An "intelligent" surgical knife can tell surgeons, within seconds, whether the tissue they are removing is cancerous or not, British researchers reported Wednesday.

In the first study to test the invention in the operating theater, the "iKnife" diagnosed tissue samples from 91 patients with 100 percent accuracy, instantly providing information that normally takes up to half an hour to reveal using laboratory tests, researchers at Imperial College London reported in the US journal Science Translational Medicine.

In cancers involving solid tumors, removal of the cancer in surgery is generally the best hope for treatment. The surgeon normally takes out the tumor with a margin of healthy tissue. However, it is often impossible to tell by sight which tissue is cancerous. One in five breast cancer patients who have surgery require a second operation to fully remove the cancer, the researchers said.

In this study, the researchers created the "iKnife" based on electrosurgery, a technology invented in the 1920s that is commonly used today. Electrosurgical knives use an electrical current to rapidly heat tissue as they cut, creating smoke that is normally sucked away by extraction systems.

The inventor of the iKnife, Zoltan Takats of Imperial College London, said he realized that this smoke would be a rich source of biological information.

To create the iKnife, he connected an electrosurgical knife to a mass spectrometer, an analytical instrument used to identify what chemicals are present in a sample.

Different types of cell produce thousands of metabolites in different concentrations, so the profile of chemicals in a biological sample can reveal information about the state of that tissue, he said.

The researchers first used the iKnife to analyze tissue samples collected from 302 surgery patients, recording the characteristics of thousands of cancerous and non-cancerous tissues, including brain, lung, breast, stomach, colon and liver tumors to create a reference library. The iKnife works by matching its readings during surgery to the reference library to determine what type of tissue is being cut, giving a result in less than three seconds.

The technology was then transferred to the operating theater to perform real-time analysis during surgery. In all 91 tests, the tissue type identified by the iKnife matched the post-operative diagnosis based on traditional methods.

Takats said these results provide "compelling evidence" that the iKnife can be applied in a wide range of cancer surgery procedures.

"It provides a result almost instantly, allowing surgeons to carry out procedures with a level of accuracy that hasn't been possible before, " he said in a statement. "We believe it has the potential to reduce tumor recurrence rates and enable more patients to survive."