摘要
The mechanism of cancer metastasis is far more complex than the mere mechanical shedding of tumor cells into the circulation,followed by cell proliferation within an organ where they accidentally get lodged.Metastatic spread is also not random;different primary tumors exhibit predilections for specific organs they metastasize to.This notion dates back to 1889 when Stephen Paget described the“seed and soil”hypothesis,suggesting that the spread of tumor cells is governed by close interactions between specific cancer cells(seed)and the host organ(soil).Other crucial processes of metastatic spread,such as cell intravasation,extravasation,tumor latency,metastatic niche formation,and the development of micrometastasis and macrometastasis,have been delineated over the last few decades.
