Chemotherapy for the Soul

The weird thing about some medicines is how sick they make you in the process of rendering you well...

Chemotherapy - the use of toxic materials to kill cells en masse. At times the cure seems worse than the disease but then one day, the cancer just stops and the body can then begin to renew itself and here's to a healthy and hopeful future.
This is all true for sickness and disease but what about the people that we know?

If a person can be a cancer on your soul - a persistent stain, multiplying and growing until you feel you'll be eaten from within by having been merely exposed to their existence - why can't a person be the chemotherapy. The one that makes it all goes away, but yet manages to simultaneously lay waste to everything in its path.
True, feeling better and having all memory of the original stain wiped clean, but in the aftermath you realize that while not as indelible as the last person, the chemotherapy creature had the same effect on your state of mind as napalm on a field of vegetation.

Perhaps it's just not chemo at all, but rather methadone for heroin. It's just another bad thing for a bad thing. Substituting one pain for another...
But then again it may be all in the head - a result of being conditioned to think that nothing is right unless something is wrong.