how do cancer cells form… like, how do they get there? are they already present years before??

Question: how do cancer cells form... like, how do they get there? are they already present years before??

Asked by semajt to Jo on 15 Jun 2010 in Categories: Your Research.
- Joanna Watson answered on 15 Jun 2010:
  
  Cancer cells are just normal cells that have problems with their DNA and don’t work properly any more. Some cancers take many years to develop, so yes, there can be cancer cells a long time before a cancer causes any symptoms or is diagnosed.

Question: how do cancer cells form... like, how do they get there? are they already present years before??