[Accuracy comparision of abdominal enhanced CT and endoscopic ultrasound in the staging of gastric cancer after neoadjuvant chemotherapy: a post hoc analysis of a randomized clinical trial].

Objective: To compare the accuracy of abdominal enhanced CT and endoscopic ultrasound in the staging of gastric cancer after neoadjuvant chemotherapy (yc stage). Methods: Clinic data of 86 locally advanced gastric cancer patients admitted in Gastrointestinal Cancer Center, Peking University Cancer Hospital & Institute from April 2015 to November 2017 were analyzed retrospectively. Totally 86 patients completed both abdominal enhanced CT and endoscopic ultrasound after neoadjuvant chemotherapy. There were 60 males and 26 females, aged (57.8±9.7) years (range: 32 to 76 years). The diagnostic accuracy of abdominal enhanced CT and endoscopic ultrasound for yc stage were calculated by the area under the multiclass receiver operation characteristic curve (M-AUC), retrospectively. McNemar test was used to compared the diagnostic sensitivity. Results: The M-AUC of ycT stage evaluated by abdominal enhanced CT (CT-ycT stage) and by endoscopic ultrasound (EUS-ycT stage) was 0.614 and 0.704, respectively. For middle and lower gastric cancer, the M-AUC of CT-ycT stage was 0.599 and 0.613, respectively, while EUS-ycT stage was 0.558 and 0.709, respectively. For tumor in the lesser and non-lesser curvature, the M-AUC of CT-ycT stage was 0.630 and 0.607, respectively, while EUS-ycT stage was 0.616 and 0.749, respectively. For patients in CT-ycT1-CT-ycT4, there was no statistically significant difference in the sensitivity between CT-ycT stage and EUS-ycT stage (2/18, 2/15, 52.8%(19/36), 8/13 vs. 0, 4/15, 55.6%(20/36), 7/13; χ(2)=2.00, P=0.157; χ(2)=2.00, P=0.157; χ(2)=0.08, P=0.782; χ(2)=0.33, P=0.564). The M-AUC of ycN stage evaluated by abdominal enhanced CT (CT-ycN stage) was 0.654, while ycN stage evaluated by endoscopic ultrasound (EUS-ycN stage) was 0.533. For patients in CT-ycN0, there was statistically significant difference in the sensitivity between CT-ycN stage and EUS-ycN stage (12.7%(7/55) vs. 5.5%(3/55); χ(2)=4.00, P=0.046). For patients in CT-ycN1, N2, and N3, there was no statistically significant difference in the sensitivity between CT-ycN stage and EUS-ycN stage (2/19, 1/10, 0 vs. 1/19, 1/10, 0; χ(2)=1.00, P=0.317; the other P cannot be estimated). Conclusions: There was no significant difference between the diagnostic efficacy of abdominal enhanced CT and endoscopic ultrasound for yc stage of gastric cancer. Considering the invasiveness of ultrasound gastroscopy, it should not be recommend for patients after neoadjuvant chemotherapy routinely.