It’s not changing your dna but it is using your cell machinery to produce proteins, what is DNA really doing if not that? How long before chemotherapy is produc

It’s not changing your dna but it is using your cell machinery to produce proteins, what is DNA really doing if not that? How long before chemotherapy is produced in your own cells by a genetically modified virus that only infects cancerous tissues. I’m only thinking out loud on this and happy to clarify be told I’m wrong.