As outlined in the Understanding Cancer section, the transformation of normal cells into cancerous tumors may be caused by insults or "hits" to the cell's genetic structure. These hits—a combination of genetics, environmental factors and especially lifestyle habits—interact and accumulate over time.
There are hits that initiate cancer— tobacco smoke, x-rays, certain hormones and drugs, sunlight, industrial chemicals and some sexually transmitted viruses.
And there are promoters such as alcohol and stress. It takes at least one or two hits to damage a cell and affect the DNA. As the hits accumulate, a breaking point is eventually reached and a normal cell mutates, changing into a cell that grows uncontrollably—a cancer cell.
We can do nothing about some risk factors . But most are a matter of choice.
Heredity When there is a family predisposition to cancer, heredity may be the first event that promotes the growth of cancer. A cell may then be changed into a cancer cell by a single hit of a carcinogen. Although a tendency or susceptibility to developing cancer can be inherited under certain conditions, probably less than 2 percent of malignancies are caused directly by heredity. The vast majority of family histories of cancer result from a complex interaction of genes, environment and lifestyle.
Geographic Area People living in areas where there are vitamin or mineral deficiencies such as selenium deficiency may run a higher risk of cancer. The biggest influence of geographic area, however, is on diet, which may also be influenced by cultural habits.
