Cancer isn't about a person deserving it. It strikes people regardless of how good or bad they are. To wish it upon a political enemy is puts you on the same level as people like Ivins. I doubt you really want to share that space with her.
Remember the mast things said about Laura Ingram? Don't lower yourselves to that standard of behavior. Rise above it and wish Ivins well despite her nasty demeanor.
mast = nasty