Importance of the ratio of surgical margin to nodule size in pulmonary metastasectomy for colorectal carcinoma.

[OBJECTIVES] Pulmonary metastasectomy (PM) is a survival-enhancing treatment in the multimodal management of metastatic colorectal cancer (CRC). Given the high recurrence rates, we hypothesized that the adequacy of the surgical margin relative to nodule size might have prognostic value. This study aimed to analyze clinical characteristics and identify prognostic factors for disease-free survival (DFS) and overall survival (OS) in patients who underwent PM for CRC.

[METHODS] We retrospectively reviewed 105 patients who underwent PM for CRC metastases between January 2010 and December 2023. Survival outcomes were analyzed using Kaplan-Meier and Cox regression models. ROC analysis was used to determine the optimal cut-off value for the ratio of surgical margin (SM) to nodule size (NS).

[RESULTS] The optimal cut-off value for SM/NS was 0.61 for DFS (sensitivity: 80.5%, specificity: 57%, (95% CI 0.67-0.86; p < 0.001) and 0.59 (95% CI 0.61-0.82; p < 0.001) with a sensitivity of 83.7% and specificity of 57.1% for OS. Univariate analysis showed that CEA level, disease-free interval (DFI), and NS were significantly associated with both DFS and OS. SM/NS was also significant for both outcomes (p < 0.001 and p = 0.001). Multivariate analysis confirmed that CEA, DFI, NS, and SM/NS were independent prognostic factors for DFS and OS (all p < 0.05).

[CONCLUSIONS] SM/NS ratio may be a reliable prognostic factor in PM for CRC. A ratio of ≤ 0.6 was associated with poorer survival outcomes and could be a more consistent indicator than nodule size or margin width alone.