The sleeping ugly: Tumour microenvironment's act to make or break the spell of dormancy

Metastasis is the main cause of death for most cancer patients. It appears clear from clinical observations that the majority of cancers, particularly carcinoma do not follow a linear model of metastatic progression, where cancer cells shed from the primary tumour, disseminate to a distant organ and immediately outgrow to form clinical metastasis. Certainly, while cancer spreading is an early event, metastasis occurs much later during tumour progression and frequently arises several years after primary tumour resection. The time spent by disseminated cancer cells (DTCs) in a distant organ before their outgrowth is termed metastatic latency. We will examine here the current knowledge of the mechanisms allowing metastatic latency and discuss the crucial role of the DTCs' tissue microenvironment in this process.