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 (%ΔTIU(p) and %ΔTIU(d)) were significantly correlated with TRG (P < .001). The ypN stage, %ΔTIU(p), and %ΔTIU(d) were significant factors influencing progression-free survival (PFS) (P < .050). A value of %ΔTIU(d) ≤ 62.19% was associated with negative prognosis [relative risk (RR):2.103; P = 0.021], as was ypN stage (RR: 4.250; P = .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. %ΔTIU(d) represents a strong independent prognostic factor, increasing preoperative risk assessment performance.