Endoscopic prediction of tumor invasion depth in early gastric signet ring cell carcinoma
Authors: H. Moon, S. Kang, J. Sung, H. Jeong
Journal: Annals of Oncology (2018)

Introduction: Endoscopic resection of early gastric cancer (EGC) is now widely accepted in many countries, especially in Korea and Japan. Endoscopic resection is often preferred over surgical resection due to better quality of life. signet ring cell carcinoma (SRC) is categorized as undifferentiated or a diffuse type, endoscopic treatment was originally not considered in early gastric SRC. However, recent studies have proven excellent prognosis of early gastric signet ring cell carcinoma with fewer lymph node (LN) metastasis. Thus, some now regard early gastric SRC as a condition for endoscopic treatment. However, many of them still do not accept endoscopic treatment of SRC due to several reasons. Depth prediction scoring systems have been developed based on the endoscopic features of all histologic types including differentiated and undifferentiated cancer. However, the same endoscopic criteria may not be applied to SRC due to different biological characteristics. We, therefore, evaluated the endoscopic features of M and SM cancers in early gastric SRCs. Methods: Medical records of early gastric SRC patients who underwent surgery or endoscopic resection, from January 2011 to December 2016 in 7 tertiary hospitals (Daejeon and Chungcheong province, South Korea), were reviewed to examine endoscopic findings and clinical data. Endoscopic features of the derivation group were analyzed, namely: tumor location, tumor size (mm), macroscopic morphology, fold convergence, and color change of lesions. From the results of the derivation group, we developed a depth prediction scoring system to distinguish M cancer from SM cancer. Statistical analysis was performed using the SPSS software (version 18.0, Chicago, IL, USA). A univariate analysis was performed using a chi square test, while the Fisher's exact test was used to evaluate the causal relationship between the risk of SM invasion and endoscopic features. A multivariate analysis was performed using a logistic regression analysis to calculate odds ratios (ORs) of SM invasion. To evaluate cut-off value for our depth prediction scoring system, ROC curve was used. The relative weightage of each factor in our depth prediction score system was based on their odds ratio. The accepted level of statistical significance was p < 0.05. Results: In total, 331 patients (129 patients, derivation group; 202 patients, validation group) were enrolled in this study. In the derivation group, the risk factors for SM invasion, namely fold convergence, nodular mucosal change, and deep depression were risk factors of SM invasion determined by logistic regression analysis (OR = 3.4, 5.9, 6.0, p < 0.05). A depth-prediction score was created by assigning 1 point for fold convergence and 2 points for other factors. When validation lesions of 0.5 points or more were diagnosed as SM invasion, the sensitivity and the specificity were 76.8%-78.6% and, 61.6%-74.7%, respectively. Conclusion: Fold convergence, nodular mucosal change, and deep depression are the risk factors for SM invasion cancer in early gastric SRCs. Our depth prediction scoring system may be useful for differentiating SM cancers.