Evaluating the prognostic significance of tumor deposits in gastric cancer and strategies for their integration into the TNM staging system: a single-center retrospective study.

Abstract

Purpose: To propose a new optimal strategy for incorporating tumor deposit (TD) into TNM staging.

Methods: Totally, 2730 consecutive gastric cancer (GC) patients were included according to the presence and count of TDs between January 2011 and December 2014. Overall survival (OS) was analyzed using Cox regression and propensity score matching (PSM). The relationship between the number of TDs and GC patients' prognosis was analyzed using restricted cubic spline curves and compared with the prognostic value of lymph node metastases (LNMs). Harrell's C-index (C-index) and the Akaike information criterion (AIC) were employed to assess the prognostic performance of different staging systems.

Results: The positive rate of TD was 9.67% (264/2730). The presence of TD was associated with poorer OS before PSM (hazard ratio (HR): 3.31; 95% confidence interval (CI): 2.84, 3.85) and after PSM (HR: 1.62; 95%CI: 1.31, 2.00). The modified TNM staging, equating one TD to four LNMs, achieved superior prognostic performance, surpassing the 8th edition AJCC TNM staging and other modified systems (C-index: 0.751, AIC: 15954.0). In this system, 12.04% (26/216) of TD-positive patients were upstaged from stage II to stage III. These upstaged patients had worse outcomes than the remaining stage II patients (HR: 10.97; 95% CI: 4.55-26.44), while outcomes were similar to those of original stage III patients (HR:1.08; 95%CI: 0.66, 1.78).

Conclusion: The presence and increased number of TDs were noted to be associated with GC patients' poor prognosis. Integrating TD count with LNMs could enhance the prognostic accuracy of the TNM staging system.