Oncological Outcomes of Varying Resection Margin Lengths in Colon Cancer Surgery: A Retrospective Analysis

In colon cancer surgery, the current Japanese guidelines recommend a resection margin of ≥10 cm to prevent local recurrence. However, achieving this length can be difficult in certain clinical scenarios. The optimal resection margin length and its impact on oncological outcomes remain controversial. This retrospective study analyzed 148 patients with stage II/III colon cancer who underwent curative laparoscopic resection between 2013 and 2019. Patients were grouped by the shortest resection margin as follows: Group 1 (<5.0 cm), Group 2 (5.0-9.9 cm), and Group 3 (≥10.0 cm). Disease-free survival (DFS) and overall survival (OS) were evaluated using Kaplan-Meier and Cox regression analyses. Propensity score matching (PSM) was applied to minimize selection bias between Groups 2 and 3. Group 1 had significantly poorer DFS and OS than Groups 2 and 3 (p=0.004 and p=0.0448, respectively). No significant differences in DFS or OS were found between Groups 2 and 3 before or after PSM. After 1:1 matching, DFS and OS remained comparable between the two groups (p=0.9339 and p=0.4857, respectively). A resection margin ≥5.0 cm was associated with oncological outcomes equivalent to those achieved with margins ≥10.0 cm. Margins of <5.0 cm were linked to poorer survival, suggesting a higher risk of recurrence. These findings support a revision of the rigid 10-cm margin guideline, and suggest that a ≥5.0-cm margin may be sufficient for favorable outcomes in laparoscopic colon cancer surgery.