Most cancer risk factors were identified in the past decades by specialized epidemiological studies. From global and national statistical evidence the major risk factors of cancer to humans are: Ageing; Tobacco use (active and passive smoking ); Unhealthy Dietary factors; Physical inactivity; Overweight and obesity; Hormones, sexual behaviour; Radiation and sunlight exposure; Alcohol consumption; Chronic inflammation; Occupational carcinogens; Genetic factors. Cancer is the result of accumulation of DNA damage through incomplete repair because of ageing and may lead to mutagenesis and initiation of carcinogenic mechanisms. A paper by Tomasetti and Vogelstein (Science 347:78-81, 2015, from Johns Hopkins University, USA) projected with data the argument that differences in inherent cellular processes (normal stem-cell division in healthy tissue) are the chief reason that some tissues become cancerous more frequently than others. This paper led to assertions that certain forms of cancer are mainly the result of “bad luck”, and suggested that these types would be relatively resistant to prevention efforts. The question of random mutations and “bad luck” on cancer brought the question of prominence of environmental (extrinsic) versus inherited (intrinsic) causes of cancer. Scientists supported until now that environmental factors and lifestyle causes were supposed to be responsible most types of cancer and were preventable through healthier diet style, cessation of smoking and better diagnosis and . The new hypothesis caused many comments and rebuttals by other experts of cancer. Data presented (Wu et al., 2016) argued that the models that were used suggested that mutations during cell division rarely build up to the point of producing cancer, even in tissues with relatively high rates of cell division. In almost all cases, the team found that some exposure to carcinogens or other environmental factors would be needed to trigger disease. This review presents the main arguments supporting “bad luck” and the counter arguments for extrinsic or environmental causes of cancer and comments from well known scientists. Also, the most important causes of cancer, such as diet, tobacco use, obesity, lack of physical activity, alcohol consumption, exposure to sunlight, infectious agents are described with recent literature studies and epidemiological evidence. Additionally, scientific evidence on the campaign “war on cancer” in the developed countries, to diagnose, treat and cure cancer is making steady progress in the last decades.
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