Not long ago, I asked a respected cancer researcher if he could send me raw data from a trial he had recently published. He refused. Sharing data would make the study team members “uncomfortable,” he said, as I might use this to “cast doubt” on their results.

I’d heard this before: as a statistician who designs and analyzes cancer studies, I regularly ask other researchers to provide additional information or raw data. Sometimes I want to use the data to test out a new idea or method of statistical analysis. And knowing exactly what happened in past studies can help me design better research for the future. Occasionally, however, there are statistical analyses I could run that might make an immediate and important impact on the lives of cancer patients.

A few years back, a study was published showing that a certain drug could prevent one type of cancer. The problem was that the drug didn’t work very well and had some side effects, so almost no one used it. At the same time, a colleague showed that a protein found in the blood could predict which patients were at high risk for cancer. We put two and two together and realized that we could use the protein test to work out which patients would benefit from the drug.

To make things even easier for us, it turned out that the researchers who had conducted the trial had actually measured this protein in all their patients. So we wrote to them and asked whether they would share their data. They refused on the grounds that they might consider a similar analysis at some point in the future. But years have passed, no such analyses have been forthcoming and few patients are benefiting from what could be a very effective drug.

Given the enormous physical, emotional and financial toll of cancer, one might expect researchers to promote the free and open exchange of information. The patients who volunteer for cancer trials often suffer through painful procedures and harsh experimental treatments in the hope of hastening a cure. The data they provide ought to belong to all of us. Yet cancer researchers typically treat it as their personal property.

I’m sometimes told that sharing data would violate patient privacy — though changing names to codes is easy enough. Other requests are killed by red tape. When a colleague and I wanted to analyze the data from a completed breast cancer trial, merely getting permission to speak to the study’s organizing committee required a one-hour phone call with the scientist in charge of the agenda. Only after another one-hour call with the committee itself were we allowed to submit a formal proposal — to which we received no response.

Most refusals are more blunt. “I am not prepared to release the data at this point,” one researcher wrote me, even though he was a government employee and his trial, which had been published several years earlier, was federally financed.

Dr John Kirwan, a rheumatologist from the University of Bristol in England, has studied researchers’ attitudes on sharing data from clinical trials. He found that three-quarters of researchers he surveyed, as well as a major industry group, opposed making original trial data available. It is worth restating this finding: most scientists doing research on how best to help those in pain, or at risk of death, want to keep their data a secret.

Dr. Kirwan went on to ask his subjects why. Their reasons were entirely trivial: one cited the difficult of putting together a data set (wouldn’t this have to be done anyway in order to publish a paper?); another was concerned that the data might be analyzed using invalid methods (surely a judgment for the scientific community as a whole). This is something of a clue that the real issue here has more to do with status and career than with any loftier considerations. Scientists don’t want to be scooped by their own data, or have someone else challenge their conclusions with a new analysis.

Yet this is exactly what cancer patients need. They want new results to be published as quickly as possible and to encourage a robust debate on the merits of key research findings.

An acquaintance of mine was recently diagnosed with breast cancer, and it gives me some comfort to know that there are drugs she can take that will improve her chance of cure. We know that these drugs are of benefit because more than 20 years ago, a group of Oxford statisticians persuaded researchers around the world to pool data from their breast-cancer trials.

With the rise of the Internet, sharing data has become a simple matter. Geneticists, for example, publish their raw data on a central Web site. The data from medical trials are given freely by patients. They should insist that these belong to science as a whole.