From primary to secondary cancer formation - models for disseminating cancer cells

Disseminated tumor cells (DTCs) are considered to be the potential metastasis initiating cells. Elucidating the biology of DTCs promises a better understanding of metastasis and might enable more effective therapies to tackle metastasis. Unfortunately, DTCs are very difficult to trace in cancer patients constraining their comprehensive biologic characterization. Therefore, non-human in vivo models are needed to replicate the complex metastatic cascade to study DTCs in a realistic context. On the basis of two recently published models, we argue here that currently only transgenic mouse cancer models permit such studies.