According to one of our doctors (the senior author on that paper Gary cites) there are some oral cancers that are related to a (human) gene which suppresses the cellular repair mechanism. People with this genetic mutation are more suspectible to oral cancer, it is rather like the women who are pre-disposed to breast or ovarian cancer -- and is a small minority. Whether it is sufficent in and of itself to cause oral cancer, or just makes one more susceptible, I am not sure.

Most of the genetic changes leading to cancer arise from mutations at the cellular level which reduce the ability of the cell to repair itself, and are often preceded by inflammation. A Hopkins doctor studying prostate cancer, Bill Nelson, is elucidating the cascade of events starting with local infection and inflammation and leading to pre-cancerous changes (the "genetic progression model" the article refers to). Nelson has found that at some point in this progression the normal cell loses the ability to repair damage to its genetic material and also, its naturally programmed cell death.

The genetic changes found in oral canacer may come from exposure to carcinogens (e.g. smoking) or in many cases, viral infection. In the latter case the viral genome may be actually incorporated into that of the cell (although not always).

Gail