That is true for cancers without targeted therapies. But cancers such as CML, breast cancer, melanoma, etc, all now have targeted therapies against specific mol

That is true for cancers without targeted therapies. But cancers such as CML, breast cancer, melanoma, etc, all now have targeted therapies against specific molecules (often tyrosine kinases). While alkylating agents, etc, are still widely used, I think it's fair to say that the future that you have described is the present. We have the better approach, and now it's a matter of aggressively pursuing it (which is also happening).