The definition of tumor deposits (TDs) in colonic adenocarcinoma has been modified in different editions of the AJCC/TNM staging system. Studies have shown that the presence of TD is associated with advanced tumor growth and poor prognosis. Most of these data were obtained in patients with simultaneous lymph node (LN) metastases. Reports focusing on the impact of TD in patients without LN metastasis are limited. We retrospectively restaged all right-sided colonic adenocarcinomas over a 10-year period using criteria from the fifth, sixth, and seventh AJCC edition. We compared the number of tumor nodule interpreted as LN and TD in each edition and evaluated the stage migration caused by TD definition change. We then assessed clinical significance of TD in the AJCC seventh edition by comparing 5-year overall survival of N1c patients versus other N category (N0, N1, N2) patients with similar T and M status. We showed that the average number of tumor nodules interpreted as LNs per case and the number of cases with positive LNs were significantly decreased with the seventh edition compared with fifth/sixth; however, numbers of cases with TDs and