[Iv]

Considering that chemotherapy is basically feeding poison to your organism in the hope that cancer cells (which are more active) will ingest it in higher quantity, I'd say that we have a pretty high tolerance threshold in term of side-effects while we are looking for an alternative.

[suddenseizure]

As I understand it, most chemotherapy targets only dividing cells. In adult humans there are relatively few of these: cancer cells (which you want to kill), bone marrow (produces blood cells, so you have to monitor blood cell counts during chemo), and reproductive organs (produce gametes, so you may want to freeze sperm/eggs before chemo).