**7. Factors associated with carcinogenesis**

The accumulation of various genetic abnormalities in normal cells causes carcinogenesis. Some cancers are caused by congenital genetic abnormalities, but most genetic abnormalities causing cancers are acquired abnormalities. It is estimated that smoking contributes to 20% of cancers and 23% of cancer deaths and infection with helicobacter pylori, hepatitis virus, etc. contributes to 21% of cancers and 22% of cancer deaths in Japanese population, and these are thought to be the main risk factors for cancer in Japanese population. Drinking alcohol contributes to 6% of both cancers and cancer deaths, and it is also a significant risk factor for cancer in Japanese population. Consumption of salt more than 6 g per day, deficiency of fruit intake, and deficiency of vegetable intake also contribute to 1.6, 0.7, and 0.6% of cancers and 1.4, 0.8, and 0.6% of cancer deaths, respectively [48]. Diet and nutrition seem to have some effects on the development of cancer and cancer mortality.
