ERBB2 and carcinoma: Proximal carcinomas are more often mucinous and microsatellite unstable high, whereas distal carcinomas are more frequently human epidermal growth factor receptor 2 amplified and chromosome unstable.54 Concomitant with increased access to the mucosal epithelium, the microbial community forms a bacterial biofilm shown to be particularly present in the proximal colon.55 The direct bacterial contact with epithelial cells could result in perturbed epithelial function and chronic inflammation, thereby predisposing to proximal colon pathogenesis.