It stops the rapid cell division that is characteristic of colorectal cancer, and which allows it to spread, say researchers from Penn State College of Medicine.
"Every time a cell divides there's the chance that it will mutate and keep dividing when it shouldn't, which is how cancers start. So if we can block that signal that's telling cancer cells to continue to divide, then that could be a way to stop that cancer," said researcher Kent Vrana.
Rapid cell division is also characteristic of skin cancer, so there's a possibility that marijuana compounds could be effective against that cancer as well.
The researchers tested different compounds in marijuana on lines of colorectal cancer cells, although the most common—THC and CBD—didn't have any anti-cancer properties. It was 10 other compounds that were the cancer fighters.
In all, the researchers tested 370 cannabinoid compounds.
Colorectal cancer is one of the most common, with more than 140,000 new cases diagnosed annually in the US; around 50,000 Americans die from the cancer every year.