COL1A1 and gastric cancer: Collagen I is composed of collagen type I alpha 1 (COL1A1) and COL1A2. COL1A1 and COL1A2 mRNA expression in GC tissues is significantly higher than that in normal gastric mucosa tissues, and higher COL1A1 and COL1A2 expression levels were associated with lower overall survival rates [36]. COL1A1 may be a potential monitoring factor for screening early GC, and COL1A1 and COL1A2 may predict poor clinical prognosis in patients with GC [36].