Experts studying breath samples said dogs were able to accurately sniff out lung cancer cases seven out of 10 times.
It didn't matter if the patients who gave the sample had recently smoked.
The findings have many hoping that an earlier detection system, based on supersensitive canine noses, won't be far off.
"If we were able to take what they're doing and translate it into a test, there is a possibility, and let me emphasize a possibility, that we could take this and use it as a screening test," said Dr. Len Lichtenfeld of the American Cancer Society.
Dogs already are widely used to sniff out things like drugs and explosives.