COL6A3 and gastric cancer: The TCGA database was used to analyze the expression of 12 core genes, including COL1A1, COL1A2, COL3A1, COL5A1, BGN, COL6A3, FN1, COL11A1, COL6A2, COL4A2, GKN1, and VCAN in gastric cancer patients.