Originally published in The Ottawa Citizen November 6, 2001
Original Title: Colonoscopy: A Means to an End?
Cancer of the colon and rectum, a leading cause of death in western society, is not as freely discussed as other more visible cancers. It usually spreads to the lung and liver, causing tremendous suffering and pain.
In August the Journal of Medical Screening reported the lifetime risk of colorectal cancer was one in 23 for men and one in 40 for women.
Among men, one in 200 in the 55 to 59 year age group will develop colorectal cancer. This risk rises to one in 23 by the time they reach 70 years of age. Among women, one in 400 will develop colorectal cancer between 55 and 59 and one in 40 among those aged 70-74.
This data was based upon a study population of 507,000 people in the French Côté d’Or region. By age 74 the risk of cancer is one in 13 for men and one in 23 for women if one first-degree family member (parent or sibling) had colorectal cancer. This jumps to one in four and one in seven for men and women respectively if two first-degree family members are affected.
Although family history is important, 75 per cent of those who develop colorectal cancer have no identifiable risk factors and are considered to be an average risk population. A family history is defined as two first-degree relatives (parents or siblings) with colon cancer or one first-degree relative who developed colon cancer prior to age 45.
It is a silent disease in its early stages. Mr. L., 53, had a family history of colon cancer. His mother was 74 when diagnosed. Mr. J., 51, reported that his father was discovered to have polyps in his colon in his mid-60s. Both men felt well. Both men saw Dr. Ken Chew, an Ottawa gastroenterologist, for colonoscopy.
A two-centimetre polyp was found in Mr. L.’s colon. The biopsy result was adenocarcinoma, an aggressive cancer. However, limited to the polyp itself, it along with 15 centimetres of his large intestine was removed. He is now free of his cancer and does not require chemotherapy.
Mr. J.’s colonoscopy revealed a five-centimetre cancerous polyp in the large intestine. It was more advanced, encroaching into the intestinal wall. He underwent surgery followed by chemotherapy. His chances for survival are excellent.
Colorectal cancer can be successfully treated and eradicated if caught in its early stages. The problem has been finding the right diagnostic tools to accurately detect early tumours or suspicious polyps.
Even with the right tools, at what age do we provide screening tests? In medicine, there are no absolutes. Guidelines for treatment and screening are consistently re-evaluated based on new research and evidence. A published study looking at the combination of testing stool for blood and sigmoidoscopy demonstrated that 24 per cent of cancers were missed using this technique. Those missed cancers were found using colonoscopy.
Sigmoidoscopy goes partially up into the intestine whereas colonoscopy tracks through the entire large intestine. About 18 to 24 hours prior to this procedure, a strong laxative is used to empty the bowel. Clear liquids like apple, cranberry and grape juice, bouillon Jell-o, black coffee or tea (no milk or sugar) can be taken for breakfast, lunch and dinner.
Some people prefer to be sedated for the procedure. It takes about 15 to 20 minutes. It can be uncomfortable.: There are small risks to colonoscopy. Small nicks in the bowel wall, bleeding or perforation occur in 0.1 per cent of people tested.
A new procedure is on the horizon; virtual colonoscopy. This technique uses MRI technology to create a 3-D image of the colon. Studies continue to evaluate its accuracy.
Colonoscopy is recommended for people of average risk after the age of 50. It is considered the standard for colorectal cancer screening because it can be threaded throughout the colon. This OHIP-covered procedure costs about $180. Those with a family history of colon cancer should have it done at age 40.
One school of thought suggests that, screening colonoscopies be performed beginning at 50 years of age and repeated every 10 years if no cancers are found. Yearly followups are recommended once colon cancer is detected and treated. This can change depending upon each individual’s condition.
Two hereditary genetic conditions, Hereditary Nonpolyposis colorectal cancer (three to eight per cent of colon cancers) and Familial Adenomatous Polyposis (one per cent of colon cancers), require earlier more frequent screening colonoscopies. If you have a family member who has this condition, it is imperative that your family be screened.
Mr. L. and Mr. J. can expect to live long and healthy lives. Let’s make sure everyone else has the same opportunity as well.
© Dr. Barry Dworkin 2001