| Objective: The aims of this study were to evaluate the clinical application ofcontrast-enhanced MSCT with the receiver operating characteristic curve in the assessment ofearly response during chemotherapy in patients with advanced gastric cancer (AGC), and toclarify the differential diagnostic accuracy of the best parameter and the optimal cutoff value.Methods: A total of 36 patients with advanced gastric adenocarcinoma, received four cycleschemotherapy (FOLFOX 6 ) in tumor hospital of Shanxi Province from October 2010 to October2011 ,were prospectively enrolled in our study. 31 male and 5 female were included in this study,with the average age of 60.33 9.58 years. Contrast-enhanced MSCT was obtained within 1week before and after 2 cycles of chemotherapy. Pre- and post-chemotherapy tumor density wasmeasured by drawing a region of interest around the margin of the entire tumor at the biggestsection in the portal venous phase. The thickness and the length were measured in the samesection. These parameters were repeated the measurement three times and calculated the average.The percentage of density or thickness or length reduction rate was calculated. Contrast-enhanced MSCT was obtained to differentiate the responders from the non-responders by theResponse Evaluation Criteria in solid Tumors (RECIST) after 4 cycles chemotherapy andconfirmed the response 4 to 6 weeks latter. Values of CT parameters before and 2 cycles afterchemotherapy were compared using the paired t-test. The diagnostic accuracy of MSCT in theevaluation of response to chemotherapy calculated by changes in density and diameter andvolume was evaluated with receiver operating curve (ROC) analysis. We got the optimal cutoffvalue been defined as the point on the ROC curve closest to the top left corner. Statisticalanalyses were performed using SPSS version 17.0 software for Windows. A P-value less than0.05 was considered to indicate statistical significance.Results:1.There was no significant different in sex and age between the two groups(P＞0.05).2. In the early stage of chemotherapy ,the different in the density and thickness of primary gastriccancer before and after chemotherapy were statistically significant(P＜0.05).The different in thelength was not significant (P=0.104).3.The percentage reduction rates of the density and thickness and length between the respondergroup and the non-responder group were statistically significant (P＜0.05).4. The area under the ROC cure in the density reduction rate or in the thickness reduction rate orin the length reduction rate was 0.867, 0.749, 0.751. The area under the ROC cure in the densityreduction rate was the largest. The reduction rate of density is the best parameter of MSCT in the early evaluation of response to chemotherapy. When the optimal cutoff of the density reductionrate of AGC was set to be 11.65%, the sensitivity or the specificity or the false negative rate wasor the false positive rate or the Youden’s index or the positive likelihood rate or the negativelikelihood rate was 81%,86.7%,19%,13.3%,0.68,6.1,0.22.Conclusion:1. The density reduction rate or the thickness reduction rate or the length reduction rate had ahigh clinical value in differentiating responder from non-responder in the early evaluation ofchemotherapy effect of AGC.2. The density reduction rate was better than the thickness reduction rate and the length reductionrate in differentiating responder from non-responder in the early evaluation of chemotherapyeffect of AGC.3. When the optimal cutoff of the density reduction rate of AGC was set to be 11.65% at theearly stage of the chemotherapy, the sensitivity and the specificity were the highest. |
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