It's possible that this drug doesn't wipe out all cancer cells if effective, thus leading to the possibility of the cells eventually mutating. But it's not like

It's possible that this drug doesn't wipe out all cancer cells if effective, thus leading to the possibility of the cells eventually mutating. But it's not like cancer is some bacteria that can become universally resistant. The ABVD regime starts with the same baseline on all hodgkin's lymphoma patients, and 'cures' cancer permanently in quite a large number of them.