Hahaha, I can just see the fundo-conservatives' reaction: Cancer cure from Clone souls is evil!

...'cause every clone is sacred, every clone is great,
If a clone is wasted, God gets quite irate.
After all, they do oppose stem cell research... I'll be surprised if they don't go to the fricking barricades against this.

Then again, perhaps they could take a reasonable approach on this matter.
By the way... if there were more radiation, the specimen prone to cancer would die out before getting a chance to reproduce, and the rest of the population would eventually develope more or less similar ways to fix radiation-induced cell damage like
Deinococcus radiodurans has. Of course, too much radiation and it'll just kill the species out - along with a few others on the way - but it might be interesting (if a slightly inhumane) experience to separate a population of humans in a town and increase their radiation exposure generation by generation, until they were fit for interstellar traveling without significant radiation shielding...

or nuclear reactor chamber maintenance crews.
I would offer a cookie for every unethical idea or implication in that, but I'd probably run out of them.
....soo.. where was it. Right. Cancer. Carry on...