Considering colorectal screening

In discussing my commentary about colorectal cancer screening,¹ Ted Mitchell is quite right to point out the importance of informed consent for cancer screening. The Cancer Care Ontario² and NCCCS³ reports both emphasize this point. However, it is inappropriate to suggest that these reports do not reflect a “thoughtful weighing of the risks.” Both groups included strong consumer representation and put much thought into the issue.

Mitchell is also concerned that colorectal screening will place a new burden on family doctors. However, this burden would be minimized if provincial governments introduced organized screening programs, with provisions for follow-up recall and timely colonoscopy assessment.

There are 3 problems with Bruce Brady's analysis. First, it should be remembered that an intervention with a modest clinical (i.e., individual) benefit can still have a significant population impact. The 20% reduction in mortality projected by the Cancer Care Ontario report² would result in about 1500 fewer deaths from colorectal cancer annually in Canada by 2015. Second, cost-effectiveness does not necessarily depend “strongly” on participation rate. In fact, a colorectal screening program would have relatively low fixed costs and high discretionary costs. Our own (unpublished) work at Cancer Care Ontario suggested that the cost- effectiveness curve is very flat above 20% participation, which is hardly a daunting target. Third, Brady refers to a national screening program as an “experiment,” but it would be more appropriate to view the randomized clinical trials as the experiments. An evidence-based program emulating these randomized clinical trials would be good health policy, not just an experiment.

Brady is properly concerned about the risks of colonoscopy assessment by inexperienced operators. This is a compelling reason for offering colorectal screening through an organized program rather than on an ad hoc basis (as would be the case with simply issuing clinical guidelines).

With regard to Gordon McLauchlan's letter, there is no need to choose between starting colorectal screening with FOB testing (because we are able to do so) and building our endoscopy capacity so that some day we can replace FOB testing with endoscopy.

Richard Schabas Chief of Staff York Central Hospital Richmond Hill, Ont.