Technically you could make cancer extremely unlikely by using the likes of CRISPR to modify our DNA at fertilization. Animals such as Elephants and Whales rarely get cancers regardless of their massive sizes (=larger amounts of cells=Larger risk of damage to genome)

This is due to the fact that they've got more "safety systems" in their cells than we have. More specifically, they've got more copies of the same system we use!

In theory we could implement more copies of the "safety systems" to our DNA to mimic that of the big mammals and in turn practically "cure" cancer by preventing it from ever happening. 

The thing holding us back in this regard is more the ethical part than the scientific from my understanding but I could be wrong!