So it would not be a good idea for a person to ingest cannabis oil if they happen to be TH2 dominant like 96% of cancer patients?
Th1 is considered more helpful in cancer, but as far as I am aware, the Th1 / Th2 balance does not play a major role in cancer (but I don't really have much knowledge in this area).
So in taking Cannabis oil for cancer, you would have to decide whether the anti-cancer effects of THC and CBD outweigh the (likely slight) shift to Th2 that these compounds cause. I would guess that in cancers which are susceptible to Cannabis (types of brain cancers and breast cancers are susceptible), the anti-cancer effects of Cannabis would likely far outweigh any problems a shift to Th2 might produce.
In any case, there are many supplements which shift the immune response to Th1 (such as those listed in
this post), so you could probably easy compensate for any Th2 shift Cannabis causes by taking a few of these Th1 boosters along with Cannabis oil.