Background and purpose: Cancer is a noteworthy cause of morbidity and mortality worldwide, especially in developing countries. It is more often caused by the environment of a person lives in, rather than his or her innate biology. The highly significant and rapid changes in cancer incidence in the last decades are generally attributed to equally dramatic changes in population exposure to environmental factors.

Methods: The available evidence on the role of environmental factors and their relevant effects in cancer rates has been studied.

Results: Major of cancer risk factors are include tobacco, overweight and obesity, physical activity, diet and body composition, food, air and water contamination, and viral chronic infections. Exposure assessment and research methodology has been the Achilles heel for studies on environmental contaminants and cancer. Thus, it should not be looked at cancer merely as a disease, since cancer is beyond a disease and must be considered through different aspects.

Conclusion: The scientific community effort to increase public awareness, winning the support of policy makers as well as intersectoral coordination in order to lifestyle modifications, reducing high-risk behaviors and confronting food, air and water contamination have strategic importance in cancer prevention. Basic and clinical studies as well as interdisciplinary research thence are necessary for a better understanding of the pathophysiology and finding more effective and cheaper ways to prevent, early diagnosis and treatment of cancer. Accordingly, this requires the investment of governmental and non-governmental democrats.