Rudolf Virchow postulated that a critical feature of tumors was the presence of leukocytes, providing the first indication that inflammation may play a role in tumorigenesis. We now have a wealth of experimental and clinical data demonstrating a clear relationship between inflammatory responses and the roles they play at different stages of tumor development. The details of the dynamic relationship between tumor cells and specific subtypes of immune cells and mesenchymal cells are being revealed as critical to cancer progression which has led to the development of potential new targets for cancer treatment. This review describes some of the key molecular and cellular events demonstrating the critical role of inflammation on promoting tumorigenesis with attention on novel therapeutics and their potential clinical success.