I don't know any "wonder" herbs, but I know about one with relatively reasonable hope. It is a Hungarian product called "Avemar" distributed in the US under the name of "Ave". It is a fermented wheat germ extract. (Pretty expensive.)
I am taking it currently (tastes horrible, but it is once a day), and - to my surprise - yesterday my oncologist (Lombardi Cancer Center, Washington, DC) did not object taking it during chemo. (I have Stage IV, SCC.) Furthermore, he mentioned that he thinks it is really promising. (I did not talk to my radiologist yet - he may flatly reject it during radiation.)
I am not aware of any recommendation taking "Ave" instead of chemo - it is recommended taking it *with* and *after* chemo. But, if you father refuses chemo, this may be better than nothing.
You can find a bunch of peer-reviewed articles at this URL (most in English, some in Hungarian):
http://www.avemar.com/avemar_references.php
Good luck to your father,
Laszlo