CT volumetry can potentially predict the local stage for gastric cancer after chemotherapy.

<bold>Purpose: </bold>We aimed to evaluate the value of CT tumor volumetry for predicting T and N stages of gastric cancer after chemotherapy, with pathologic results as the reference standard.<bold>Methods: </bold>This study retrospectively evaluated 42 patients diagnosed with gastric cancer, who underwent chemotherapy followed by surgery. Pre- and post-treatment CT tumor volumes (VT) were measured in portal venous phase and volume reduction ratios were calculated. Correlations between pre- and post-treatment VT, reduction ratio, and pathologic stages were analyzed. Receiver operator characteristic (ROC) analyses were also performed to assess diagnostic performance for prediction of downstaging to T0-2 stage and N0 stage.<bold>Results: </bold>Pretreatment VT, post-treatment VT, and VT reduction ratio were significantly correlated with T stage (rs=0.329, rs=0.546, rs= -0.422, respectively). Post-treatment VT and VT reduction ratio were significantly correlated with N stage (rs=0.442 and rs= -0.376, respectively). Pretreatment VT, post-treatment VT, and VT reduction ratio were significantly different between T0-2 and T3,4 stage tumors (P = 0.05, P < 0.001, and P = 0.002, respectively). The differences between N0 and ≥N1 groups were also statistically significant (P = 0.005 for post-treatment VT, P = 0.016 for VT reduction ratio, respectively). The area under the ROC curve (AUC) for identification of T0-2 groups was 0.70 for pretreatment VT, 0.88 for post-treatment VT, and 0.82 for VT reduction ratio, respectively. AUC was 0.78 for post-treatment VT and 0.74 for VT reduction ratio for identification of N0 groups.<bold>Conclusion: </bold>CT tumor volumetry, particularly post-treatment measurement of VT, is potentially valuable for predicting histopathologic T and N stages after chemotherapy in patients with gastric cancer. [ABSTRACT FROM AUTHOR]