Proposal of a Stage-specific Surveillance Strategy for Colorectal Cancer Patients: A Retrospective Analysis of Japanese Large Cohort

Background: Frequency and duration of postoperative surveillance for colorectal cancer patients remain debatable, and follow-up data regarding stage I or resected stage IV patients are limited.

Method: Cohort data from 22 institutions were retrospectively analyzed; 18,841 patients who underwent curative surgery for stage I to IV cancer were included. The cumulative incidence of recurrence, recurrence rate over surveillance period, and risk of recurrence each year after surgery were assessed.

Results: Recurrence rates in stages I, II, III, and IV were 4.2%, 14%, 32%, and 75%, respectively. Over 80% of recurrences occurred within the first 2 years in stage IV, and 3 years in stages II and III, whereas 86.8% of recurrences occurred in 5 years in stage I. Among patients with 5-year recurrence-free survival, 2.2% in stage III and 7.0% in stage IV still experienced recurrence after the 5-year postoperative period. When the duration is extended to 6 years in stage III and 8 years in stage IV, approximately 1% over the surveillance period would be achieved. In stage I, the risk of recurrence each year after surgery was consistently low, whereas the risks in stages II, III, and IV were high in the early postoperative phase. The risk of recurrence each year in stages III and IV patients were over 2-fold and 6-fold higher than that in stage II, respectively.

Conclusions: Recurrence patterns were markedly different according to cancer stages. These results suggest that a stage-specific approach to postoperative surveillance may improve the efficiency of detecting recurrences.