The colored light therapy used by Dinshah has so far been very effective
for cancer pain for me.   The other suggestions on this list are also good.
Did anyone mention zappers or the Beck protocol?  I use a Croft zapper and
the Beck unit--both are very good.  I still have the cancer but feel better
than I ever have in my life nearly all the time.  There are many things that
are just wonderful.  Best wishes to your Mother!!   pj