AbstractObjectiveWe investigated how Japanese D3 dissection with left colic artery (LCA) preservation affects anastomotic leakage after anterior resection with anastomosis for rectal cancer, based on the leak rate. The correlation between LCA preservation, survival, and cancer recurrence after resection was also analyzed.Summary and Background DataIt remains unclear how LCA preservation affects the anastomotic leak rate and oncological outcomes after resection remains unclear. Some reports suggested that anastomotic leakage increases local recurrence and decreases cancer‐specific survival.MethodsIn this study, we enrolled and analyzed 457 patients who underwent radical resection of rectal cancer in the period October 2011 through December 2016. The attending surgeon decided preoperatively and registered whether to preserve the LCA. This trial was registered under the UMIN‐CTR Identifier UMIN000006160.ResultsD3 with LCA preservation was successfully completed in 218 (89.3%) of the 244 patients registered in this group, whereas D3 without LCA preservation was successfully completed in all 213 patients registered in this group. After propensity score matching, the anastomotic leakage rate was 7.86% (11/140) after D3 with LCA preservation and 7.14% (10/140) after D3 without LCA preservation. The overall survival rates were 90.1% and 89.3%, and the recurrence‐free survival rates were 77.6% and 77.3%, respectively.ConclusionsOur findings suggest that LCA preservation has no effect on the incidence of anastomotic leakage after rectal resection with anastomosis using DST and that oncological outcomes may not be affected.