Risk of post colonoscopy colorectal cancer following screening colonoscopy with low-risk or no adenomas: A population-based study

Aim: In the Danish faecal occult blood test based bowel cancer screening programme, the first round was rolled out over 4 years. After roll-out, the planned faecal test recall procedure for individuals with either no or low risk adenomas at colonoscopy is 8 and 2 years, respectively. Here, we aimed to investigate the post colonoscopy colorectal cancer incidence in these two groups. Methods: All Danish screening individuals from 2014 to 2015 with a positive faecal test and either no or low risk adenomas at colonoscopy were included and followed for 3 years post screening for the event of colorectal cancer through national registries. Results: Out of 533,023 submitted faecal tests and 36,673 positive tests, 17,627 had no or low risk adenomas. We identified 60 (0.34%) individuals diagnosed with colorectal cancer within 3 years, 18 (0.29%) in the low risk adenoma group, and 42 (0.37%) in the no adenomas group (p = 0.44). Advancing age (HR = 1.079, p < 0.001) and higher faecal test value (HR = 1.001, p = 0.002) increased hazard of colorectal cancer occurrence, whereas male sex (HR = 1.3, p = 0.308) and having low risk adenomas (HR = 0.729, p = 0.264) did not. Conclusion: We found no difference in post colonoscopy colorectal cancer occurrence between individuals with either no or low risk adenomas. Instead, advancing age and increased faecal test value was associated with a higher risk of post colonoscopy colorectal cancer.