I would add though that I personally had another case of DNA mutation. Of which there is very little known about its origins and causes due to its rarity (no funding goes to the few, mostly to the vast genetic mutations). In my case, I have ACC (adenoid cystic carcinoma). A very rare cancer, with interesting traits. I bring it up only because of what we DO know...it is NOT congenital...but neither is it known why it occurs, but toxicity in the lungs (tobacco, or other chemicals) has been pretty much ruled out as well. It appears to be a sudden drastic mutation of the genetic level of a single cell...
People can live with it for YEARS...literally, without consequence. I apparently had it since I was 5 or 6 (their guess) but it didnt start to show until I was 13...and it wasnt diagnosed until I was 20. Its is VERY slow growing...and causes no pain.
What is interesting though, is that chemotherapy, and radiotherapy have little to no effect on it. Why? Because apparently, unlike popular belief...radiation causes the most damage to a cell, and its DNA when the cell is dividing...our normal body cells (minus nervous system cells) repicate very frequently, radiation to these cells is bad news.
Unlike normal cells though (and just about every other cancer) these cells replicate rarely...the cell walls acting as a protective agent to the cells dna, and other parts of the cell needed to survive....likes its own personal "ozone layer, protecting us from the suns radiation".
Perhaps in the future, this could also be a trait normal cells might pick up on...slower multiplication...if the normal cells in our body dont replicate often...they are MUCH less succeptable to the dangers radiation causes to dna.
(Also, already had the surgery to have it removed...but due to metastasis...it is nearly impossible for the doctors to believe that it is gone for good...and the "new" infected area would not show up for years...a potentially deadly disease...but since it takes so long to develop...not one that is a death sentence any more than old age is.)