Helicobacter pylori (H. pylori) has been implicated in colorectal carcinogenesis. Here, the association of immune responses to bacterial exposure with advancing stages of colorectal neoplasia was assessed by multiplex serology. Immunoglobulin (Ig) A and G antibody responses to thirteen proteins of H. pylori were measured by a Luminex-based multiplex assay in plasma from patients with colorectal cancer (CRC, n = 25), advanced adenoma (n = 82), or small polyps (n = 85) and controls (n = …