Cancer Metastasis
The process by which tumor cells from my primary site invade other parts of the body is called metastasis. Metastasis is the fundamental difference between a benign or malignant growth and represents the major clinical problem of cancer. A primary tumor can be surgically removed relatively easily. Unfortunately, many solid tumors have initiated metastasis at the time of diagnosis, and not all can be removed at the time of surgery.
How does the tumor spread?
From next-generation molecular genetic sequencing, we have learned that metastasis from a primary tumor is not clonal. Many clones differ by mutations obtained through an ongoing evolutionary process. We now know that metastasis can be seeded not only from cells of the primary tumor but also from other areas of metastasis.
Tumor cells undergo several steps during metastasis. These include invasion, transport, and metastatic colonization. The individual tumor cells in the tumor microenvironment play a role in the process of metastasis. We now know that loss of suppressor genes such as P 53, which suppresses metastasis, occurs in most cancers. At present, approximately 23 metastasis suppressor genes have been identified. We now know that through the process of angiogenesis which is new blood vessel growth facilitates tumor growth and aggressiveness. These include factors such as vascular endothelial growth factor is occurring (VEGF). When it is turned on and upregulated, it means new blood vessel growth around the cancer is occurring. This pathway can then be turned off and down regulated. Of great importance is the mesenchymal epithelioid transition factor, also known as MET. There is now evidence that inhibiting this pathway can induce suppression.