APOE and gastric adenocarcinoma: In the TCGA database, the APOE expression was statistically significantly higher in some tumor tissues compared to the matched control tissues, which include BRCA, HNSC, Liver hepatocellular carcinoma (LIHC), esophageal carcinoma (ESCA), prostate adenocarcinoma (PRAD), stomach adenocarcinoma (STAD), and thyroid carcinoma (THCA) (Fig. 1A, p-value less than 0.001).