A long-term conditional survival analysis for gastric cancer based on 7th and 8th TNM classification in Eastern and...

To compare the power to predict the 5-year conditional disease-specific survival (CS5) between the 7th and 8th editions of the TNM for gastric cancer (GC) patients.

This retrospective study recruited 20,548 patients who underwent GC surgery from the databases of the Surveillance, Epidemiology, End Results and a center in Asia. The CS5 was evaluated with the 7th and 8th TNM classification.

A two-step model showed that at the 3-5th postoperative years, the 8th staging remained an independent risk factor, whereas there was no significant difference for 7th -edition staging. Further analysis of the ability to predict CS5 indicated that there were significant differences in the CS5 of 7th -edition stages IIb and IIIa at baseline and at the postoperative 1-4th years (all p < 0.05, Cohen's d > 0.5). However, the CS5 of the fifth year was similar between them (p = 0.307, Cohen's d = 0.35). Meanwhile, the results indicated that the 8th -edition staging could effectively determine the CS5 among stages Ⅰa, Ⅰb, Ⅱa, Ⅱb, Ⅲa, and Ⅲb at baseline and at the postoperative 1-5th years (all p < 0.05). However, neither the 7th - nor the 8th -edition staging could predict the CS5 for stages Ⅲb and Ⅲc from the postoperative third to fifth years (all p > 0.05).

For patients with stages IIB and IIIA GC, the 8th TNM has a higher discriminatory value than the 7th edition for CS5 after the postoperative fourth year. However, a more detailed classification system is still needed to predict conditional survival for GC.