Risk stratification and detection of new colorectal neoplasms after colorectal cancer screening with faecal occult blood test: experiences from a Danish screening cohort.

Background: Limited data exist on adenoma surveillance as recommended in the European guidelines for quality assurance in colorectal cancer (CRC) screening and diagnosis after faecal occult blood test (FOBT) screening.

Objective: To assess the European guidelines for adenoma surveillance after CRC screening with FOBT.

Materials And Methods: This was a population-based cohort-study of 176 782 Danish individuals aged 50-74 years invited for CRC screening in 2005-2006. Adenoma patients were stratified into risk groups (low A, medium B, high C) in accordance with the European guidelines and followed up for recurrence of new neoplasms until the end of 2011. Risk ratios (RR) between the risk groups were calculated to assess differences in the recurrence rates of neoplasms.

Results: Among 84 803 screening participants, 2059 had positive FOBT, of whom 1861 underwent colonoscopy, and 709 patients had screen-detected adenomas. During a median follow-up period of 72.7 months, detection of new advanced adenomas (B+C) was significantly higher in risk group C than group A (RR 2.25, 95% confidence interval: 1.13-4.48). Nine patients were diagnosed with CRC: one in risk group A, two in B and six in C. The detection rate of CRC was higher in risk group C than A (RR 5.20, 95% confidence interval: 0.63-42.58), but not statistically significant. In risk group C, half of new advanced adenomas were detected within the first year and four of nine CRC were detected within 3 years.

Conclusion: Risk stratification of adenoma patients, as recommended by the European guidelines, is appropriate for postpolypectomy surveillance after FOBT screening.