Current Guidelines for Screening Colonoscopy
Guidelines have been developed as a way to make recommendations for screening colonoscopy based on known risk factors for colorectal cancer. The risk factors used for this “risk stratification” are age, family history of colorectal cancer and past history of colorectal adenoma or cancer. Risk stratification is not an exact science, but the guidelines are based on the known characteristics of colorectal cancer and the opinions of knowledgeable experts.
Average risk individuals:
A patient is considered average risk if he or she (1) has no family history of colorectal cancer or colorectal adenomas, (2) has no personal past history of colorectal cancer or colorectal adenomas, (3) has no complaints about his/her bowels (passing blood with a bowel movement, recent change in bowel habit, unexplained weight loss or abdominal discomfort), (4) has no findings on physical examination suspicious for an abnormal growth in the rectum or mass in the abdomen, and (5) has no unexplained iron deficiency anemia. Under current guidelines it is recommended that average risk individuals begin screening for colorectal adenomas at 50 years of age. If colonoscopic examination of the rectum, colon and cecum is satisfactory and no adenoma is found, the next examination for screening is done in 10 years. If polyps are found, follow up will be dictated by the number and type. Your provider will let you know what follow up is needed after the pathology is completed.
Family history of colorectal cancer:
There are several known genetic traits that may be inherited which increase the risk for development of colorectal cancer. Individuals who have a family history colorectal cancer or adenoma are at higher than average risk for colorectal cancer. It is important that you talk to your primary care provider if you have a family history of colorectal cancer or adenomatous polyps to see when you should have your colonoscopy scheduled.
In some families there are genetic traits that greatly increase the risk for developing colorectal cancer. The Hereditary Non-Polyposis Colorectal Cancer (HNPCC) Syndrome is of particular concern, because it accounts for 6 to 8 percent of colorectal cancer deaths in the United States. HNPCC may be suspected if the family history includes three or more relatives in two or more generations (at least one a first degree relative), one of whom developed colorectal cancer before the age of 50. There are additional factors that can be taken into account, including a family history of endometrial cancer, small intestine cancer, and cancer of the ureter or renal pelvis. Under current guidelines it is recommended that individuals at risk for HNPCC should undergo colonoscopy every 1-2 years starting at age 20-25 or 10 years younger than the age of the earliest diagnosis of cancer in the family, whichever is earlier. Those individuals who inherit a gene for HNPCC are at high risk (85% or more) of developing colorectal cancer, and cancers develop more rapidly than is typical for most colorectal tumors.
Familial polyposis coli:
A less common genetic trait is characterized by the development of colorectal adenomas early in life and the development of hundred or even thousands of adenomatous polyps that carry a high risk for colorectal cancer at a young age. Under current guidelines it is recommended that individuals at risk for familial polyposis coli begin screening with flexible sigmoidoscopy at age 10-12.