According to an article publsihed on Huffington Post researches have been working on this since 2007.  The ID-1 Cancer cell helps Cancer cells spread.  A compund found in good ole Mary Jane basically "turns off" the ID-1 cell and heals it back to normal. Human studies are starting soon.  This could mean big things for Weed advocates especially the "medicinal marijuana" movement.  Here are a few paragraphs from the story, you can read the entire article by cliking the link at the bottom. Thought some people might be interested in this.

A pair of scientists at California Pacific Medical Center in San Francisco has found that a compound derived from marijuana could stop metastasis in many kinds of aggressive cancer, potentially altering the fatality of the disease forever.

"What we found was that his Cannabidiol could essentially 'turn off' the ID-1," Desprez told HuffPost. The cells stopped spreading and returned to normal.

Desprez and McAllister first published a paper about the finding in 2007. Since then, their team has found that CBD works both in the lab and in animals. And now, they've found even more good news.

"We started by researching breast cancer," said Desprez. "But now we've found that Cannabidiol works with many kinds of aggressive cancers--brain, prostate--any kind in which these high levels of ID-1 are present."

Desprez hopes that clinical trials will begin immediately.

Check the entire story and links here. http://www.huffingtonpost.com/2012/09/19/marijuana-and-cancer_n_1898208.html