COL18A1 and gastric cancer: From the 12 included studies, 10 studies [10, 22, 23, 32–38] containing 922 subjects (sample size range, 30–130) measured the serum endostatin levels in GC patients and the controls, as well as in different clinicopathological stages, such as TNM stage, histologic grade, invasive grade, and LN metastasis.