May 2009).
  3. Mayer RJ.Gastrointestinal tract cancer.In: Braunwald E, Hauser SL, Fauci AS, et al. Harrison's principles of internal medicine. McGraw-Hill, New York, U.S.A.; 2001.
  4. Skibber JM, Minsky BD, Hoff PM.Cancer of the colon.In: DeVita VT Jr, Hellman S, Rosenberg SA (editors). Cancer of the colon. 6th edition. Lippincott Williams and Wilkins, Philadelphia, U.S.A.; 2001.
This information was last updated on May 08, 2009
BMJ Group
This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment.
© BMJ Publishing Group Limited 2009. All rights reserved.