A validated algorithm to ascertain colorectal cancer recurrence using registry resources in Denmark

Colorectal cancer recurrences are difficult to ascertain accurately and efficiently. We developed and validated an algorithm to identify recurrences that uses Danish medical registries. The algorithm uses metastasis and chemotherapy codes in the Danish National Patient Registry and codes indicating cancer recurrence in the Danish Pathology Registry. We applied the algorithm to a cohort (n = 21,246) of colorectal cancer patients diagnosed...