Human cancer is a chronic disease that originates from transformed tumor cells harboring genetic as well as epigenetic alterations. It develops via a multi-step process that can be divided both operationally and mechanistically into three phases: initiation, promotion and progression. However, cancer is not merely an autonomous mass of mutant cells, but is composed of multiple cell types, such as fibroblasts and epithelial cells, innate and adaptive immune cells, and cells forming blood vessels and lymphatic vasculature. A striking feature of many cancers is an underlying persistent and unresolved inflammation, which often orchestrates a tumor supporting microenvironment. Several lines of evidence identified an enhanced expression of S100A8 and S100A9 proteins in pathological conditions of chronic inflammation and inflammation- associated carcinogenesis in patient specimens as well as cell culture and experimental animal models. More recently, the analysis of genetically modified mouse models and cell lines derived thereof has provided important new insights into the regulation and molecular function of S100A8 and S100A9 proteins in vivo and in vitro. In this review, we will summarize our current knowledge on S100A8 and S100A9 regulation and function on tumor cell signaling and survival, as well as the establishment of an inflammatory, pro-tumorigenic microenvironment. Based on this knowledge, this review will discuss potential strategies to interfere with S100A8 and S100A9 function as a novel option to develop innovative strategies for cancer prevention or therapy.