The oil?
If properly made.
The oil is not only safe, but will help abate the damage that the chemo does by it's very nature.

The chemotherapy?
Oh hell no!

The labels on those meds have warnings for anyone who even has to handle them that scare the shit out of any sane man.
Most are carcinogens!
Says so, right on the label.

But, I would not advise, him to refuse it, because I'm unaware of any oil reported cures of non-smallcell cancers.
There is evidence to support remission of smallcell with oil and chemo, and with oil only.

In short, possible remission aside, the oil is the absolute best anti-nauseant available.
It will help enormously, just by allowing him to eat, and retain enough fuel to stand up to the treatment.

And please, point me at your sources for the conflicting accounts.
There could be some merit.
I'm open to any information.

Alo ha,

Weezard