What is cancer?

In fact you can not speak of a single disease called cancer, but of different types of diseases that have different causes and different, which affect different organs and tissues, which therefore require special diagnostic tests and therapeutic solutions. But there are some properties that are common to all cancers, and which allow some groped a valid response for all forms of the disease. To use a metaphor, one can say that at some point, a cell of the organism, "crazy" - loses some of its properties, it acquires other - and begins to multiply out of every rule.
Metastasis
Within each cell there are in fact of "genes controllers" for a cell to prevent "wrong" to survive. Because the tumor process should be triggered that these "controllers" are out of order. Because of this "failure" in the mechanism that controls the replication, the cells divide and when they should not generate a huge number of other cells with the same lack of control. Healthy cells thus end up being supplanted by the most exuberant tumor cells.
Both cells of a benign tumor of a malignant tumor that those tend to proliferate in an abnormal but, and this is the key difference, only the cells of a malignant tumor - following further amendments borne genes - tend to come off, to invade surrounding tissues, to migrate by the WTO membership to go to colonize other areas of the body. The benign tumor is therefore limited to the body in which it developed, while the malignant tumor - during a process that can be long lasting and extremely variable, however, years - the disease spreads to other organs, and compromise to strike vital organs such as lung, liver, brain. This process is called metastasis and metastases represent the most advanced stage of tumor progression, providing the real cause of cancer deaths.
Genetic mutations
We now know with some certainty that cancer arises from an accumulation of mutations, ie alterations of genes that regulate proliferation and survival of cells, their membership and their mobility. Mutations can develop in very different times, even under the influence of external stimuli. The benign tumor can be considered the first stage of these changes. However, very often, this step is skipped and you get to malignancy without obvious precursors.
What, however, the causes of genetic mutation? Today scientists know that only in rare cases the causes are necessary and sufficient for the development of cancer are already "written" at the origin in genes that are inherited.
Other causes
In the vast majority of tumors, however, alterations of genes that are responsible for the disease are determined by environmental causes. They are caused by prolonged exposure to carcinogens, the chemical, physical or viral infection. However, cigarette smoke, asbestos, certain substances developed by the combustion of coal or oil, alcohol, an unbalanced diet, the sun's ultraviolet rays, chemicals that can be placed on the workers in certain industrial processes or in agriculture, can add up to a "fragile" and arrive at predetermined genetic mutations that cause the - at the same doses and durations of exposure - not found in other individuals.
The answer of science
To deal with this type of problem has developed an enormous amount of laboratory work to study the DNA and the genetic components that affect the increased susceptibility to tumor development.But there is a specific science - epidemiology - whose objective is to identify the causes of cancer and associated risk factors. It is through their identification that can be put into practice that prevention is one of the most important goals to get to the defeat of cancer. Or, rather, the different types of cancer.