. >> like san francisco researchers, pierre and shawn mcalister who said they have seen firsthand what the cannabis compound can do. in their lab, they use cbd to kill mice and human cancer cells. we asked the american cancer society about all of this. in a statement to cnn, they said there's no available scientific evidence from controlled studies in humans that cannabis can cure or treat cancer. even landon's doctor prescribed his marijuana and is a firm believer in marijuana is caution about this. >> she decided to stop the chemo therapy from landon. as a doctor who has seen his progress, is that something you would be on board with that you would recommend? >> as a physician, i'm not sure that i could recommend that to a parent to say, you know, i can't say to them i know that the cbd is a treatment that can work and you don't e need the chemo. >> for time being, she's afraid of losing her son so she's allowing chemo therapy once a month. she's still trying to find an oncologist tlog take landon off the chemo. so far she's had no luck. colorado is one of 20 states plus d.c. that no