Robert Ramer and Burkhard Hinz of the University of Rostock, in Germany, investigated whether and by what mechanism cannabinoids inhibit tumor cell invasion.

The study, published in the Journal of the National Cancer Institute, found cannabinoids did suppress tumor cell invasion and stimulated the expression of TIMP-1, an inhibitor of a group of enzymes that are involved in tumor cell invasion.

"To our knowledge, this is the first report of TIMP-1-dependent anti-invasive effects of cannabinoids," the study authors say in an statement. "This signaling pathway may play an important role in the anti-metastatic action of cannabinoids, whose potential therapeutic benefit in the treatment of highly invasive cancers should be addressed in clinical trials."