Risk Factors of Positive Resection Margin in Laparoscopic and Open Liver Surgery for Colorectal Liver Metastases: A New Perspective in the Perioperative Assessment A European Multicenter Study

Objective: To assess the risk factors associated with R1 resection in patients undergoing OLS and LLS for CRLMs. Background: The clinical impact of R1 resection in liver surgery for CRLMs has been continuously appraised, but R1 risk factors have not been clearly defined yet. Methods: A cohort study of patients who underwent OLS and LLS for CRLMs in 9 European high-volume referral centers was performed. A multivariate analysis and the receiver operating characteristic curves were used to investigate the risk factors for R1 resection. A model predicting the likelihood of R1 resection was developed. Results: Overall, 3387 consecutive liver resections for CRLMs were included. OLS was performed in 1792 cases whereas LLS in 1595; the R1 resection rate was 14% and 14.2%, respectively. The risk factors for R1 resection were: The type of resection (nonanatomic and anatomic/nonanatomic), the number of nodules and the size of tumor. In the LLS group only, blood loss was a risk factor, whereas the Pringle maneuver had a protective effect. The predictive size of tumor for R1 resection was >45mm in OLS and >30mm in LLS, > 2 lesions was significative in both groups and blood loss >350 cc in LLS. The model was able to predict R1 resection in OLS (area under curve 0.712; 95% confidence interval 0.665-0.739) and in LLS (area under curve 0.724; 95% confidence interval 0.671-0.745). Conclusions: The study describes the risk factors for R1 resection after liver surgery for CRLMs, which may be used to plan better the perioperative strategies to reduce the incidence of R1 resection during OLS and LLS.