Tumor macrophages protective and pathogenic roles in cancer development.

Macrophage infiltration often occurs in cancer and has stimulated new efforts to define macrophage function within solid tumors. The macrophage, a myelophagocytic cell of the immune system, is at the front line of pathogen defense, wound healing, and maintaining homeostasis within the body. However, increased macrophage numbers during cancer generally correlates with poor prognosis. This chapter will focus on the function of myelophagocytic cells within solid tumors, their potential roles in tumor progression, and the possibilities of their manipulation as a component of cancer therapy.