WASHINGTON - One of the biggest worries for patients undergoing cancer surgery is whether surgeons will miss some of the diseased tissue.

That worry could be over with a new pencil-sized tool developed by scientists and engineers at the University of Texas at Austin, according to a study published on Wednesday.

The tool, dubbed the Mas-Spec Pen, allows surgeons removing a tumor to detect cancerous cells in tissues in seconds, allowing them to know immediately if they have found and removed all of the cancer.

Currently it can take days to determine if the surgeons got everything. What they miss could lead to a return of the cancer or, at least, another operation to further clean up the affected tissues.

The study said the pen can identify cancerous tissue in about 10 seconds.

The MasSpec Pen is touched to the tissue during surgery, drawing up small molecules to be analyzed by a miniaturized mass spectrometer built inside the stylus. It can identify the cancerous cells through distinct molecules called metabolites.

That allows surgeons to keep cleaning out cancerous cells until they are near-certain to have cleared everything. The surgeons can also better decide which tissue to leave in the patient's body.

Tests on tissues removed from 253 cancer patients showed the new tool was "more than 96 percent accurate", according to the study.

"Any time we can offer the patient a more precise surgery, a quicker surgery or a safer surgery, that's something we want to do," said James Suliburk, head of endocrine surgery at Baylor College of Medicine and a collaborator on the project.

"This technology does all three. It allows us to be much more precise in what tissue we remove and what we leave behind," he said.

Agence France-presse