Sadly, the SELECT study you link to does not mention which vitamin E was used. There are several variations (tocopherol alpha-through-delta and tocotrienol alpha-through-delta), not to mention isomers.

There have been some (mostly in vitro) studies showing delta-tocotrienols ability to induce apoptosis in cancer cells. For example: https://pubmed.ncbi.nlm.nih.gov/30719778/

I'd expect that there's a 'natural experiment' out there as there are tocotrienols in red palm oil - and that oil is part of a traditional Nigerian diet (probably other places, but that's the one I know of)