Most of the evidence indicates that cancer formation is a process requiring the exercise of multilevel latent duration, called the theory of the initiation-promotion in carcinogenesis. Cancer cells are formed from normal cells in a complex process called transformation. Consist of two stages of initiation and promotion.
Initiation-promotion theory states that the first step in carcinogenesis is a mutation of the DNA of living cells during DNA transcription. So that cancer can be generated from this initial event or mutation of this settlement, there should be an interaction that lasted longer for those cells with various substances promoter. Promoter substances are substances that stimulate reproduction and cell division. So many causes of initiation, the presence of various promoters, factors of heredity, age, and environment. All of it plays a role in cancer formation.
At the initiation stage or the introduction of certain permanent changes occur sutau genetic material of cells in the cell would be a dangerous lure.
Changes in the cell's genetic material is caused by an agent called a carcinogen, which can include chemicals, viruses, radiation, or ultraviolet rays of the sun. However, not all cells have the same sensitivity to a carcinogen.
Promotion is the process of induction of tumors in cells that had previously been initiated or induced by chemicals. Even chronic physical disorders were biased making cells more sensitive to experience a hazard. In promotion fase, a cell that has undergone the initiation will become dangerous. Cells that have not passed the initiation stage will not be affected by the campaign. Because it may take several factors for occurrence of harmful cells (combined from sensitive cells and a carcinogen).
In a process in which a normal cell be a dangerous cells, ultimately gene DNA (desoksiribonukleik acid) from the cell will experience changes. Changes in the genetic material of cells is often difficult to find, but the occurrence of cancer can sometimes be known from the existence of a change in size or shape of one particular chromosome. The more often splits and transcribed DNA, the greater the likelihood of an error. And undetectable errors will mutate and inherited. For example, an abnormal chromosome called the Philadelphia chromosome is found in approximately 80% of patients with chronic myelogenous leukemia blood cancer.