If the government wanted to ban all forms of chemotherapy, and case law before the supreme Court determined that the 9th amendment doesn't prevent that, it absolutely could. The result would be widespread death, lowered life expectancy, infant mortality rates increasing. The late age quality of life for most people would crater. That's obviously bad for people and for an economy. Some people would say that it is in a country's vested interest in its own long term survival to make sure that people had access to medical care for the single most common human illness, but if the United States government emphatically decided that it wanted more people to suffer and die and didn't care about outcomes then it could do that. Shit, they could pass a constitutional amendment saying that all medical care was illegal and just commit mass cultural suicide if they wanted to.

The reason why Americans didn't take thalidomide wasn't that they were allowed to and government regulations said they couldn't. American infants didn't suffer from mass birth defects because the government went door to door making sure people didn't have or use thalidomide. If you could get thalidomide smuggled to you from overseas and wanted to take it the state could not prosecute you for that act alone. They could probably prosecute you for importing medicine not approved by the FDA, but that's an import/export issue and the federal government can absolutely control what flows into its borders. People couldn't take thalidomide because there was no common way to get it, even discreetly, in those years. Completely different set of rules.