Impact of tumor deposits on the prognosis and chemotherapy efficacy in stage III colorectal cancer patients with different lymph node status: A retrospective cohort study in China

Background: The goal was to determine whether tumor deposits (TDs) had effects on the overall survival (OS), cancer-specific survival (CSS), disease-free survival (DFS) and responses to chemotherapy in advanced colorectal cancer (CRC) patients with different lymph node (N) stages. Materials and methods: The retrospective cohort study recruited 1455 stage III CRC patients diagnosed at a single institution between January 2010 and July 2016. Patients were divided into TDs negative and positive groups. Based on whether they accepted chemotherapy, patients were further divided into chemotherapy and non-chemotherapy groups. Kaplan-Meier methods, univariate and multivariate analyses, and subset analyses based on the N stage were performed to compare the OS, CSS and DFS between different groups. Results: Multivariate Cox analyses showed that TDs were independent prognostic markers for the OS (adjusted HR = 1.929, 95% CI: 1.339-2.777), CSS (adjusted HR = 1.789, 95% CI: 1.165-2.748) and DFS (adjusted HR = 2.179, 95% CI: 1.612-2.944) in all N stages combined. In addition, subset analyses based on the N stage further demonstrated that TDs were independent risk factors for the OS (P = 0.012), CSS (P = 0.010) and DFS (P < 0.001) in patients with the N1a, 1 b stages, and for the OS (P = 0.023) and DFS (P < 0.001) in patients with the N2a, 2 b stages. Furthermore, the OS, CSS and DFS in the TDs negative group could be extended significantly after the administration of chemotherapy, whereas patients with positive TDs lost the DFS benefit from chemotherapy. Conclusions: Stage III CRC patients with positive TDs had a poor prognosis, and they did not display a DFS benefit from chemotherapy. TDs had adverse effects on the OS and DFS in patients with the N1a, 1 b and N2a, 2 b stages, providing evidence for the feasibility of the new TNM category method.