L1CAM and gastric cancer: Recent evidence has demonstrated PSM analysis as a new statistical method for overcoming different patients’ characteristics and selection bias to increase the evidence level of a nonrandomised observational study.20 To validate the prognostic potential of L1CAM expression in GC patients, we conducted PSM analysis using FFPE cohort, and yielded 116 GC patients (58 patients in each group) for further analysis.