Completeness and accuracy of the registration of recurrences in the Swedish Colorectal Cancer Registry (SCRCR) and an update of recurrence risk in colon cancer.

The registration of recurrences in the registry after 5 years is accurate to between 1 and 2% but less accurate earlier. A small number of unreported recurrences and falsely reported recurrences were discovered in the chart review. The recurrence risk in this validated and updated patient series matches what has been recently reported, except for the risk of recurrence in stage II low risk colon cancers which seem to be even a few percentage points lower (6 vs. 9%).