Prognostic role of iodine values for gastric cancer after neoadjuvant chemotherapy: a strong independent prognostic factor.

PURPOSE We aimed to systematically explore the value of iodine values calculated from dual-energy computed tomography (DECT) as potential prognostic factors for locally advanced gastric cancer (LAGC) patients undergoing neoadjuvant chemotherapy (NAC). METHODS Eighty-five LAGC patients were examined using DECT before and after NAC and were divided into responders and non-responders based on the tumor regression grade (TRG). The iodine values, including portal- and delayed-phase iodine uptake (IU-p and IU-d, mg/ml) and total iodine uptake (TIU-p and TIU-d, mg) were acquired. Correlations between the reduction ratios of iodine values and TRG were analyzed. The diagnostic performance of parameters for differentiating responders from non-responders was calculated. Kaplan-Meier method was used for survival analysis. RESULTS The reduction ratios of total iodine uptake (%△TIU-p and %△TIU-d) were significantly correlated with TRG (p < 0.001). The ypN stage, %△TIU-p and %△TIU-d were significant factors influencing PFS (p < 0.050). A value of %△TIU-d≤62.19% was associated with negative prognosis [relative risk (RR):2.103; P = 0.021], as was ypN stage (RR:4.250; p = 0.003). CONCLUSION Iodine values (especially the TIU) are noninvasive quantitative parameters that are potentially helpful for evaluating the treatment response and survival prognosis of LAGC after NAC. %△TIU-d represents a strong independent prognostic factor, increasing preoperative risk assessment performance.