Revisiting the complexity of the ovarian cancer microenvironment--clinical implications for treatment strategies.

Epithelial ovarian cancer (EOC) is the leading cause of death among gynecological malignancies in North American women. Given that EOC encompasses a broad class of tumors consisting of a variety of different histologic and molecular subtypes, which generates genetically and etiologically distinct tumors, several challenges arise during treatment of patients with this disease. Overlaying this complexity is the contribution of supporting cells, particularly stromal components such as fibroblasts and immune infiltrates that collectively create a microenvironment that promotes and enhances cancer progression. A notable example is the induction of angiogenesis, which occurs through the secretion of pro-angiogenic factors by both tumor and tumor-associated cells. The recent development of angiogenic inhibitors targeting tumor vasculature, which have been shown to improve patient outcome when combined with standard therapy, has launched a paradigm shift on how cancer patients should be treated. It is evident that future clinical practices will focus on the incorporation of therapies that antagonize the protumoral effects of such microenvironment contributors. Herein, an overview of the varying tumor-host interactions that influence tumor behavior will be discussed, in addition to the recent efforts undertaken to target these interactions and their potential to revolutionize EOC patient care.