Most cancers are associated with aging. The longer a person lives, the more likely it is that cancer causing lesions accumulate in their cells. It is estimated that more than 40 percent of all new cancer cases could be avoided by changing the risk factors which individuals can influence. The single biggest risk factor is smoking, which explains even up to 20% of all new cancer cases.
The developing of cancer is a series of events over a period of many years, during which originally healthy genetic cell material is damaged and the cells change through a number of intermediate stages of the body into tissue independent of the body’s regulatory systems. As it grows, the malignant tissue eventually causes symptoms.See an animation of the initiation of the cancer process.
In the majority of cancer cases the specific cause of the disease cannot be identified.