The uniqueness of tumor/cancer cells

  Seems to me that if a test could be developed to catch early mutations that it could be used to catch cancer before it even starts.  It's not a surprise that the mutations vary from cell to cell and cancer to cancer.  I wouldn't be at all surprised that it's not directly attributable to what caused it hence the wide ranges of mutation types.  A study that isolates a group of people who were exposed to a certain carcinogen to see if the same mutations were occurring would help to prove the connection to a specific environmental cause.