cancer of lymthnodes 3-rd stage

My friend's been diagnosed with lymthnode cancer 7 months ago, has gone a few chemos (I don't know how many and what type of drugs were used? all I know there were about 4 different types)
I suggested a very striced diet to boost the immune system (tured out that the doctors hadn't tell her anything about diet). The latest blood test came with a very low red/white cell count, which resulted in a delay of next chemo.
Any suggestions on what to do, what kind of drugs will more likely to help?
I appreciate any help in advance (if you can, e-mail me).