Post-therapy pathologic tumor volume predicts survival in gastric cancer patients who underwent neoadjuvant chemotherapy and gastrectomy

Background To demonstrate that post-therapy pathological tumor volume (ypTV) should be considered as an independent prognostic factor in advanced gastric cancer (GC) patients who underwent neoadjuvant chemotherapy (NAC) and gastrectomy. Methods A total of 253 GC patients who received gastrectomy between January 2010 and December 2016 in our hospital were enrolled in this study. Clinicopathologic factors were evaluated using univariable and multivariable analysis. ypTV was calculated using pi* (tumor diameter/2)(2) *tumor invasion depth (cm(3)). Results Cut-point survival analysis demonstrated that the appropriate cut-offs for ypTV were 3, 6, 10, and 19 (cm(3)). Patients with tumor volumes of 0-3.0, 3.1-6.0, 6.1-10.0, 10.1-19.0, >= 19.1 cm(3) were defined as ypTV1, 2, 3, 4a and 4b. Using multivariable analysis, the tumor volume (ypTV stage, P < 0.05), ypN stage (P < 0.05), response to NAC (P < 0.05), vascular invasion (P < 0.05) and ypTvNM staging (P < 0.05) were independent prognostic factors. Kaplan-Meier analysis demonstrated that the 8th AJCC/UICC ypTNM staging was not a significant predictor for survival (P > 0.05); however, our newly defined ypTvNM staging was a significant predictor for survival (P < 0.05). Conclusions ypTV should be considered as an independent prognostic factor for GC patients after NAC. ypTvNM staging should be recommended to improve the accuracy of prognostic prediction for GC patients who received NAC plus gastrectomy.