A combination of industry secrecy, lack of money and shortage of time is keeping the results of many clinical cancer trials locked away and depriving doctors of crucial information, campaigners said on Monday.

Officials from Cancer Research UK said that while strongly positive and strongly negative trial results did see the light of day very quickly, they were the minority and that middle-of-the-road results often remained a secret.

“One quarter of large scale clinical trials are never published,” Richard Sullivan, head of clinical programmes at the cancer pressure group, told the annual meeting of the British Association for the Advancement of Science.

“It is disturbing to think that important information on these trials is being left to gather dust,” he added.

Professor Fran Balkwill, also from Cancer research UK, said one of the reasons was industry secrecy but another was that people were also reluctant to use time or space to publish marginal or negative data.

But this information - which might not in itself be conclusive - could feed into other research and help save time and money. “It is important that everything we know is published,” she said.

Sullivan said that because of the lack of regulation in the industry, one-third of clinical trials were never even registered let alone published.

He called for all clinical trials to be registered centrally and for all results to have been published within five years of completion.

Not only would this ensure that knowledge was available to all, it would also save time and large amounts of money by avoiding unnecessary duplication, which in Britain alone amounted to hundreds of thousands of pounds.

He said companies had a responsibility to society to issue their trial results to avoid waste and ensure that standard practice was not unduly influenced by outcomes that favoured only the positive.

“If only positive results are published this can distort medical literature and leave doctors thinking a treatment is more effective that it actually is,” he said. “There is an obligation to publish everything.”