Figure 2.

Allocation of the main study focus according to the corresponding step of multistep cascade of metastasis. Only studies listed in Table 1 of this review were included. Steps were defined as follows: 1. Primary tumor, 2. Premetastatic niche pre-colonization, 3. Local invasion and intravasation, 4. Circulation, dissemination and survival, 5. Adherence and arrest in a new organ, 6. Extravasation into the surrounding tissue, 7. Initiation and maintenance of growth and vascularization [9,10,11,46,47].