- Home >
- Types of Cancer >
- Colorectal Cancer >
- Colorectal Cancer: Screening
ON THIS PAGE: You will find out more about screening for colorectal cancer. You will also learn the risks and benefits of screening. Use the menu to see other pages. Screening is used to look for cancer before you have any symptoms or signs. Scientists have developed, and continue to develop, tests that can be used to screen a person for specific types of cancer before signs or symptoms appear. The overall goals of cancer screening are to: Lower the number of people who die from the disease, or eliminate deaths from cancer altogether Lower the number of people who develop the disease Learn more about the basics of cancer screening. Colorectal cancer can often be prevented through regular screening, which can find polyps before they become cancerous. Talk with your doctor about when screening should begin based on your age and family history of the disease. People with an average risk should begin screening at age 45. Because colorectal cancer usually does not cause symptoms until the disease is advanced, it is important for people to talk with their doctor about the pros and cons of each screening test and how often each test should be given. Under the guidelines below, people should begin colorectal cancer screening earlier and/or undergo screening more often if they have any of the following risk factors for colorectal cancer: A personal history of colorectal cancer or adenomatous polyps A strong family history of colorectal cancer or polyps, such as cancer or polyps in a first-degree relative younger than 60 or in 2 first-degree relatives of any age. A first-degree relative is defined as a parent, sibling, or child. A personal history of chronic inflammatory bowel disease (IBD) A family history of any hereditary colorectal cancer syndrome, such as familial adenomatous polyposis (FAP), Lynch syndrome, or other syndromes (see Risk Factors and Prevention) The tests used to screen for colorectal cancer are described below. Colonoscopy. A colonoscopy allows the doctor to look inside the entire rectum and colon while a patient is sedated. A flexible, lighted tube called a colonoscope is inserted into the rectum and the entire colon to look for polyps or cancer. During this procedure, a doctor can remove polyps or other tissue for examination (see “Biopsy” in the Diagnosis section). The removal of polyps can also prevent colorectal cancer. Computed tomography (CT or CAT) colonography. CT colonography, sometimes called virtual colonoscopy, is a screening method being studied in some centers. It requires interpretation by a skilled radiologist to provide the best results. A radiologist is a doctor who specializes in obtaining and interpreting medical images. CT colonography may be an alternative for people who cannot have a standard colonoscopy due to the risk of anesthesia, which is medication to block the awareness of pain, or if a person has a blockage in the colon that prevents a full examination. Sigmoidoscopy. A sigmoidoscopy uses a flexible, lighted tube that is inserted into the rectum and lower colon to check for polyps, cancer, and other abnormalities. During this procedure, a doctor can remove polyps or other tissue for later examination. The doctor cannot check the upper part of the colon, the ascending and transverse colon, with this test. This screening test allows for the removal of polyps, which can also prevent colorectal cancer, but if polyps or cancer are found using this test, a colonoscopy to view the entire colon is recommended. Fecal occult blood test (FOBT) and fecal immunochemical test (FIT). A fecal occult blood test is used to find blood in the feces, or stool, which can be a sign of polyps or cancer. A positive test, meaning that blood is found in the feces, can be from causes other than a colon polyp or cancer, including bleeding in the stomach or upper gastrointestinal (GI) tract and even eating rare meat or other foods. There are 2 types of tests: guaiac (FOBT) and immunochemical (FIT). Polyps and cancers do not bleed continually, so FOBT must be done on several stool samples each year and should be repeated every year. Even then, this screening test provides a fairly small reduction in deaths from colorectal cancer, around 30% if done yearly and 18% if done every other year. Double contrast barium enema (DCBE). For patients who cannot have a colonoscopy, an enema containing barium is given, which helps make the colon and rectum stand out on x-rays. A series of x-rays is then taken of the colon and rectum. In general, most doctors would recommend other screening tests because a barium enema is less likely to detect precancerous polyps than a colonoscopy, sigmoidoscopy, or CT colonography.Screening information for colorectal cancer
Stool DNA tests. This test analyzes the DNA from a person’s stool sample to look for cancer. It uses changes in the DNA that occur in polyps and cancers to find out if a colonoscopy should be done.
Colorectal cancer screening recommendations
Different organizations have made different recommendations for colorectal cancer screening. There are 2 sets of recommendations described below. Talk with your doctor about the best test(s) and time between tests based on your health history and personal colorectal cancer risk.
The American Society of Clinical Oncology (ASCO) has developed guidelines for colorectal cancer screening to help prevent cancer for people with an average risk. Beginning at age 50, both men and women with an average risk of colorectal cancer should follow 1 of these testing schedules. People with an average risk do not have a family history of the disease, an inherited syndrome such as Lynch syndrome, or IBD, and they have not been diagnosed with colorectal cancer in the past.
The following tests detect both polyps and cancer:
-
Flexible sigmoidoscopy every 5 years, or every 10 years with FIT or FOBT every year
-
Colonoscopy, every 10 years
-
DCBE, every 5 years
-
CT colonography, as often as your doctor recommends
These tests primarily detect cancer:
-
Guaiac-based FOBT, every year
-
FIT, every year
-
Stool DNA test, as often as your doctor recommends
The U.S. Preventive Services Task Force (USPSTF) also has guidelines for colorectal cancer screening, which do not recommend any specific screening method. Instead, USPSTF simply recommends that people between ages 45 and 75 should receive regular screening.
