Prognostic value of tumor deposits and positive lymph nodes in colorectal cancer surgery: improved staging for long-term prognosis.

Background: To evaluate the prognostic value of the presence and number of tumor deposits (TDs) and the combination of TDs and number of positive lymph nodes (PLNs) in patients undergoing colorectal cancer (CRC) surgery, and to modify N staging.

Method: The clinical data of 1470 patients with stage I-IV CRC who underwent surgery in Wuhan Union Hospital from February 2014 to May 2018 were collected. The optimal cutoff value for TD + PLNs was obtained using X-tile software, and patients were regrouped accordingly. Cox univariate and multivariate analysis were used to screen the factors affecting the prognosis of patients. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) were used to evaluate the predictive ability of independent prognostic factors for overall survival (OS) and disease-free survival (DFS) of patients.

Result: The presence of TD was associated with poor OS (HR = 2.478, 95%CI: 1.794-3.422, P<0.001) and DFS (HR = 2.516, 95%Cl: 1.874-3.377, P<0.001). Combined with TD and PLNs, a total of 128 of 395 N1 patients were reclassified re-staged as N2(TD + PLNs ≥ 3), which had a worse prognosis than those diagnosed with N1. Compared with Tumor Node Metastasis stage and TD number, the multivariate model constructed using independent prognostic factors showed better predictive power for OS (AUC:0.769 vs. 0.681 vs. 0.650) and DFS (AUC:0.757 vs. 0.702 vs. 0.650).

Conclusion: TD significantly affects the long-term prognosis of CRC patients. Combining TD and PLNs to redefine the tumor staging of CRC patients can improve the accuracy of long-term prognosis of surgical patients.