Screening for Colon and Rectal Cancer
Screening for colon and rectal cancer can detect precancerous polyps, which can be present in the colon for up to 10 years before invasive cancer develops. The Center for Disease Control reports that when colon cancer is found early through screening and treated promptly, the 5-year relative survival rate is 90 percent.
Risk Factors for Colon and Rectal Cancer
The screenings your doctor recommends will depend heavily on your risk factors for developing colon and rectal cancer. Keep in mind that having one or more risk factors does not mean you will definitely get the disease, and having no risk factors does not mean you cannot get it.
Studies have linked several factors to the risk for colon cancer:
It’s important that both you and your doctor are aware of any factors that could increase your risk of developing colon cancer.
Digital Rectal Exam
A digital rectal exam is often part of a routine physical examination. Your doctor inserts a lubricated, gloved finger into your rectum to feel for abnormalities. If he or she finds anything unusual, additional screening tests may be performed.
For this test, your doctor will ask you to submit a sample of your stool so that it can be examined by the lab. How the sample is collected depends on the specific type of FOBT your doctor wants the lab to perform, so make sure to get specific instructions before you leave the office.
Currently, two types of FOBT are available:
In a sigmoidoscopy, your doctor inserts a flexible, lighted instrument called a sigmoidoscope into your rectum and lower colon to look for signs of polyps or cancerous tissue.
When you schedule your exam, you’ll be given instructions on how to prepare for it. This usually includes using an enema to empty your bowels about one hour before the sigmoidoscopy. On the morning of the procedure, you’ll want to eat a light breakfast.
The test usually takes 10–20 minutes; while you may experience some discomfort, this is usually temporary.
A colonoscopy is similar to a sigmoidoscopy, except that a sigmoidoscopy only lets your doctor see the lower (descending) colon, while a colonoscopy lets him or her examine the entire colon. Like in a sigmoidoscopy, your doctor can pass very small tools through the colonoscope to take cells for a biopsy or to burn off polyps.
Preparing for your colonoscopy will take 1–2 days, depending on the type of prep recommended to you. The goal of the prep is to make sure your colon is empty for the test, so you’ll need to forego solid foods and take a solution that triggers bowel-clearing activity. During your prep days, you’ll want to stay home since you will need to use the bathroom often. Since you’ll be sedated for the test, you’ll want to have someone drive you to and from the hospital or clinic on the day of the procedure.
Because a colonoscopy goes deeper into the colon, you may be given pain medication and a sedative before the procedure to help you relax. You may feel sleepy during the test and may not remember much afterwards.
After the exam, you will stay in the hospital or clinic for 1–2 hours until the sedative wears off. You may receive the results before you leave, or your doctor may schedule a follow-up appointment.
Most people have no problems after a colonoscopy, but you should contact your physician if you notice heavy bleeding from your anus, abdominal swelling or pain, or if you feel sick or have a fever.
Virtual Colonoscopy (Computerized Tomographic Colonography)
A virtual colonoscopy uses computerized tomography (CT) to take multiple images of your abdominal organs. A computer is then used to assemble these images into a detailed view of the colon and rectum. Because it’s less invasive than a traditional colonoscopy, it usually requires no sedation, and it only takes about 10 minutes.
After the exam, most of the air will be removed from your colon through the catheter, and you may feel bloated or pass gas for a few hours afterward until the rest of the air is cleared. Walking may help relieve any discomfort, and you can return to your usual diet and activities right away. Consult your doctor if your symptoms don't improve on their own.
As with a colonoscopy, your colon will need to be empty for the DCBE to be effective. Your physician will give you specific instructions on preparing for the test, which may involve taking laxatives and/or taking an enema the morning of the exam. You will also be asked to follow a clear liquid diet for 1–2 days before the procedure.
If polyps or other suspicious areas are seen on this test, a colonoscopy will likely be needed to remove them or to explore them fully.
To learn more about colon cancer screening at the Methodist Cancer Center, please call us at 713-790-2700.