Table 1.

Strategies for characterizing the pre-metastatic niche and metastasis formation

Strategy	Advantages	Disadvantages
Biomaterial pre-metastatic niche mimic	Limits off-target effects Defined location for analysis Biomaterial properties can be manipulated for different applications Ease of evaluating multiple niche cues in one device Large number of cells can be retrieved from the device	Does not recapitulate all elements of native pre-metastatic niche Foreign body response may influence the biomaterial environment and differ from a natural pre-metastatic niche
High risk tissue bed biopsy	Enables determination of cues leading to organ-specific metastasis Captures heterogeneity between metastatic foci	Variability between samples may confound discovery of critical signals Identification pre-metastatic sites is limited
Tumour cell modification	Direct evidence for molecular drivers of metastasis User-defined alterations	Potential for off target effects on tumour progression Generating a reliable cell/mouse model is challenging
Genetically engineered mouse models (GEMM)	Direct evidence for role of a factor or cell type in metastasis Ability to knock-out and knock-in specific genes	Costly and time-intensive Potential for off-target effects on health of the animal or tumour progression