BackgroundLymphadenectomy during right hemicolectomy for colon cancer varies between the U.S. and Japan. MethodsPatients undergoing right hemicolectomy for non-metastatic right-sided colon cancer between 2010 and 2019 at U.S. and Japanese institutions were compared. Outcomes included survival, pathologic findings, and postoperative complications. Results319 American patients (57 % female, mean age 70 years) underwent conventional resection and 308 Japanese patients (52 % female, mean age 70 years) underwent extended dissection. The conventional group underwent more laparotomies (26.6 % vs. 8.4 %, p < 0.001), had more poorly differentiated histology (31.7 % vs. 11.0 %, p < 0.01), lower lymph node yield (M = 27 ± 11 vs. M = 32 ± 14, p < 0.001), and more 30-day readmissions (31 vs. 5, p < 0.001). Adjusting for demographics, pathology, perioperative outcomes, and adjuvant chemotherapy, extended lymphadenectomy improved disease-free survival (HR 0.50; 95 % CI, 0.31–0.80; p = 0.004), but not overall survival (HR 0.98; 95 % CI, 0.95–1.02; p = 0.14). ConclusionsExtended lymphadenectomy for right sided-colon cancer improves disease-free, but not overall, survival among Japanese patients.