24. TRG better evaluate pathological response and predict prognosis of gastric cancer patients following neoadjuvant chemotherapy

Objective: As preoperative chemotherapy for gastric cancer was adopted widely, it is highly necessary to choose the criteria most suitable for response evaluation. In this study we mainly compare the efficacy of two response evaluation standards, so as to find out the more reliable and reproducible one.
Methods (Materials): Tumor regression grade (TRG) and grading based on percentage of residual tumor cells were evaluated separately and respectively by two pathologists in 180 gastric cancer patients. Distribution, correlation and prognosis value of two criteria was investigated.
Results: Patients with higher TRG grade also have more residual tumor cells, but one grade can’t be converted to the other. TRG had better Inter-observer agreement than the other (K=0.928 vs. K=0.838). Both of them correlate well with 5 years overall survival, but pTNM stage greatly affected prognosis value of the latter. Combination of TRG and pTNM stage could predict survival longer than 3 years with optimal sensitivity and specificity.
Conclusions: TRG and Residual tumor cell percentage grading system can’t be integrated together despite much accordance between them. TRG system should be preferred according to the result of our study. Combination of ypTNM stage and TRG could predict the prognosis of gastric cancer patients following induction chemotherapy more precisely.