Abstract
Recent studies delineate a predominant role for the tumor microenvironment in tumor growth and progression. Improved knowledge of cancer biology and investigation of the complex functional interrelation between the cellular and noncellular compartments of the tumor microenvironment have provided an ideal platform for the evolution of novel cancer nanotherapies. In addition, multifunctional "smart" nanoparticles carrying imaging agents and delivering multiple drugs targeted preferentially to the tumor/tumor microenvironment will lead to early diagnosis and better treatment for patients with cancer. The emerging knowledge of the tumor microenvironment has enabled rational designing of nanoparticles for combinatorial treatment strategies that include radiotherapy, antiangiogenesis and chemotherapy. This multimodality approach is thus expected to achieve therapeutic efficacy and enhance the quality of life of cancer patients. This review highlights the unique characteristics of the tumor microenvironment that are exploited by nanotechnology to develop novel drug delivery systems aimed to target the tumor/tumor microenvironment.