Screening and Surveillance for Colorectal Cancer
What is the risk of colorectal cancer?
Colorectal cancer is the fourth most common non-skin cancer, affecting all ethnic groups. About 140,000 people will be diagnosed with colorectal cancer each year and more than 50,000 will die; the lifetime risk is 1 in 20 (5%). An increased risk of developing colorectal cancer is present if there is a personal or family history of colorectal cancer. A personal history of breast, uterine, or ovarian cancer also increases one's risk of developing colorectal cancer. A personal or family history of colonic polyps also increases that risk. Both Crohn's disease and ulcerative colitis may make colorectal cancer more likely after having the disease for a number of years.
Why should people be screened?
Colorectal cancer rarely causes symptoms in its early stages. Colon cancer usually starts out as a benign polyp. Colon polypscan be both precancerous and non-precancerous. Polyps can be detected by screening tests and can be removed, thus preventing colorectal cancer. early cancers can be cured and up to 90% of cases. Once colorectal cancer causes bleeding, change in bowel habits, or abdominal pain, it has usually progressed to a more advanced stage where less than 50% of patients are cured.
What screening tests are available?
Fecal occult blood testing checks several stool samples for invisible amounts of blood from a colorectal polyp for cancer. If it is positive, a colonoscopy (see below) is needed.
Colonoscopy uses a long, flexible instrument to evaluate the lining of the colon and rectum. Abnormal areas may be sampled or removed and sent to the lab for testing. Safe and effective, colonoscopy is the most commonly recommended screening test, because the whole corn is seen and precancerous polyps can be removed, preventing colon cancer. Colonoscopy is the "gold standard" for colorectal cancer screening.
Flexible sigmoidoscopy allows a physician to look at the lower third of the colon,where about half of all polyps and cancers are found. If an abnormality is found, a colonoscopy is then needed. Fecal occult blood testing and flexible sigmoidoscopy are often combined for colorectal cancer screening. However, colonoscopy is considered the optimal method of screening when the test is available and there is no medical contraindication.
An air contrast barium enema is an X-ray test in which the colon is filled with air and dye to make a lining visible. It is mostly used only if a complete colonoscopy cannot be done.
Virtual colonoscopy combines CT scan images of the air-filled colon into pictures that look like a colonoscopy. If abnormalities are found, colonoscopy is then necessary. It is also useful in patients who have an incomplete colonoscopy. However, most insurance plans as well as Medicare may not cover this procedure.
What are the screening recommendations?
For people with no risk factors, screening starts at age 45. Having a colonoscopy every 8 to 10 years is considered the gold standard. Flexible sigmoidoscopy every 5 years with yearly stool occult blood testing is an acceptable alternative when a colonoscopy is not feasible. People with a close relative (parent or sibling) with colorectal cancer or polyps will start screening at age 40, or 10 years before the youngest age at which a relative was diagnosed. These patients will often undergo screening every three to five years, even if their test is normal. Less common types of inherited colon cancer (hereditary non-polyposis)may require much more frequent screening, beginning at an earlier age.
What are the surveillance recommendations?
People who have precancerous polyps completely removed should have a colonoscopy every 3 to 5 years, depending on the size, type, and number of polyps found. The exam interval will usually depend upon the pathology of the growth removed. If a polyp is not completely removed by colonoscopy or surgery, another colonoscopy should be done in 3 to 6 months. Most colorectal cancer patients should have a colonoscopy within one year of its initial removal. If the whole: could not be examined prior to surgery, then colonoscopy should be done within 3 to 6 months. If this first surveillance is normal, then colonoscopy should be done every three to five years. Patients with ulcerative colitis or Crohn's disease for 8 or more years should have a colonoscopy with multiple biopsies every 1 to 2 years.
Colonoscopy
Colonoscopy is an effective procedure to diagnose abnormalities of the large intestine and to screen for colorectal cancer and colorectal polyps. A colonoscope is a long, thin flexible instrument that provides magnified views of the colon and rectum. The procedure is frequently performed in an outpatient setting with minimal discomfort and inconvenience. Because colonoscopy allows doctors to identify and remove certain types of colon polypsthat may develop into cancer, colonoscopy can be a therapeutic and even life-saving procedure.
Who should have a colonoscopy?
Screening refers to the process of examining otherwise healthy patients in an effort to detect previously undiagnosed colon polyps or cancer. The goal of a screening program is to detect disease at its earliest stages to allow for successful treatment. As part of a colorectal cancer screening program, colonoscopy is routinely recommended to adults starting at age 45. Patients who have a family history of colon or rectal cancer or polyps may be recommended for a colonoscopy earlier and more frequently than those without a family history of cancer. Your doctor may also recommend a colonoscopy to evaluate symptoms such as rectal bleeding, a change in bowel habits, or unexplained abdominal pains.
Colonoscopy may also be recommended for:
- Follow-up examinations for patients who have a personal history of colon or rectal polyps or cancer
- patients with acute or chronic anemia
- patients with inflammatory bowel disease (e.g.,Crohn's disease or ulcerative colitis)
- patients with certain familial hereditary conditions such as hereditary nonpolyposis colorectal cancer (also known as Lynch syndrome)
How is a colonoscopy performed?
One or two days prior to the procedure, most patients must complete a bowel "prep" -a prescribed preparation consisting of liquids that will cleanse the bowels of stool and other residue. This allows for complete visualization of the bowel surface during the procedure. Your doctor will most likely give you a list of dietary and medication restrictions to follow in the days leading up to the procedure. The most important part of the procedure is your completion of the cleansing process as requested by your physician. If you have any questions at all, do not hesitate to discuss your concerns with your physician before the day of the procedure. During the colonoscopy, most patients receive intravenous sedation. 1 or more medications are administered to help patients remain comfortable for the duration of the procedure. The colonoscopeis inserted via the rectum and advanced to the first portion of the colon,where it is connected to the end of the small intestine. Any polyps or other abnormalities encountered during the colonoscopy will be removed and/orbiopsied and sent for analysis. For most patients, the entire procedure takes less than an hour. After the colonoscopy is completed some patients may experience slight discomfort in the form of abdominal cramping and "gas pains", this is quickly resolved by passing any gas/ air that was insufflated during the procedure. In many cases, patients do not recall specifics of the procedure itself due to the situation. It is always important to have the individual who will be taking you home be there to discuss the discharge instructions with the physician and nurse before discharge. Following colonoscopy,patients usually resume their regular diet. Resumption of your pre-procedure medications will be determined by your physician. Some restrictions for driving and activity levels apply when intravenous sedation medications are given to sedate patients immediately prior to colonoscopy. These medications affect judgment and coordination for variable amounts of time following the procedure. Most patients are able to resume normal activity the morning following the colonoscopy.
What are the benefits of colonoscopy?
Colonoscopy is the recommended means of colorectal cancer screening. The procedure allows for detection and removal of colon polyps that are prone to transform into cancer.
What are the risks of colonoscopy?
Colonoscopy is a very safe procedure with few complications, occurring in less than 1% of patients. Infrequent risks include bleeding, perforation (a tear in the intestine), rare side effects from sedation medicine, and inability to visualize the entire colon for polyps or other conditions. For anatomical reasons your physician may deem it unsafe to complete the colonoscopy and will therefore terminate the examination. In such instances, your physician will discuss with you whether or not additional or alternative examinations are indicated.
