Hi Rosi,
If you use the search forum function at the top of the page and enter cannabis oil it will throw up all of the discussions here on the site regarding cannabis oil. I just did a search and there were 29 posts on that issue for you to search through. I’d post a link to the search results but for some reason when I do that and link to it the link does not work. But if you do the search yourself it will work for you.
Good luck with this for your brother and please let us know how things go. And hopefully others will chime as well here with their thoughts and experiences to share with you as well. Has your brother spoken to his Onc about this also?
My best to you and your brother,
Gavin