ABSTRACT
Cancer is one of the main reasons of mortality worldwide, and more than 90 percent of cancer deaths are due to metastasis. Although primary tumors are curable using chemical adjuvant therapy or surgery, metastatic tumors are mostly incurable. This resistance shows the high rate of mortality among patients with metastatic disease. Being a sequential event, metastasis is a subtle and intricate process in which tumor cells undergo a plenty of changes and acquire the capacity of migration, invasion, survival and self-renewal which all are necessary for metastasis to happen. The key point in recognition and cure in invasive cancers is to identify critical genes, proteins and pathways involved, and show their relation with each other and the disease. Forming metastasis needs favorable genetic and microenvironmental elements of tumor cells and distant tissue, respectively. Unfavorable conditions in each steps of this process lead to arresting metastasis and subsequent dormancy, which is the most important phenomenon in relapse. In this review, benefiting from tens of reliable and recently identified data and personal experiences, it has been tried to draw new patterns associated with metastasis for further investigation. Determining genes, proteins and microenvironmental factors that affect metastasis, in a sequential manner, can help better understanding of this lethal process and subsequently a prosperous treatment