Colorectal cancer is a disease in which malignant (cancer) cells form in the tissues of the colon or the rectum.
Colorectal cancer is the third leading cause of death from cancer in the United States.
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).
Race
Black individuals have an increased risk of colorectal cancer and death from colorectal cancer compared to other races.
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.
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If you care about Colon cancer, please read studies about whether aspirin could lower colon cancer risk in older people, and findings of drug that may lower death risk in colon cancer.
For more information about colon health, please see recent studies about how to protect yourself from colon cancer, and results showing this vitamin level in the body linked to colon cancer risk.
