Hazard function analysis of metastatic recurrence after colorectal cancer surgery—A nationwide retrospective study

Abstract Background and Objectives An optimal postoperative surveillance protocol for colorectal cancer (CRC) is dependent on understanding the time line of recurrence. By hazard function analysis, this study aimed at evaluating the time of occurrence of metastasis. Methods A total of 21,671 Stage I–III colon cancer patients were retrospectively included from the Japanese study group for postoperative follow‐up of colorectal cancer database. Results The 5‐year incidence by metastasized organ was 6.3% for liver (right:left = 5.5%:7.0%, p = .0067), 6.0% for lung (right:left:rectum = 3.7%:4.4%:8.8%, p = 7.05E−45), and 2.0% for peritoneal (right:left:rectum = 3.1%:2.0%:1.2%, p = 1.29E−12). The peak of liver metastasis hazard rate (HR) (0.67 years) was earlier and higher than those of other metastases. The peak HR tended to be delayed in early stage CRCs (0.91, 0.76, and 0.52 years; for Stages I, II, and III, respectively). When analyzed as per the primary tumor location (right‐sided, left‐sided, and rectum), the peak HR for lung metastasis was twice as high for rectal cancer than for colon cancer, and peritoneal metastasis had a high HR in right‐sided colon cancers. Conclusion The time course for the risk of recurrence in various metastatic organs based on the primary tumor site was clearly visualized in this study. This will aid in individualizing postoperative surveillance schedules.