Elevated levels of circulating C-reactive protein (CRP) are associated with worse outcome for patients with colorectal cancer (CRC). Monomeric CRP (mCRP) has been demonstrated in tissues of various diseases, including colon cancer (CC). mCRP possesses proinflammatory properties and potentially contributes to tumour-promoting inflammation. Although considered tissue-based, mCRP can exist in the circulation bound to membranes or as aggregates. This project aimed to detect and quantify circulating mCRP in CC patients by mass spectrometry.