UICC World Cancer Congress 2006

Methods:As part of a UK demonstration pilot, two rounds of biennial FOBt screening has been offered to all individuals aged between 50 and 69 living in North-East Scotland (total population 1.5 million). A guaiac-based test was used, but in the second round, a sensitive immunological test was employed in a reflex "two tier" approach in an attempt to reduce the false positive rate.

Results: In the first (prevalence) round, the uptake was 55%, the positivity rate was 2.7% and the cancer detection rate was 2.1/1000 screened. In the second (incidence) round these figures were 53%, 1.9% and 1.2/1000 respectively. In the first round the positive predictive value of a positive test was 12% for cancer and 36.5% for adenoma; these fell to 6.8% and 29.5% in the second round. The percentage of screen-detected cancers diagnosed at stage A (early) was 49.2% in the first round and 38.4% in the second round, compared with 8% of symptomatic cancers diagnosed in the same time period. The use of the immunological test in the second round facilitated clinical risk stratification; of those with a negative immunological test following a positive guaiac test (38%), the risk of cancer was no greater than the general population risk. Based on the results of previous randomised trials, this study has confirmed that FOBt screening in Scotland should reduce colorectal cancer mortality by around 20%, and a comprehensive national programme is currently being rolled out.