- Cannabinoids, like delta-9-tetrahydrocannabinol and cannabidiol (CBD), have the ability to reduce cancer cell viability. Pure CBD was as potent or more potent at reducing cancer cell viability as the most potent oil tested, as tested on 6 cancer cell lines from 3 types of human cancer. https://www.karger.com/article/fulltext/510256 269 comments science