How Cancer Spreads: Metastasis

Metastasis is the spread of cancer cells from the original tumor to other parts of the body. It is a key step in cancer progression and helps explain why cancer can become more difficult to treat.

Metastasis is a multi-step process, where the tumor cells overcome several challenges to spread from the primary site to form secondary tumors in the body. As few as one  in a million cells manage to achieve metastasis.

Normal cells are confined to their tissue of origin by cell-cell adhesion and the basement membrane, which is a physical...