Dec. 26, 2007 -- THC and another marijuana-derived compound slow the spread of cervical and lung cancers, test-tube studies suggest.

The new findings add to the fast-growing number of animal and cell-culture studies showing different anticancer effects for cannabinoids, chemical compounds derived from marijuana.

Cannabinoids, and sometimes marijuana itself, are currently used to lessen the nausea and pain experienced by many cancer patients. The new findings -- yet to be proven in human studies -- suggest that cannabinoids may have a direct anticancer effect.

"Cannabinoids' ... potential therapeutic benefit in the treatment of highly invasive cancers should be addressed in clinical trials," conclude Robert Ramer, PhD, and Burkhard Hinz, PhD, of the University of Rostock, Germany.

Might cannabinoids keep dangerous tumors from spreading throughout the body? Ramer and Hinz set up an experiment in which invasive cervical and lung cancer cells had make their way through a tissue-like gel. Even at very low concentrations, the marijuana compounds THC and methanandamide (MA) significantly slowed the invading cancer cells.

Doses of THC that reduce pain in cancer patients yield blood concentrations much higherthanthe concentrations needed to inhibit cancer invasion.

"Thus the effects of THC on cell invasion occurred at therapeutically relevant concentrations," Ramer and Hinz note.

The researchers are quick to point out that much more study is needed to find out whether these test-tube results apply to tumor growth in animals and in humans.

Ramer and Hinz report the findings in the Jan. 2, 2008 issue of the Journal of the National Cancer Institute.