Key Points
                    - Avoiding risk factors and increasing protective factors may help prevent cancer.    - The following risk factors increase the risk of colorectal cancer:         - Age     - Family history of colorectal cancer     - Personal history     - Inherited risk     - Alcohol     - Cigarette smoking     - Obesity        - The following protective factors decrease the risk of colorectal cancer:         - Physical activity     - Aspirin     - Combination hormone replacement therapy      - Polyp removal        - It is not clear if the following affect the risk of colorectal cancer:         - Nonsteroidal anti-inflammatory drugs (NSAIDs) other than aspirin     - Calcium     - Diet        - The following factors do not affect the risk of colorectal cancer:         - Hormone replacement therapy with estrogen only     - Statins        - Cancer prevention clinical trials are used to study ways to prevent cancer.    - New ways to prevent colorectal cancer are being studied in clinical trials.
                
                
                    Avoiding risk factors and increasing protective factors may help prevent cancer.
                    Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
                
                
                    The following risk factors increase the risk of colorectal cancer:
                    Age    The risk of colorectal cancer increases after age 50. Most cases of colorectal cancer are diagnosed after age 50.       Family history of colorectal cancer    Having a parent, brother, sister, or child with colorectal cancer doubles a person's risk of colorectal cancer.       Personal history    Having a personal history of the following conditions increases the risk of colorectal cancer:             - Previous colorectal cancer.     - High-risk adenomas (colorectal polyps that are 1 centimeter or larger in size or that have cells that look abnormal under a microscope).     -  Ovarian cancer.     -  Inflammatory bowel disease (such as ulcerative colitis or Crohn disease).              Inherited risk    The risk of colorectal cancer is increased when certain gene changes linked to familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC or Lynch Syndrome) are inherited.       Alcohol    Drinking 3 or more alcoholic beverages per day increases the risk of colorectal cancer. Drinking alcohol is also linked to the risk of forming large colorectal adenomas (benign tumors).       Cigarette smoking    Cigarette smoking is linked to an increased risk of colorectal cancer and death from colorectal cancer.    Smoking cigarettes is also linked to an increased risk of forming colorectal adenomas. Cigarette smokers who have had surgery to remove colorectal adenomas are at an increased risk for the adenomas to recur (come back).       Obesity     Obesity is linked to an increased risk of colorectal cancer and death from colorectal cancer.
                
                
                    The following protective factors decrease the risk of colorectal cancer:
                    Physical activity    A lifestyle that includes regular physical activity is linked to a decreased risk of colorectal cancer.       Aspirin    Studies have shown that taking aspirin lowers the risk of colorectal cancer and the risk of death from colorectal cancer. The decrease in risk begins 10 to 20 years after patients start taking aspirin.    The possible harms of aspirin use (100 mg or less) daily or every other day include an increased risk of stroke and bleeding in the stomach and intestines. These risks may be greater among the elderly, men, and those with conditions linked to a higher than normal risk of bleeding.       Combination hormone replacement therapy      Studies have shown that combination hormone replacement therapy (HRT) that includes both estrogen and progestin lowers the risk of invasive colorectal cancer in postmenopausal women.     However, in women who take combination HRT and do develop colorectal cancer, the cancer is more likely to be advanced when it is diagnosed and the risk of dying from colorectal cancer is not decreased.    The possible harms of combination HRT include an increased risk of having:            -  Breast cancer.     - Heart disease.     -  Blood clots.              Polyp removal    Most colorectal polyps are adenomas, which may develop into cancer. Removing colorectal polyps that are larger than 1 centimeter (pea-sized) may lower the risk of colorectal cancer. It is not known if removing smaller polyps lowers the risk of colorectal cancer.     The possible harms of polyp removal during colonoscopy or sigmoidoscopy include a tear in the wall of the colon and bleeding.
                
                
                    It is not clear if the following affect the risk of colorectal cancer:
                    Nonsteroidal anti-inflammatory drugs (NSAIDs) other than aspirin    It is not known if the use of nonsteroidal anti-inflammatory drugs or NSAIDs (such as sulindac, celecoxib, naproxen, and ibuprofen) lowers the risk of colorectal cancer.     Studies have shown that taking the nonsteroidal anti-inflammatory drug celecoxib reduces the risk of colorectal adenomas (benign tumors) coming back after they have been removed. It is not clear if this results in a lower risk of colorectal cancer.     Taking sulindac or celecoxib has been shown to reduce the number and size of polyps that form in the colon and rectum of people with familial adenomatous polyposis (FAP). It is not clear if this results in a lower risk of colorectal cancer.    The possible harms of NSAIDs include:            -  Kidney problems.     - Bleeding in the stomach, intestines, or brain.     - Heart problems such as heart attack and congestive heart failure.              Calcium    It is not known if taking calcium supplements lowers the risk of colorectal cancer.        Diet    It is not known if a diet low in fat and meat and high in fiber, fruits, and vegetables lowers the risk of colorectal cancer.     Some studies have shown that a diet high in fat, proteins, calories, and meat increases the risk of colorectal cancer, but other studies have not.
                
                
                    The following factors do not affect the risk of colorectal cancer:
                    Hormone replacement therapy with estrogen only    Hormone replacement therapy with estrogen only does not lower the risk of having invasive colorectal cancer or the risk of dying from colorectal cancer.       Statins    Studies have shown that taking statins (drugs that lower cholesterol) does not increase or decrease the risk of colorectal cancer.
                
                
                    Cancer prevention clinical trials are used to study ways to prevent cancer.
                    Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.     The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include exercising more or quitting smoking or taking certain medicines, vitamins, minerals, or food supplements.
                
                
                    New ways to prevent colorectal cancer are being studied in clinical trials.
                    Clinical trials are taking place in many parts of the country. Information about clinical trials can be found in the Clinical Trials section of the NCI website. Check NCI's list of cancer clinical trials for colon cancer prevention trials or rectal cancer prevention trials that are now accepting patients.