The burden of cancer is increasing worldwide, with a continuous rise of the annual total cases. Although mortality rates due to cancer are declining in developed countries, the total number of cancer deaths continues to rise due to the increase in the number of aged people. Three main causes of cancer have been described, represented by environmental factors, hereditary factors and random factors related to defects originated during cell replication. The frequency of cancers is very different for the various tissues and there is great debate on the extent of the specific contribution of environmental factors and random factors (due to "bad luck") to cancer development. However, there is consensus that about 50% of all cases of cancer are related to environment and are preventable. Although a part of cancers is related to intrinsic mechanisms non preventable of genetic instability, it is evident that implementation of primary and secondary prevention measures is the only affordable strategy to meet from a medical and economic point of view the tremendous pressure created on healthcare structures by the increased cancer burden. It is time to bypass the paradox of disease prevention: celebrated in principle, resisted in practice.