When do cancers produce metastases?
Before producing metastases a normal cell should change itself to a malignant cell. This is explained by the multiple hit theory. When a cell becomes malignant it looses its ability to control its growth and proliferation. So it produces a group of cells which are loosely adhered to each other. So one of these cells can get detached from the original location and can get deposited in a different location. But this is not enough to produce metastases. It should fulfill another need. The malignant cells should acquire the ability to grow in the new location. Since the original malignant cell has undergone significant DNA damage its DNA is unstable. So it undergoes further mutations. During this process one of the cells acquire the ability to grow in a remote location. Now this cell can proliferate, spread ad produce metastases. With further mutations metastasis potential of these cells also increase.
Metastases can occur in different ways,
- Lymphatogenous metastasis
- Hematogenous metastasis
- Metastasis in body cavities
Dormancy of metastases
Some metastasis can remain dormant for some time and later proliferate. This is seen in breast cancers. So when we take all these things into account we should treat cancers as early as possible when the metastatic potential is low.