The role of inflammation in tumor progression: Targeting tumor-associated macrophages

Current evidence suggests an increasing role for inflammation as a critical link to tumor progression. The host response to a cancer shares many parallels with an infection or a wound. Thus it is not surprising that many tumors arise from areas of infection or chronic inflammation. Tumors have been described as wounds that never heal. The local production of cytokines, including chemokines not only attracts circulating immune cells, but also activates stromal cells in the surrounding microenvironment. Of particular interest are tumor-associated macrophages (TAM). The infiltration of tumors with TAM has been shown to correlate with poor prognosis in several cancers. Recent studies suggest an emerging role for TAM in the remodeling of the tumor microenvironment to support growth and metastasis and support the concept of modifying TAM's responses as novel therapeutic approaches. In this review, we will discuss our current understanding of the role of macrophages, and inflammation in the progression to malignant disease and possibilities for development of better therapeutics for the treatment and perhaps prevention of malignancies.