WASHINGTON

ONCE AGAIN the cancer diagnosis of a well-known national figure — in this case Sen. Ted Kennedy — has sparked a flurry of interest in efforts to treat and cure this frustrating, complex and deadly illness. One of the most promising areas of research involves a group of chemicals whose origins may seem shocking.

The chemicals, called cannabinoids, are the active components in marijuana.

Yes, marijuana, the very same drug that seems to generate endless controversy here and abroad, and that our government still claims causes cancer — a claim that appears to stand reality on its head.

The first solid data showing the anti-cancer effects of cannabinoids was developed by U.S. government researchers and published in the Journal of the National Cancer Institute back in 1975. The scientists found that THC, the component that produces marijuana’s “high,” inhibits the growth of lung-cancer cells in the test tube and in mice.

In a world that made sense, this discovery would have set off a frenzy of new research. After all, President Richard Nixon had declared “war on cancer” just a few years before, and vast sums of money were being spent investigating new approaches. But Nixon had also declared “war on drugs,” with marijuana at the top of the demon-drugs list, so our government — by far the world’s largest source of medical research funding — never pursued these remarkable findings. Research ground to a near-complete halt until the late 1990s.

Since then, THC and other marijuana components have been shown to block growth not only of lung tumors but a variety of other cancers, including leukemia, lymphoma and cancers of the breast and skin. These effects seem to occur through a variety of different cellular mechanisms.

As Spanish researcher Dr. Manuel Guzman, one of the world’s leading experts in the field, wrote in a 2003 review in the journal Nature Reviews: Cancer, “Cannabinoids are selective anti-tumor compounds, as they can kill tumor cells without affecting their non-transformed counterparts. It is probable that cannabinoid receptors regulate cell-survival and cell-death pathways differently in tumor and non-tumor cells.”

That is exactly what you want in a cancer drug: Something that kills the malignant cells without harming healthy cells. It’s because most chemotherapy drugs aren’t selective enough that they cause such terrible nausea, vomiting, hair loss and other side effects.

One of the most fruitful areas of research has involved gliomas, the same type of brain tumor that Sen. Kennedy is battling. A search of PubMed, the U.S. government’s medical database, using the search terms cannabis (the scientific name for marijuana), cannabinoid, and glioma turned up 94 scientific-journal articles, most of them published since 2000.

Most are lab or animal studies, demonstrating various mechanisms by which these marijuana chemicals kill glioma cells or stop glioma tumor growth. Amazingly, despite all this evidence, there has been only one, tiny, human study thus far, conducted by Dr. Guzman.

Guzman and colleagues injected THC directly into brain tumors in a handful of patients with recurring, inoperable gliomas — patients considered terminal. It was primarily a safety study, and the THC injections proved completely safe.

Although the researchers concluded that the injection method they used may not have adequately distributed the medicine to all parts of these large tumors, two patients seemed to show definite (albeit temporary) improvement because of the treatment. The researchers urge that additional trials testing THC and other cannabinoids in this and other types of tumors be undertaken.

This is an exciting area of research, but one that has been needlessly — and perhaps lethally — slowed down by the U.S. government’s slavish devotion to anti-marijuana dogma. That most of the work testing these marijuana derivatives as anti-cancer drugs is occurring outside the United States is a sad commentary indeed.

Bruce Mirken, a longtime health journalist, serves as director of communications for the Marijuana Policy Project, www.mpp.org.