Huntley and colleagues report higher colorectal cancer (CRC) incidence among mismatch repair (MMR) pathogenic variant carriers with a mean surveillance interval (MSVI) of ≤2 years and discuss overdiagnosis as one possible explanation.1 The cumulative-risk result, however, changes direction in the ≥1 year sensitivity cohort. In the primary analysis, cumulative CRC risk at age 74 was 63.4% (95% CI 53.3% to 73.5%) for MSVI ≤2 years and 37.4% (31.8% to 42.9%) for MSVI >2 years.1 After excluding 603 individuals with <1 year of follow-up (), reproduced from online supplemental table 20 of Huntley et al, it reports 32.4% (27.1% to 37.8%) and 51.4% (41.6% to 61.2%), respectively. The direction therefore reverses.

That reversal is difficult to reconcile with the other incidence summaries from the same ≥1 year cohort. CRC occurred in 108/1373 (7.9%) participants with MSVI ≤2 years and 146/2756 (5.3%) with MSVI >2 years; every reported 5-year age-band incidence-rate point…