[mft_]

Your impression that chemo is only valuable for metastatic cancer is mistaken.

Chemo is effectively a poison that poisons the tumour faster than the rest of the body; the tumour’s cells are more susceptible to the poison than normal cells because they’re reproducing faster. As such, it doesn’t matter whether the tumour is large or small, localised or metastatic. It’s given systemically simply because of the nature of the drugs in question - because that’s generally how we get drugs into the body. Local administration of drugs is rare, and chemo especially so.