Each time a body cell divides, the DNA must be replicated, so that each daughter cell receives a complete copy of the genetic material. Mistakes can and do occur during the DNA replication process. Most mistakes are corrected, but occasional mistakes slip past the cell's 'proof-reading' mechanisms, resulting in mutation. Certain agents can damage DNA, or interfere with accurate replication of DNA, increasing the likelihood of mutation. A risk factor is any characteristic associated with an increased likelihood of developing a disease.
Risk factors are different for different types of cancer.
Although the relationship between specific risk factors and acquired gene mutations is not always clear, risk factors are thought to increase the likelihood of cancer by increasing the likelihood of DNA damage. People with no known risk factors develop cancer. In general, however, cancer is more likely to develop in an individual with risk factors, than in an individual without risk factors. Different types of cancer are associated with different sets of risk factors. Other cancers are more common in women.