Colorectal cancer affects men and women of all racial and ethnic groups, and is most often found in people aged 50 years or older. In the United States, it is the third most common cancer for men and women.
Of cancers that affect both men and women, colorectal cancer is the second leading cancer killer in the United States, but it doesn’t have to be. Colorectal cancer screening saves lives.
Screening can find precancerous polyps — abnormal growths in the colon or rectum — so that they can be removed before turning into cancer. Screening also helps find colorectal cancer at an early stage, when treatment often leads to a cure. About nine out of every 10 people whose colorectal cancers are found early and treated appropriately are still alive five years later.
Colorectal cancer is cancer that occurs in the colon or rectum. Sometimes it is called colon cancer, for short. The rectum is the passageway that connects the colon to the anus.
Several screening tests can be used to find polyps or colorectal cancer. The U.S. Preventive Services Task Force recommends colorectal cancer screening for men and women aged 50 to 75 using high-sensitivity fecal occult blood testing (FOBT), sigmoidoscopy, or colonoscopy. (The decision to be screened after age 75 should be made on an individual basis. If you are older than 75, ask your doctor if you should be screened.)
There is no single “best test” for any person. Each test has advantages and disadvantages. Talk to your doctor about the pros and cons of each test, and how often to be tested. Which test to use depends on —
If you are aged 50 or older, get screened now. If you think you may be at higher than average risk for colorectal cancer, speak with your doctor about getting screened early.
Your risk of harm from a colonoscopy increases with age. The older you are or the more medical conditions you have, the more chance you may be harmed by the procedure. Approximately 25 patients in the U.S. out of 10,000 who receive a colonoscopy have some form of minor or major harm, an adverse event as a result. The greatest risk of harm is when the physician who performs the colonoscopy perforates (penetrates) the colon. When the physician attempts to remove a precancerous growth (polyp) the risk of a perforation increases. Flexible sigmoidoscopy results in harm for patients in approximately four patients out of 10,000. The FOBT or FIT tests are not invasive, so they do not pose any measurable physical harm. The number of individuals needed to be screened to find one case of colon cancer is 1,250.
The preparation for a colonoscopy requires cleansing the bowel. The medications required the day before your colonoscopy result in frequent visits to the bathroom. This preparation process is the reason some patients prefer to avoid a colonoscopy. A colonoscopy requires sedation or anesthesia. There is a risk for harm as a result of any sedation or anesthesia. Discuss any concerns about these harms or risks with your doctor.
A risk to be considered is the risk of not obtaining one of the colon cancer screening tests after age 50. Avoiding these procedures may result in undiagnosed and untreated colon cancer.
This is similar to flexible sigmoidoscopy, except the doctor uses a longer, thin, flexible, lighted tube to check for polyps or cancer inside the rectum and the entire colon. During the test, the doctor can find and remove most polyps and some cancers. Colonoscopy also is used as a follow-up test if anything unusual is found during one of the other screening tests.
How often: Every ten years
For this test, the doctor puts a short, thin, flexible, lighted tube into your rectum. The doctor checks for polyps or cancer inside the rectum and lower third of the colon.
How often: Every five years with FOBT every three years without FOBT
There are two types of FOBT. One uses the chemical guaiac to detect blood. The other, a fecal immunochemical test (FIT), uses antibodies to detect blood in the stool. You receive a test kit from your health care provider. At home, you use a stick or brush to obtain a small amount of stool. You return the test kit to the doctor or a lab, where the stool samples are checked for the presence of blood.
How often: Once a year
Sometimes abnormal growths, called polyps, form in the colon or rectum. Over time, some polyps may turn into cancer. Screening tests can find polyps so they can be removed before turning into cancer. Screening also helps find colorectal cancer at an early stage, when treatment often leads to a cure.
Other risk factors include having —
Lifestyle factors that may contribute to an increased risk of colorectal cancer include —
What Can I do to Reduce my Risk?
Almost all colorectal cancers begin as precancerous polyps (abnormal growths) in the colon or rectum. Such polyps can be present in the colon for years before invasive cancer develops. They may not cause any symptoms. Colorectal cancer screening can find precancerous polyps so they can be removed before they turn into cancer. In this way, colorectal cancer is prevented. Screening can also find colorectal cancer early, when there is a greater chance that treatment will be most effective and lead to a cure.
Research is underway to find out if changes to your diet can reduce your colorectal cancer risk. Medical experts don’t agree on the role of diet in preventing colorectal cancer, but often recommend a diet low in animal fats and high in fruits, vegetables, and whole grains to reduce the risk of other chronic diseases, such as coronary artery disease and diabetes. This diet also may reduce the risk of colorectal cancer. Also, researchers are examining the role of certain medicines and supplements, including aspirin, calcium, vitamin D, and selenium in preventing colorectal cancer. People may also reduce risk through physical activity, limiting alcohol consumption and avoiding tobacco. Overall, the most effective way to reduce your risk of colorectal cancer is by having regular colorectal cancer screening tests beginning at age 50.
What are the Symptoms of Colon Cancer?
Colorectal polyps and colorectal cancer don’t always cause symptoms, especially at first. Someone could have polyps or colorectal cancer and not know it. That is why getting screened regularly for colorectal cancer is so important. If you have symptoms, they may include —
If you have any of these symptoms, talk to your doctor. They may be caused by something other than cancer. The only way to know what is causing them is to see your doctor.
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