This thesis explores the role of components of the tumor associated stroma, with particular focus on immune cells and their role in propagating cancer progression. Collecting recent developments regarding the function of the tumor stroma with a focus on myeloid-derived suppressor cells (MDSCs) and cancer- associated fibroblasts (CAFs), and an in-depth description of their features and functions is the purpose of this thesis. The therapeutic potential of targeting these cells, highlighting their roles in cancer formation and progression will also be discussed.