It sounds like she zapped long enough to be rid of the cancer carrying flukes. As long as she keeps those gone, she should stay cancer-free. :)
And I completely understand loved ones not wanting to do stuff that tastes bad or is inconvenient. My guy's the very same, but fortunately has the constitution of an ox, for the most part. And of course, inevitably it's me pushing for him to address minor health issues before they become major.
I personally have had that one dang thing after another since I hit my 30's. Never anything as severe as cancer, which showed up after I quit zapping in my late fifties. But it was usually painful, no matter what, so I was always quite motivated to fix it. :)
I'm not too surprised her wrist hurt when zapping though. I'd suspect it was killing parasites in her wrist, and those dead parasites's infections had to move to a still living host---your wife. And that was the cause of the pain, not zapping. Which also means your wife is probably on track for 'arthritis', the name given to that group of parasite symptoms as they would surely spread up into her hands. :(
Most parasites are infected with some pathogen, which is causing most of the pain, and that's what the Black-Walnut hull was for--to kill infections. I personally found 3 other herbs that did a better job, though. But she might want to reconsider and zap at least once a week, if for no reason than to make sure the cancer carrying flukes are killed and she doesn't end up with arthritis. :)