WASHINGTON (Reuters) - A leading U.S. doctors group has endorsed using marijuana for medical purposes, urging the government to roll back a prohibition on using it to treat patients and supporting studies into its medical applications.

Medical marijuana is displayed in Los Angeles August 6, 2007. A leading U.S. doctors group has endorsed using marijuana for medical purposes, urging the government to roll back a prohibition on using it to treat patients and supporting studies into its medical applications. REUTERS/Mario Anzuoni

The American College of Physicians, the second-largest doctors group in the United States, issued a policy statement on medical marijuana this week after it was approved by its governing body, the group said on Friday.

The group cited evidence that marijuana is valuable in treating severe weight loss associated with AIDS, and nausea and vomiting associated with chemotherapy in cancer patients.

“Additional research is needed to clarify marijuana’s therapeutic properties and determine standard and optimal doses and routes of delivery. Unfortunately, research expansion has been hindered by a complicated federal approval process, limited availability of research-grade marijuana and the debate over legalization,” the group said.

The Philadelphia-based group, founded in 1915, is made up of 124,000 doctors who treat adults.

“The richness of modern medicine is to carefully evaluate new treatments. Marijuana has been in a special category because of, I suppose, its abuses and other concerns,” Dr. David Dale, the group’s president and a University of Washington professor of medicine, said in a phone interview.

‘SCIENCE SHOULD BE KEPT OPEN’

David Murray, the White House Office of National Drug Control Policy’s chief scientist, said, “The science should be kept open. There should be more research. We should continue to investigate.”

The policy statement said, “ACP encourages the use of nonsmoked forms of THC (the main psychoactive element in marijuana) that have proven therapeutic value.” It also backed research into additional therapeutic uses of marijuana.

The government should review marijuana’s status as a so-called schedule I controlled substance, alongside such drugs as LSD and heroin, given scientific evidence of its safety and efficacy for some medical conditions, the doctors group said.

It called for exempting doctors who prescribe or dispense medical marijuana in accordance with state law from federal criminal prosecution and other actions. It also urged protection from criminal penalties for patients who use medical marijuana as permitted under state laws.

A dozen states have laws allowing the use of marijuana for medical purposes. But supporters of medical marijuana accuse the federal government of undermining those state laws by having Drug Enforcement Administration agents raid medical marijuana providers.

Rob Kampia, executive director of the Marijuana Policy Project, which urges legal and regulated sales of marijuana, said, “This statement by America’s second-largest doctors group demolishes the myth that the medical community doesn’t support medical marijuana.”

“The ACP’s statement smashes a number of other myths, including the claims that adequate substitutes are available or that marijuana is unsafe for medical use,” Kampia added.