Is it possible to cure gut worms in Rimworld?

Yes. There are two ways to do this.

Gut worms will eventually go away with repeated treatment. This requires a total of 300% treament quality. For example, 3 treatments of 100% quality, or 6 treatments of 50% quality.

Alternatively, you can amputate the colonist's stomach. This will remove the worms. A colonist can survive without a stomach, but they will eat extremely slowly as a result. You can't transplant stomachs but you can craft or buy a bionic replacement.