There are families who never get cancer. Even family members with long term smoking.
Study those families. What is it in their genetics that make them immune to cancer cells developing?
And what is it in the families genes of the ones who have multiple family members die of the disease?
The answer is there. I think we are just too scared to really look. Then we can start testing babies in the womb and say *look* the have the cancer gene.
What do you do with a child in the womb with the cancer gene?