Scientists have developed a tiny camera that fits inside a pill, with the goal of allowing patients who swallow it to be assessed for warning signs of esophageal cancer.

The camera is designed to take high-quality, colour pictures in confined spaces. Researchers with the University of Washington say the device is essentially a small endoscope that is more comfortable for the patient and cheaper to use than current technology.

Its first use on a human — scanning for early signs of esophageal cancer — will be reported in an upcoming issue of IEEE Transactions on Biomedical Engineering.

"Our technology is completely different from what's available now. This could be the foundation for the future of endoscopy," lead author Eric Seibel, a University of Washington professor of mechanical engineering, said in a news release.

The Canadian Cancer Society estimates 1,550 new cases of cancer of the esophagus were diagnosed in this country in 2007, the vast majority among men. The esophagus is a long, muscular tube that leads from the back of the mouth to the stomach.

Esophageal cancer often follows a condition called Barrett's esophagus, marked by a change in the tube's lining. Patients with Barrett's esophagus can be healed, avoiding the deadly cancer. But because internal scans are expensive, most people don't find out they have the condition until it has progressed to cancer, and by that stage the survival rate is less than 15 per cent.

"These are needless deaths," Seibel said. "Any screen that detected whether you had a treatable condition before it had turned into cancer would save lives."

Most of today's endoscopes capture images using a long, flexible cord about nine millimetres wide — about the width of a human fingernail. Because the cord is so wide, patients must be sedated during the scan.

The endoscope developed at the University of Washington is encased in a pill tethered to a 1.4 mm wide cord, and is so small it doesn't require the patient to be sedated. 

Seibel acted as the human volunteer in the first test of the device. He says it felt like swallowing a regular pill and the tether did not bother him.

According to University of Washington officials, a wireless scope manufactured by a different group is now being marketed for esophageal cancer screening. The competing technology comes in a pill about the width of an adult fingernail and twice as long.

By contrast, the university says its endoscope is about half as big and it fits inside a standard pill capsule.

Seibel says the disadvantage of the competing wireless capsule is it only allows a single "flyby view."

"You have no control over the other pill once it's swallowed. It just flutters down," Seibel said. But since his scope is tethered, doctors should be able to move it up and down along a region of interest.

"The next big challenge is to make this cheaply," Seibel said. The researchers are negotiating a contract to commercialize the technology.