There are different colon cancer screening tests that have advantages and disadvantages. None have proven to be better than colonoscopy, but they can be used as alternative screening techniques. Whether or not they replace colonoscopy is a discussion you need to have with your doctor.

If a doctor suspects that you may have colorectal cancer, he or she will examine you to look for a lump in your abdomen, anemia, or other warning signs of colon cancer. The examination will usually include a digital rectal examination. This is where a doctor inserts a gloved finger through your anus into your rectum to feel if there is a tumor in the lower part of the rectum. However, this particular exam is not very sensitive, and it may not detect cancer when the disease is in it's early stages. Therefore, your doctor may recommend additional testing using one or more of the screening methods for colorectal cancer outlined in Key Point 1.

Pros and Cons of Different Types of Colorectal Exams

There are pros and cons associated with each of the various tests that are used to screen for colorectal cancer.  Talk with your doctor about which is best for you.

Fecal occult blood test

• Pros
• Not complex
• Can be done at home
• Noninvasive, low risk
• Inexpensive*
• Cons
• Patient may have to avoid some foods and medicines before and until stool samples are collected
• Patient may find the task disagreeable and not adhere to completing all tests
• Better for identifying cancers than pre-cancerous polyps; however, blood must be present to identify a problem
• If blood is found, follow-up testing is needed

Flexible sigmoidoscopy

• Pros
• Increases the chance of finding polyps and early cancers versus the fecal occult blood test
• May be performed in a primary care doctor's office
• Moderate cost*
• Cons
• Cannot examine entire colon
• Patient will have to restrict diet and use laxatives and/or enemas to clean out the colon and rectum
• Invasive with very slight risk of perforation, infection, bleeding
• Patient may experience some discomfort during or after exam (sedation is rarely used for test)
• If polyps or lesions are found, a follow-up procedure is needed

Colonoscopy
(Colonoscopy is usually recommended as a follow-up test if any of the other screening tests are abnormal.)

• Pros
• Full colon visualization
• Doctor will be able to identify polyps, which also can be removed during the test so only one bowel preparation is necessary
• Sedation is used so the patient doesn't experience discomfort during the test
• Cons
• Patient will have to restrict diet and use laxatives and/or enemas to clean out the colon and rectum
• There are risks association with sedation
• Invasive with slight risk of perforation, infection, bleeding
• Patient may experience some discomfort after exam
• Patient is advised not to drive or work on the day of the exam due to sedation
• Most expensive*

Double Contrast Barium Enema

• Pros
• Provides full colon visualization
• Fairly good percentage of polyps and cancers can be detected at approximately 50 to 80 percent of polyps less than 1 cm in size, 70 to 90 percent of polyps larger than 1 cm and 50 to 80 percent of stage I and II adenocarcinomas
• Low risk
• Less expensive than colonoscopy*
• Cons
• Before the test, your doctor will recommend that you restrict your diet and use laxatives and/or enemas to clean out your colon and rectum.
• Patient may feel discomfort during or after exam.
• If polyps or lesions are found, a follow-up procedure is needed
• The efficacy of barium enema in preventing deaths from colorectal cancer has not been evaluated in a controlled trial.

*Note:  The cost of individual screening tests vary, but the cost of lifetime programs of screening and follow-up of abnormal test results are comparable per year of life saved (assuming that screening begins at the age of 50 years and is discontinued at the age of 85 years).