Important- Gene therapy drug

Can we form a preventative measure drug with some form of gene therapy by knowing the cancer gene (the common denominator gene/s in all cancers)? 

I remembered a stolen idea with this, I think genes have back up genes that do the same job, problem solving on ageing and on how function seems to decrease when genetic damage increases lead to this hypothesis. 

This drug will help us not have to 

Produce as much of the cancer locker drug. This preventetive measure against cancer along with the locker will save a lot of lives I hope. Cancers days are numbered.

Damion