In reply: Macrae and Hebbard fail to grasp the concept that colorectal cancer is the only potentially preventable cancer in men and one of the two preventable cancers in women. In any discussion about screening options, this fact must be kept clearly in focus.

In terms of surveillance of first-degree relatives, we doubt the available evidence is of sufficient quality to be certain whether the absolute risk is 1.82 or 2.25. In either event, we would advocate colonoscopic surveillance. We would, however, agree with Macrae and Hebbard on the importance of safety issues. Elsewhere we have advocated confining the performance of colonoscopies to endoscopists with Conjoint Committee Accreditation, and ensuring that the procedures are undertaken in accredited, suitably equipped facilities.1

We find it difficult to understand why Macrae and Hebbard believe that "the main message of the US National Polyp Study2 was that follow-up . . . is not needed at 12 months". Showing a reduction in expected cancers of 90% seems to us a far more important finding. We would, however, point out that our editorial does not advocate routine colonoscopic follow-up at 12 months.

In relation to the pilot faecal occult blood testing (FOBT) studies, we believe that Macrae and Hebbard have missed the point. They advocate delaying colorectal cancer screening for a further five years to await the results of studies which, many believe, will be both outdated and probably inconclusive. Their continued inflexible stand is one that is being rejected by a rapidly increasing number of countries, including the United States, Germany, Italy and the recently formed Global Alliance for the Prevention of Digestive Cancer. Colorectal cancer is the commonest cause of mortality in both non-smoking men and women, with a death from this disease every two hours in Australia.

We suggest that introducing screening is far more urgent than Macrae and Hebbard advocate. We re-emphasise the point that individuals should, if they wish, be provided with the opportunity of selecting a screening program from a menu of options chosen after discussion with their primary medical carer.