For cancer to build up, all cells need more than the opportunity to divide and grow uncontrollably. Non-cancerous, benign tumors also undergo that process. What is ultimately crucial is their ability to invade outside their localized area. Cellular structure in any given area are tightly attached to each other, forming a natural guard against invasion. So to get a cell to break outside of its own area and into another area requires special qualities.

One important thing being studied now when it comes to cancer is always that tight cell connection. There is a kind of special "glue" called the extracellular matrix which holds cells together. If a cell has a substance that can dissolve or consume the "glue", it will have a much better chance of getting out of its area and into another.

The capability of a cancer cell to invade may be caused by several factors. One of these brilliant is the ability to release a protein, known as metalloproteinase that functions to dictate the cell connections not to adhere to each other so tightly. Then the other cells behave in a way that allows the cancer cell to escape its territory and invade. Another possibility is that the cancer cell may be able to push its way out of the tight cell connection on its own. There are a lot of ways this might happen. In the long run, that is good because there are a lot of potential ways to interfere with this process. The down side to this of it is, it's difficult within the short run because this makes these complicated to determine.

While using discovery of cancer genes came a new way of thinking about breast cancer. The astonishing part of it is that all these years, cancer cells have been studied by looking at them in isolation. Medical scientists take cancer cells and grow them in petri dishes and then study their behavior. This is like placing criminals in isolation chambers and then studying their personalities. They are not interacting with anyone, so there actually is no way to examine how they behave. We have finally realized that if we were to study cancer cells seriously in their own environment we can learn much more, because they interact because of their surrounding cells and the surrounding cells have an impact on them.