Environmental causes of cancer

The development of cancer in an individual is the result of multiple genetic and epigenetic steps. Carcinogens and tumor promoters can act by a variety of molecular mechanisms, and repeated exposure to numerous agents is frequently necessary for the formation of cancer. The estimate of cancer risk in a population is performed via a formal quantitative risk assessment. The estimated risk in an individual is more complex because of both inherited predispositions and lifestyle. Although information is available, it is essential to understand the goals, attributes, and limitations of the experimental methods underlying our current understanding of the environmental causes of cancer.