NEW YORK Just three weeks after America's most prestigious medical journal declared an expensive new cancer drug to be "revolutionary" and "maybe even a cure" for early breast cancer, the most prominent British medical journal came to the opposite conclusion Wednesday.

"The available evidence is insufficient to make reliable judgments," editors of The Lancet wrote in an editorial published online Wednesday. "It is profoundly misleading to suggest, even rhetorically, that the published data may be indicative of a cure for breast cancer."

In a telephone interview, The Lancet's chief editor, Dr. Richard Horton, said he was "quite angry" that Herceptin has been portrayed as such a wonder drug in The Lancet's U.S. counterpart, the New England Journal of Medicine.

"Study results are preliminary, inconsistent and raise extremely serious concerns about safety," he said.

Herceptin is designed to treat women with breast tumors that bear a common genetic mutation associated with aggressive disease that responds poorly to conventional treatments.

The buzz surrounding Herceptin has led patient groups worldwide to demand the drug from governments and insurers, even though it is not licensed for early-stage breast cancer. It is approved only for use in advanced cancers.

The buzz intensified last month, when the New England Journal of Medicine published two preliminary studies concluding that the drug seemed to be extremely effective, accompanied by a glowing editorial.

The Lancet decided to publish its editorial early and online Wednesday, Horton said, after the British health secretary, Patricia Hewitt, publicly demanded the National Health Service to provide the drug to a patient who had sued to be given the medicine. In France, pressure to release Herceptin was so intense that regulators bypassed normal channels earlier this year to make it more widely available to breast cancer patients.

At cost of about 35,000, or about $41,200, for a full treatment course, governments have been hard pressed to pay for Herceptin. But Horton said the current debate was simply about whether the drug worked and was safe.

"The last thing we should want is to have a politician campaigning on behalf of a drug," Horton said. "It's a crazy way to make what should be a scientific decision."

Katja Prowald, a spokeswoman for Roche, the Swiss company that markets Herceptin in Europe, said scientists at the company had "read the editorial and said that the statements it contained were not correct."

The company will release a further analysis by Thursday, she said, noting that Roche was currently busy answering questions about Tamiflu, a Roche drug that many countries are stockpiling against bird flu.

The dispute surrounding Herceptin began earlier this year when researchers, at a meeting of the American Cancer Society, presented promising early data on the use of Herceptin to treat early breast cancer. Two articles, containing further interim data, were published in the New England Journal of Medicine on Oct. 20.

The studies were funded in part by Genentech, the company that developed the drug, and by Roche.

According to the studies, women who received Herceptin along with standard chemotherapy had half the rate of recurrence after one year than those who did not receive the drug. Researchers from a consortium of prestigious international medical centers considered the results compelling enough that women who had been in the study's control group, who initially received no Herceptin, were belatedly offered the medicine.

But some scientists have long had misgivings about the data, or at least the drug's golden image. Last week in the Journal of the American Medical Association, Dr. Victor Montori of McMaster University in Toronto pointed out that when trials are stopped early, the preliminary analyses can show "implausibly large treatment effects," and he urged "skepticism" in viewing the data.

Horton pointed out that one of the New England Journal of Medicine articles combines data from two patient trials that may not be comparable. Also, he noted that a small but significant number of women receiving Herceptin develop severe heart failure, and that problem has not yet been adequately studied.

He said the hoopla surrounding Herceptin resulted from a synergy between desperate patients desiring better treatments and drug companies looking for profit, creating what he called an "unholy alliance."

He urged that regulatory review boards be given the time necessary to thoroughly evaluate the drug, saying: "We need to have a strong spine to make sure that scientific evaluation remains scientific and is not dominated by politics."

The Lancet said: "The debate about the availability of Herceptin to women with early breast cancer demands cooler heads than have so far prevailed, in politics, in public, and even in medical journals."