Question: Hi. How do normal cells turn into cancer cells in the first place? How do cancer cells even start to be produced in your body?

Alexis Barr answered on 17 Jun 2013:

Normal cells can turn into cancer cells because of mutations in their DNA. If the mutation is in a gene that controls cell reproduction, then a normal cell will start to reproduce out of control. Usually it takes more than one mutation to make a cell reproduce out of control.
When cells reproduce they have to make a copy all of their DNA so that there are now two copies – one for each of the two new cells. In cancer cells, because of mutations in their DNA, the cells can get sloppy about reproducing their DNA which can make even more mutations and make the cancer cells reproduce even more.