Metastasis

Overview of the metastases

Most deaths (90%) associated with cancer caused by metastasis of cancer cells home to areas distant from the original tumor or base.  Metastasis is the process by which cancer cells migrate through the body.

For cells moving through the body, they must first pass over or around neighboring cells.  They do it to reorganize their cytoskeleton and to other cells and extracellular matrix proteins in the outer plasma membrane.  By expanding the cell forward and let go at the end, the cells can migrate forward.  The cells can be monitored until they reach a block that can not be reviewed.  Often, this block is a thick layer of proteins and glycoproteins surrounding tissue, called the basal lamina or basal membrane.  Crossing this layer, cancer cells secrete a mixture of digestive enzymes that degrade proteins of the basement membrane and let it slip.

The proteins secreted by cancer cells contain a group of enzymes called matrix metalloproteinase (MMP).  These enzymes act as “molecular scissors” to cut through the proteins that inhibit the movement of migrating cancer cells.  Once the cells have crossed the basal membrane, which can spread through the body in many ways.  You can enter the bloodstream by squeezing between the cells that form blood vessels.

Once in the bloodstream, the cells floating in the bloodstream until they find a suitable place to settle down and go back into the tissue.  The cells can begin to develop in this new location, the formation of a new tumor.

The process of metastasis is highly inefficient, but causes the most deaths related to cancer.  This is because the number of cells that depart a tumor can be millions per day.  Although only a small fraction of cells that deviate a tumor can survive to form a new tumor, the large number of trials which means that the growth gap is likely to sometimes

Migration of cancer cells may die of a variety of reasons, including:

* The cells normally reside close relations with its neighbors and the mesh of proteins around them.  Department of the surface of other cells can lead to cell death (anoikis called “one-oh-e-KUS).
* Cancer cells are often quite large compared with cells that normally live in the lymphatic system or blood.  When traveling through the vessels may be damaged or jammed, leading to cell death.
* Cancer cells can be recognized and destroyed by cells of the immune system

It is also important to note that even if cancer cells do not die, that does not mean it will form a tumor.  Cells can be found in places far from the original tumor, but multiply enough to cause problems.

Prepare the ground for metastases

How primary tumors metastasize?  For primary tumor cells to become metastatic several incidents that occur and the failure of the first step in preventing metastases.  Cancer cells must detach from the primary tumor, increase their motility (movement), enter the circulation, survive transport in the circulation, exit traffic, and successfully colonize a new tissue.  (1) metastasis is extremely inefficient, millions of tumor cells penetrate the blood every day, but only a small fraction ever manage to colonize other tissues.  This suggests that normal tissue is very hostile to the invasion of cells and cancer cells must overcome multiple barriers to successful metastasis.

Cancer cells are very heterogeneous, which means that they contain many types of genetically different cells, each a result of random mutations.  Each cell type has a different metastatic potential.  Studies indicate metastases metastasis Each comes from a single tumor mutations cell.Researchers first thought after the metastatic ability to develop end of life of the primary tumor.  However, recent data suggest that metastatic cells are a component of early cancer, as cells expressing genes required for metastasis can be isolated from early tumors.  In addition, cancer patients at an early stage often have micro (very small metastases that have not yet developed tumors)

Routes of metastasis

There are three main types of tumors can spread to distant organs:

1.  Thanks for the circulation (blood) system (hematogenous)
2.  Through the lymph system
3.  Through the body wall of the abdominal and thoracic cavity (transcoelomic).

The circulatory system is the main route of spread to distant organs, while the lymphatics provide a route to local lymph nodes metastases after often travels through the bloodstream (1) Although the circulatory system appears to be the most common way the extent of lymphatic filariasis spread from hematogenous origin and seems to  to depend on the location of primary tumor.  (2) For example, spreading tumors of bone and soft tissue (sarcomas), mainly through blood, while melanoma, breast, lung and gastrointestinal tumors spread through the lymphatic system.  transcoelomic share (3) is quite rare, and appears to be limited to cases of mesothelioma and ovarian carcinoma (4).

Of tumor cells to gain access to lymphatics or blood vessels, tumors need to promote the growth of these vessels in and around the tumor.  Growth of blood vessels is called angiogenesis and growth of lymphatic vessels is lymphangiogenesis.