Colorectal cancer is the second most common cancer in the United Kingdom. Annually, an estimated 14000 die of the disease. The average person’s lifetime risk of developing it is about one chance in 20. The risk is increased if there is a family history of colorectal polyps or cancer, and is still higher if there is a personal history of breast, uterine or ovarian cancer. Risk is also higher for people with a history of extensive inflammatory bowel disease, such as ulcerative colitis.
What is screening and surveillance?
Many polyps and cancers of the colon and rectum do not produce symptoms until they become fairly large. Screening involves one or more tests performed to identify whether a person with no symptoms has a disease or condition that may lead to colon or rectal cancer. The goal is to identify the potential for disease or the condition early when it is easier to prevent or cure. Surveillance involves testing people who have previously had colorectal cancer or are at increased risk. Because their chance of having cancer is higher, more extensive or more frequent tests are recommended.
Later in this document, the tests and risk groups are defined. Also, your doctor can further explain the tests and their value to you.
Why should testing be undertaken?
Colorectal cancer is known as a “silent” disease, because many people do not develop symptoms, such as bleeding or abdominal pain until cancer is difficult to cure. In fact, the possibility of curing patients after symptoms develop is only about 50%. On the other hand, if colorectal cancer is found and treated at an early stage, before symptoms develop, the opportunity to cure is 80% or better. Most colon cancers start as non-cancerous growths called polyps. If the polyps are removed, then the cancer may be prevented. Major surgery can usually be avoided.
What screening tests should be done?
The simplest screening test for colon and rectal cancer is testing of the stool to detect tiny amounts of invisible blood; this is called faecal occult blood testing. This test has been available for many years, is inexpensive and very simple. Unfortunately, it only detects cancer or polyps, which are bleeding at the time of the test. Only about 50% of cancers and 10% of polyps bleed enough to be detected by this test. Therefore, further screening is necessary for accurate detection of cancers and polyps.
Flexible sigmoidoscopy is a test, which allows the physician to look
directly at the lining of the colon and rectum. During this test, the lining
of the lower one third of the colon and rectum can usually be seen. This is
the portion of the lower intestine, which accounts for most polyps and
cancers. When flexible sigmoidoscopy is combined with testing the stool for
hidden blood, many cancers and polyps can be detected.When a polyp or cancer is detected by flexible sigmoidoscopy, or if a person is at high risk to develop colon and rectal cancer, colonoscopy provides a safe, effective means of visually examining the full lining of the colon and rectum. Colonoscopy is used to diagnose colon and rectal problems and to perform biopsies and remove colon polyps. Most colonoscopies are done on an outpatient basis with minimal inconvenience and discomfort.
A barium enema or x-ray of the colon is almost as good as colonoscopy in
detecting large tumours, but it is not as accurate for small tumours or
polyps. The combination of barium enema and sigmoidoscopy is better than
either test alone, but not as good as colonoscopy. The last sheet describes the protocol for screening/surveillance.
If you would like to participate in the screening/surveillance program, we would recommend that you contact your GP for a referral. You will not need any sedation for the flexible sigmoidoscopy nor will you need to stay in hospital. In other words, you will be a day-surgical patient. We may recommend a test to look for occult or hidden blood in stools.
On the other hand, if you do not wish to have the stool test, please indicate this to your GP so that arrangements can be made for a colonoscopy. We may request a Barium enema, if the colonoscopy is incomplete, which could happen in 30 to 40% of cases.
We hope the enclosed information is helpful to you and do hope that you will comply with the screeing/surveillance program.
Risk category Recommedation** Age to begin Interval LOW RISK All people 50 years or older who are not in the categories below One of the following:
FOBT plus flexible sigmoidoscopy$
Or TCE. Age 50 FOBT every year and flexible sigmoidoscopy every 5 years or TCE if FOBT is positive
Colonoscopy every 10 years or DCBE every 5-10 years. MEDIUM RISK People with <4 small (<2 cm adenomatous) polyps Colonoscopy At time of initial polyp diagnosis TCE at 1 year after initial polyp removal; if normal, as per average risk recommendations (above) People with large (>2 cm) or multiple (>4) polyps of any type Colonoscopy At time of initial polyp diagnosis TCE at 1 year after initial polyp removal; if normal, TCE every 3 years. Personal history of curative-intent resection of colorectal cancer TCE# Within 1 year after resection If normal, TCE in 3 years; if still normal, TCE every 5 years. Colorectal cancer or adenomatous polyps in first degree relative younger than 60 years or in two or more first-degree relatives of any ages TCE Age 40 or 10 years before the youngest case in the family, whichever is earlier. Every 5 years Colorectal cancer in other relatives (not included above) As per average risk recommendations (above); may consider beginning screening before age 50 HIGH RISK Family history of FAP Early surveillance with endoscopy, counselling to consider genetic testing, and referral to a speciality center Puberty If genetic test is positive or polyposis is confirmed, consider colectomy; otherwise, endoscopy every year. Family history of HNPCC Colonoscopy and counselling to consider genetic testing Age 21 If genetic test is positive or patient has not had genetic testing, colonoscopy every 2 years until age 40, then every year. Inflammatory bowel disease Colonoscopies with biopsies for dysplasia. 8 years after the start of pancolitis; 12-15 years after the start of left-sided colitis. Every year.
*Approximately 70-80% of cases are from average-risk individuals, approximately 15-20% are from moderate-risk individuals, and 5-10% are from high-risk individuals.
** Digital rectal examination should be done at the time of each sigmoidoscopy, colonoscopy or DCBE.
$ Annual FOBT has been shown to reduce mortality from colorectal cancer, so it is preferable to no screening; however it is recommended that annual FOBT be accompanied by flexible sigmoidoscopy to further reduce the risk of colorectal cancer mortality.
$$ TCE includes either colonoscopy or DCBE. The choice of procedure should depend on the medical status of the patient and the relative quality of the medical examinations available in a specific community. Flexible sigmoidoscopy should be performed in those instances in which the rectosigmoid colon is not well visualised by DCBE. DCBE would be performed when the entire colon has not been adequately evaluated by colonoscopy.
# This assumes that a perioperative TCE was done.
DCBE = double-contrast barium enema; FOBT = fecal occult blood testing; TCE = total colon examination.
Size of adenoma Tubular Tubulovillous Villous adenoma 0.5-0.9 cms 0.3% 1.5% 2.5% 1.0-1.9 cms 3.6% 6.4% 5.7% 2.0-2.9 cms 6.5% 11.4% 17.0% 3.0 + 11.0% 15.0% 13.1% Total 2.8% 8.4% 9.5% Size of adenoma related to invasive carcinoma.