The active chemical in marijuana has been proven highly effective in relieving the nausea and discomfort of cancer chemotherapy, and should be offered to thousands of patients as soon as possible, according to a leading medical journal.

Several new studies and an editorial in the Annals of Internal Medicine all conclude that the effectiveness of tetrahyudrocannubinol (THC) is no longer in doubt, and the editorial says its use could save lives by helping patients continue use of the sometimes unpleasant anticancer drugs. The Annals is the monthly journal of the American College of Physicians; the main organization of the country's specialists in internal medicine.

Some patients now buy and take illegal marijuana, and an even smaller number get it legally from their doctors on an experimental basis. But its wide use is still blocked by federal red tape and by a lack of interest in the drug industry in marketing a nonpatentable, controversial drug, says the editorial's author, Dr. John Laszlo of Duke University.

In May a federal interagency committee headed by Dr. Seymour Perry of the National Institutes of Health told the White House that more studies were needed to prove THC's or marijuana's effectiveness.

Yesterday Perry said "a number of studies" are indicating that THC can help some patients, and the committee will take another look at the matter next month.

Meanwhile, complains, Laszlo, both "reputable scientists and suffering patients believe the government is not helping them."

Marijuana has been studied for some years as a possible antinausea drug for chemotherapy patients. But until now results had been confusing and there had been no studies large-enough or well-controlled enough, says Laszlo, to provide any scientific proof of its effectiveness.

That proof has been provided, he said in an interview, by two reports summarized in the same medical journal and a number of other reports about to appear in other journals pointing in the same direction.

The general conclusion is that given in proper doses and, sometimes, several hours before chemotherapy, THC has proved more effective in most studies than prochlorperazine (Compazine), the main antinausea drug used today.

This is especially true in younger patients, who may have had some experience with marijuana, he said, but it is not always true for older patients who object to any intoxicant or disorientation.

In a third study reported in the Annals, one at the Mayo Clinic, older patients found THC no more effective than prochlorperazine, and often complained of unpleasant side effects.

Duke doctors, on the other hand, gave THC to 41 cancer patients who were not helped at all by other drugs, with "surprisingly good results in more than two-thirds."

"To summarize," Laszlo said, "we can safely conclude that [THC can] clearly have a salutory effect on drug-induced nausea and vomiting."

A Food and Drug Administration offical, Dr. Edward Tocus, said yesterday that "it finally looks as though a number of well-done studies show" THC is "significantly more effective" than other drugs.

But the only doctors who can get any THC for their patients, Laszlo said, are a small number of "the most persistent investigators who will write research protocols and persevere" ingetting special licenses from federal and state drug enforcement agencies.

He urged the Justice Department's Drug Enforcement Agency to reclasify marijuana as a medically useful, rather than unproved, drug. Then, he said, FDA and the National Cancer Institute could at least provide it to registered doctors as a short-term solution."

That would still get it to a limited number of specialists who help NCI test drugs. Tocus said. What FDA needs, he said, is for some drug firm "to come forward and propose developing and marketing THC."

One problem, Laszlo said, is that several federal agencies and divisions -- FDA, DEA, NCI and several others -- have "pieces of the action" and it can "take forever to get them all to agree."