Effects Of Low Skeletal Muscle Content Defined By L3 Plane Of CT Images On Clinical Status, Short-term Prognosis And Long-term Survival In Patients With Gastric Cancer

Background Clinical studies have shown that patients with gastric cancer combined with muscle decay generally have worse clinical outcomes.However,the diagnostic consensus given by AWGS-2 is complex and lacks the cut-off value of CT diagnosis recommended by EWGSOP-2 as the "gold standard".Objective The purpose of this study was to analyze the musculomic information extracted from the L3 plane of CT images in patients with gastric cancer,so as to explore the applicability of CT in the diagnosis of sarcopenia in patients with gastric cancer in the gastrointestinal surgery department and its ability to predict the long-term survival of patients with gastric cancer,and to provide a new research basis for the CT diagnosis of gastric cancer-related sarcopenia.Methods In this study,patients who underwent gastric resection and preoperative abdominal CT examination in the First Ward of Gastrointestinal Surgery Department of the First Affiliated Hospital of Anhui Medical University from 29 th,December,2016 to 29 th,August,2017 were continuously collected in a retrospective study.Firstly,clinical information of patients was collected.The results included clinicopathological features,systemic inflammatory response indicators,short-term prognosis,and 3-year survival(follow-up dates were from 29 th,December,2021 to 7th,January,2022).After inclusion and exclusion criteria,patients with complete abdominal CT images of5 mm were retained.Subsequently,DICOM files of patients’ preoperative computed tomography(CT)images were obtained.3D Slicer software was used to select the muscles and fat of the region of interest(ROI)in the third lumbar spine(L3)plane,and to extract radiomics features and body composition data.According to L3 skeletal muscle index(SMI),patients were divided into sarcopenia group and non-sarcopenia group.Baseline data were expressed as "mean±SD" or median.Kolmogorov-Smimov method was used to test the normality of variables,Mann-Whitney U test or Student-t test was used to compare continuous variables,and x2 test was used to compare categorical variables.Survival curves were calculated by Kaplan-Meier method,and differences between survival curves were tested by log-rank.Spearman’s rank test was used for correlation comparison of human body composition data,and the extracted image omics features were reduced and screened by LASSO-COX regression method,and the image omics score was constructed.Variables associated with long-term survival were screened by univariate and multivariate Cox regression tests for body composition data and clinicopathological features.ROC curve and calibration curve were used to verify the model construction.Results Among the 184 patients,148 were diagnosed as sarcopenia by "Criterion 1",with a prevalence rate of 79.35%.81 patients were diagnosed as sarcopenia by "Standard 2",with a prevalence of 44.02%.Forty patients were diagnosed with "Criteria3" sarcopenia,with a prevalence of 21.7%.Univariate COX regression model showed that body composition indicators SMI,PMA,PMG,BMI,age,degree of tumor invasion,TMN grade,and sarcopenia(criteria 2 and 3)may be prognostic factors for postoperative long-term survival of gastric cancer patients.Multivariate COX regression analysis showed that among muscle-related indicators,the criterion 3 diagnosis of sarcopenia was shown to be an independent risk factor for long-term survival of patients undergoing surgery for gastric cancer in most models(p < 0.05,HR=2.166,95%CI=1.0984-4.270).Only PMA was an independent factor for long-term survival of patients undergoing surgery for gastric cancer in all models(p < 0.05,HR=0.8444,95%CI=0.7335-0.9720).The sensitivity,specificity,truncation,and AUC of long term survival were 75.3%,60.2%,-1.258639,and 0.709(95%CI,0.627-0.790),respectively,based on the imaging scores of the radiomics features.The C index for predicting the survival of gastric cancer patients 1 year after surgery was 0.76561808,and the C index for predicting the survival of gastric cancer patients 3 years after surgery was 0.68618335.Conclusion PMA is significantly associated with long-term prognosis in patients with gastric cancer,and reduced PMA predicts worse clinical outcome in patients undergoing surgery for gastric cancer.Compared with PMA and SMI,the radiomics scores obtained from the computed tomography features of the psoas muscle have a better ability to predict the long-term survival status of patients undergoing surgery for gastric cancer,but they still cannot predict independently.The L3 SMI cutoff value obtained by Zhuang et al is still the priority in the diagnosis of muscle attenuation of patients with stomach cancer in our country.