Drug Puzzle: When Do Risks Outweigh Benefits?

In one of the great examples of the mixed messages of science, the same study that killed the blockbuster arthritis drug Vioxx after showing that it had heart risks also found that the drug had a significant benefit: It prevented precancerous colon polyps in some patients, one of the study's principal researchers said.

But the drug's maker, Merck, and the researcher, Dr. Robert Bresalier, said that neither Merck nor the researchers had known that Vioxx prevented polyps when Merck stopped the study and withdrew the drug from the market.

"At the time we made our decision to voluntarily withdraw Vioxx, the study had not yet been completed, and efficacy results had not been disclosed to Merck by the study's steering committee," Christopher Loder, a Merck spokesman, said.

Instead, because an independent board overseeing the study had reported that Vioxx, whose generic name is rofecoxib, was associated with a twofold increase in heart attacks and strokes, an unacceptable risk for otherwise healthy people, Merck announced on Sept. 30 that it was halting the 2,000-patient study. It withdrew Vioxx from the market and stopped all other studies that asked if the drug could prevent cancer.

The company says it has no plans to bring the drug back.

Bresalier, a professor and chairman of the department of gastrointestinal medicine and nutrition at M.D. Anderson Cancer Center in Houston, explained the polyp results had emerged in data analyses only a few weeks ago, showing the study was "substantially positive." He has not yet presented the results to other scientists for review. The study was paid for by Merck.