Improved oncologic outcomes with increase of laparoscopic surgery in modified complete mesocolic excision with D3 lymph node dissection for T3/4a colon cancer: results of 1191 consecutive patients during a 10-year period: a retrospective cohort study.

BACKGROUND Laparoscopic modified complete mesocolic excision (mCME) with D3 lymph node dissection has been performed with increasing frequency, but the oncological safety remains unclear. This study investigated the oncological safety of laparoscopic modified CME with D3 dissection for pT3/4a M0 colon cancer. PATIENTS Consecutive patients with pT3/4a M0 colon cancer undergoing curative colectomy at a comprehensive cancer center between 2004 and 2013 were included. Outcomes were compared between early (2004-2008, n = 450) and late (2009-2014, n = 741) periods. Prognostic factors were investigated by multivariate analysis. RESULTS A total of 1191 patients were eligible. Median follow-up was 57 months. Laparoscopic surgeries were more common in the late period (early vs late: 53.6% vs. 91.8%, p < 0.01). Patients in the late period showed lower blood loss (20 mL vs. 10 mL, p < 0.01), higher number of harvested lymph nodes (18.1 vs. 21.6, p < 0.01) and fewer patients with < 12 harvested nodes (13.6% vs. 5.8%, p < 0.01). Postoperative complication rates were similar between periods (2.7% vs. 2.7%, p = 0.97). Five-year relapse-free survival rate (RFS) (75.3% vs. 82.7%, p < 0.01) and overall survival rate (OS) (86.9% vs. 91.7%, p = 0.01) were higher in the late period. Multivariate analysis revealed laparoscopic surgery as an independent favorable prognostic factor for both RFS (hazard ratio (HR) = 0.73, 95% confidence interval (CI) 0.54-0.99, p = 0.03) and OS (HR = 0.56, 95% CI 0.37-0.83, p < 0.01). CONCLUSION Improved oncologic outcomes and more frequent laparoscopic surgery during the 10-year period of the study were demonstrated for modified CME with D3 dissection, suggesting the safety of this procedure performed by experienced surgeons for pT3/4a M0 colon cancer.