Colorectal cancer (CRC) is the
number two cancer killer in North America and, as the
population ages, is likely to increase in frequency.
So what can be done to reduce CRC deaths?
The first thing we need to do is
reduce risk factors in the general population. CRC is
increased in smokers, type II diabetics, obese patients,
heavy consumers of red meat and those who don't eat
enough fish, fruits, calcium and vegetables. In such
patients, counselling may be more beneficial in the
long run than screening.
Second, we need to identify and
aggressively screen high-risk populations. CRC is more
frequent in people with pelvic cancers treated with
radiotherapy, inflammatory bowel disease, a history
of adenomatous polyps or previous CRC and those with
family histories of colon cancer.
The third approach is to establish
screening programs for people without an increased risk
of developing colon cancer, as discussed in "GI
dearth stalls CRC screening" on page 7. Fecal occult
blood tests, even when combined with sigmoidoscopy,
that miss 25% of advanced neoplastic lesions are not
the answer. Air contrast barium enemas also frequently
miss advanced lesions and CT colonography was recently
rejected as a primary means of CRC screening in a study
in the October 11, 2005 issue of the CMAJ.
Thus, colonoscopy remains the best
screening method for CRC. It is, however, not the perfect
tool given the expense, risks of complications and inadequate
number of skilled clinicians in Canada. One proposed
solution has been the creation of freestanding endoscopy
clinics. However, recognizing that there are no standards
governing quality of care in these clinics, I cannot
support this solution. Similarly, to license nurse practitioners
to carry out endoscopy may not be a solution either.
Endoscopy is not a "see one, do one, teach one" endeavour
and advanced clinical judgement is required before subjecting
anyone to a potentially life-threatening procedure.
A colonic perforation is not a pretty thing!
We must stratify CRC risk in patients
and tailor the screening procedure to the risk. Patients
should be aware of the complications, costs, sensitivities
and specificities of the different screening tests and
become proactive in the decision process. In the future,
CT colonography may emerge as a viable screening tool,
as may fecal DNA testing. However, at present, the gold
standard remains colonoscopy carried out by qualified
practitioners in a hospital-based endoscopy suite.
— Robert J Fingerote MD,
FRCPC, Gastroenterologist, York Central Hospital, Richmond
Hill, Ontario
|
