In my travels looking at cancer remedies I have not seen/read anything that "contraindicates" olive oil.
Since she is doing this the natural way I would like to point her in the direction of "Dr Kelley" look the name up on the Internet, Google.com. His programme uses detoxification eg Liver Flush and natural remedies/diet to CURE cancer. He uses the same method(very similar) as what Hulda Clark e, ie olive oil. Has apparently cured during his time practicing 33,000 people that stuck to the programme. Note he initially started his programme in 1962 or thereabouts.
Hi have seen good reports about Flaxseed and Emu oil.
Apart from "Dr Kelley's" work the pther promising thing is "vitamin B17"/Amygdalin from Apricot seeds and other sources. My brother to help treat lymphoma used this but he also took chemo. The Lymphoma has not reappeared as yet - 3yrs - and he has also changed his diet dramatically.
My Father-in-law has Prostate cancer and he has opted for the slash/burn/poison technique but has also changed his diet and is starting to exercise (which he hasn't done for the last 20 years). He may have regretted the slash as they did a partial cut and then discovered they didn't get all of it.. so the saga continues.. He doesn't want to listen about the alternatives but his concession was the improvement in diet and exercise..