Is the seventh edition of the UICC/AJCC TNM staging system reasonable for patients with tumor deposits in colorectal cancer?

Abstract

To assess the rationality of the seventh edition of TNM staging system on tumor deposits (TDs) and propose a novel subclassification. The TDs had been debated for many years. The seventh edition of TNM staging system proposed a "pN1c" concept. However, the value of the modification is still debated. A total of 1541 patients with colorectal cancer were reviewed. Overall survival rates were compared between patients without LNM but TD (+), and those who were TD (-). The TDs were stratified into the "any T + any N" category. Two-step multivariate analysis was performed to identify significant prognostic factors. Univariate analysis was used to determine whether a correlation existed between the number of TDs and prognosis. There was a significant prognostic difference between patients without LNM or TDs compared with those with positive TDs. Only in T3N2bM0 there was a significant prognostic difference between LNM (+), TD (+) patients and TD (-) patients. The seventh edition of TNM staging system was substituted by the novel TNM staging system in 2-step multivariate analysis. Only in T3N1cM0 there was a significant prognostic difference between patients with only 1 TD and those with more than 1 TD. The seventh edition of TNM staging system on TDs satisfactorily predicts patients' outcome for those without LNM. Patients who categorized as T3N2bM0TD (+) and T4N2bM0TD (-/+) should be reclassified as stage IV. Number of TDs was not an independent prognostic parameter in the TNM staging system.