A new TNM staging system inclusive of intraoperitoneal free cancer cells in gastric cancer patients

Abstract

Objective To evaluate a new TNM staging system inclusive of intraperitoneal free cancer cells in terms of postoperative survival of patients with gastric cancer. Methods Free cancer cells (FCC) in the peritoneal washes of gastric cancer patients were estimated by measuring CEA mRNA levels using real-time RT-PCR. After 5-year follow-up, we get the cut-off value of CEA mRNA level by using MedCalc software to analyze the ROC curve. When CEA levels are more than the cut-off value, it may considered as FCC(+), and then using FCC(+) as distant metastasis (MI) to make a new TNM staging and analyze patients life-span. Results (1) Under the ROC curve analysis, when the cut-off value of CEA mHNA level was at 31.21 copies/ml, the Youden's index is the highest. (2) When FCC (+) considered as M1 to make a new TNM staging, the 5-year survival rate showed as below: Ⅰ-Ⅱ, P=0. 134; stage Ⅱ-Ⅲ P=0.004 and Ⅲ-Ⅳ P=0.022,repecetively. Conclusion (1) The best cut-off value of CEA mRNA levels for FCC in peritoneal washes is 31.2 copies/ml. (2) Our study demonstrated that application of FCC(+) in the TNM staging may have a better estimation of prognosis of patients suffering from advanced gastric cancer. Key words: Stomach neoplasms; Neoplasm staging; Prognosis; Reverse transcriptase polymerase train reaction; Free cancer cells