The impact of tumor deposits on colonic adenocarcinoma AJCC TNM staging and outcome.

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 <12 LNs were significantly increased with the seventh edition compared with fifth/sixth. These changes, however, resulted in minimal effects on the final stage grouping. Our survival analysis showed that N1c patients had significantly worse survival compared with N0 patients. Although not statistically significant, the hazard ratios indicated that the N1c group might have worse survival than the N1 group and better survival than the N2 group. Therefore, we conclude that TDs predict patient outcome at least similarly to positive LNs.