According to the USPSTF, adults between ages 76 and 85 should talk with their doctor to see if screening is right for them. However, people who have a history of polyps or colorectal cancer have a higher risk of the disease, and screening may still be recommended at an older age.
Access to certain screening services may be limited in rural and other underserved areas. Talk with your health care team about your options nearby, and learn more about ASCO's recommendations for preventing colorectal cancer. For more information on treatment decisions in older patients, read Cancer.Net’s article on this topic.
Due to the rising incidence of colorectal cancer in younger people, the American Cancer Society also recommends that people at average risk of colorectal cancer start regular screening at age 45.
It is important to note that, regardless of which screening test and schedule used, any test that indicates an abnormality should be followed up with a colonoscopy.
The next section in this guide is Symptoms and Signs. It explains what changes or medical problems colorectal cancer can cause. Use the menu to choose a different section to read in this guide.
What Is a Barium Enema?
A barium enema is a type of X-ray imaging test that allows doctors to examine your lower intestinal tract. It involves delivering a contrast solution that contains the metallic element barium into your rectum while a technician takes X-ray images of the area. The barium solution will be delivered using an enema — a process in which your doctor pushes a liquid into your rectum through your anus.
The barium solution helps to improve the quality of the X-ray images by highlighting certain areas of tissue. The X-ray used in this procedure is known as fluoroscopy. It allows the radiologist to see your internal organs in motion by tracking the flow of the barium solution through your intestinal tract.
The test doesn’t require painkillers or sedation, but there may be moments of slight discomfort.
Your doctor may order a barium enema if they suspect an abnormality in your lower gastrointestinal (GI) tract. There are numerous conditions and symptoms that could prompt your doctor to examine your lower GI tract, including:
- abdominal pain
- blood in your stools
- a change in your bowel movements
- Crohn’s disease
- chronic diarrhea
- colorectal cancer
- diverticulitis
- irritable bowel syndrome
- polyps
- rectal bleeding
- a twisted loop of the bowels (volvulus)
- ulcerative colitis
Your doctor will ask you to cleanse your bowels the night before your test. This may include using laxatives or taking an enema at home.
You shouldn’t eat anything after midnight the night before your procedure. On the day of the procedure, you can drink clear liquids, such as water, tea, juice, or broth. This is to ensure that your colon is clear of any stool, which could show up in the X-ray images. Tell your doctor if you’ve been having problems with your bowel movements prior to the test.
A barium enema typically takes between 30 and 60 minutes and is performed at a hospital or specialized testing facility. You’ll change into a hospital gown and remove any jewelry or other metal from your body. Metal can interfere with the X-ray process.
You’ll be positioned on an exam table. X-rays will be taken to ensure that your bowels are clear. This may also involve a physical rectal exam.
The radiologist will then insert a small tube into your rectum and introduce the barium and water mixture. The radiologist may gently push air into your colon after the barium has been delivered in order to allow for even more detailed X-ray images. This is called an air-contrast barium enema.
The technician will instruct you to hold still and hold your breath while the X-ray images are taken. You’ll most likely be repositioned several times to take pictures of your colon from different angles. This may cause you some discomfort and cramping, but it’s typically mild.
If you’re having trouble keeping the solution in your colon, alert the technician.
After the procedure, the majority of the barium and water will be removed through the tube. The rest you’ll pass in the bathroom.
The results are typically categorized as negative or positive. A negative result means that there were no abnormalities found. A positive result means that abnormalities were found. This usually means that further testing will be required.
Your doctor will discuss your results with you and the next steps.
Any test involving radiation carries a slight risk of cancer, including X-rays. However, the benefit of an accurate diagnosis outweighs the risks from the small amount of radiation you’ll be exposed to during the test. Remember that many things you do regularly, such as flying in an airplane, expose you to much more radiation than an X-ray.
If you are pregnant or believe you may be pregnant, tell your doctor. X-rays are not recommended for pregnant women because the radiation could harm your unborn child.
If it’s possible you have a tear, also called a perforation, in your colon, your doctor may opt for a contrast solution with iodine in it. This solution causes fewer potential complications if it leaks out of your colon.
The most common risk of a barium enema is an allergic reaction to the barium solution. Tell your doctor about any allergies you have.
Other rare complications from a barium enema may include:
- inflammation of the tissues around your colon
- obstruction of your gastrointestinal tract
- a perforated colon
- a tear in your colon wall
After the exam you can go about your day as you normally would. You may resume a normal diet but you should drink lots of water and increase your fiber intake. This means increasing how much water you drink and eating foods like whole-wheat pasta, beans, peas, and raspberries. Sometimes a laxative is needed to help remove the barium.
For a few days after the procedure, you may notice that your stools are white or lighter in color than normal. This is caused by the barium and is considered normal. Your rectum and anus may be sore from the procedure.
If you have difficulty or pain with bowel movements, fever, or rectal bleeding, call your doctor. If you do not have a bowel movement for two days after the exam or are unable to pass gas, call your doctor.