New CT Evaluation Methods Of Neoadjuvant Chemotherapy For Advanced Gastric Cancer

ObjectiveTo prospectively evaluate one-dimensional measurement, volumetric measurements and density measurement with computed tomography (CT) images in the assessment of response after neoadjuvant chemotherapy for advanced gastric cancer (AGC).MethodsAll patients with biopsy-proved AGC who received neoadjuvant chemotherapy at the first affiliated hospital of Zhejiang university between January2004and May2011and who met the inclusion and exclusion criteria listed below were included in this study. The primary tumor lesion and pathological nodes were identified as target lesions and measured with one-dimensional measurement,volumetric measurement and density measurement. Results before and after neochemotherapy were performed with a paired t-test. The optimal cutoff value for differentiating responders from non- responders was defined according to classification and regression tree analysis (CART). Overall Survival (OS) was estimated in all patients according to the Kaplan-Meier method. Statistical comparisons between different groups of patients were performed with the log-rank test.ResultsThe differences before and after neochemotherapy in one-dimensional measurement, volumetric measurement and density measurement were statistically significant. According to the CART analysis, the decrease of27%(sensitivity57.2%, specificity70.9%) in one-dimensional measurement and32%(sensitivity71.9%, specificity80.7%) in volumetric measurements were both their own optimal cutoff value for differentiating responders from non-responders, and the OS in responders was significantly longer (one-dimensional measurement, P=0.003; volume measurement, P<0.00001). The optimal cutoff of density measurement is non-existent. Of the42responders evaluated with one-dimensional measurement,31were volumetric responders and11, volumetric nonresponders, OS was significantly longer in the former than in the latter group (P<0.0001); Of the72responders evaluated with one-dimensional measurement,24were volumetric responders and48, volumetric nonresponders; OS was significantly longer in the former than in the latter group (P=0.005). ConclusionsBoth one-dimensional and volumetric measurements can be used in the evaluation of neoadjuvant chemotherapy for AGC, the decrease of32%in tumor volume as the distinction between responders and non-responders group has great sensitivity and specificity. However, density measurement seems cannot be used to evaluate the neoadjuvant chemotherapy for gastric cancer.