Introduction Analysis of interval bowel cancer rates within two years of a negative screening test kit result demonstrates rates twice as high following an equivocal FOB (Faecal Occult Blood test) with a negative FIT (Faecal Immunochemical Test), compared to a negative FOB. This analysis looks at the time to bowel cancer diagnosis following a negative FIT result to see whether participants may benefit from being recalled earlier for bowel screening than the current two year strategy.
Methods In Wales, the routine recall interval is two years. A cohort of participants with negative results validated between Oct 2008 and August 2010 were reviewed, with two years follow up data. These records were compared with all screen detected and symptomatic bowel cancers diagnosed in the two year follow up time period. The time interval from the negative screening result to their diagnosis of bowel cancer was recorded.
Results In the analysis time period, 9000 participants were issued with a negative FIT screening test result, 22 went on to develop bowel cancer within the next 2 years (0.24%). This compared to 0.14% of participants who had a negative FOB and were returned to routine recall (almost significantly different).
Of the 22 participants with cancer diagnosed following a negative FIT screening test result, the mean time to diagnosis was 366 days (median 316 days). However this varied depending on gender and five year age group.
29% women had a bowel cancer diagnosed within 3 months of their negative test result, compared to 7% men. At 6 months 20% men had been diagnosed with cancer. Similarly with the younger age group, 18% of participants aged 60–64 years had a bowel cancer diagnosed within 3 months, compared to 9% of those aged 65 years and older.
Analysing the potential costs of a tailored approach towards these equivocal test results, the cost to the bowel screening programme in Wales per year would be around 5,000 invitation letters with test kits to be posted out earlier (rather than at the two year routine recall interval). These potentially have the ability to diagnose the expected 10 cancers that would occur in the following twelve months.
Conclusion Women and the younger age group (60–64 years) may benefit from an early repeat test either at three months or immediately following their negative FIT test result. Men and the older age group (65 years and above) may benefit from an early repeat test at six months. It is unclear whether these are false negatives or true interval cancers but these preliminary results would suggest that if validated in a larger cohort, a tailored approach to equivocal FOB tests may optimise yield and potentially reduce the incidence of interval cancers.
Disclosure of Interest None Declared.
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