Simply passing a handheld device over the body of a suspected cancer patient could reveal a tumour, inventors have claimed.
Most cancer scanners are bulky and expensive
The device, which looks a little like the metal detectors used in airports, works because different types of body tissue resonated in different ways when exposed to a fluctuating frequency of microwaves given off by the device.
This resonance can be detected because it interferes with the signal.
Tumour tissue resonates at different frequencies to healthy tissue - so the presence of a cancer can be identified quickly.
Normally, a patient would have to undergo a CT or MRI scan to allow doctors to spot cancer growing inside them.
Obviously, the device, developed at the University of Bologna in Italy, cannot give doctors the precise location and size of tumours - an important factor in determining treatment.
In clinical trials at a hospital in Milan, the scanner was able to correctly identify 93% of prostate cancer patients whose condition was later confirmed by a biopsy operation.
Dr Carlo Bellorofonte, who led the study, told New Scientist magazine: "The results are amazing.
"The scanner seems ideal for mass-screening of cancer because it is rapid, non-invasive and highly sensitive."
A separate study of breast cancer patients showed a lower success rate - 66% of cases were detected by the device.
The results have yet to be accepted for publication in a major medical journal - and the device will not find favour in hospitals elsewhere until they are.
The detector was originally developed as a potential way to detect landmines.
The company behind it hopes to market the device, perhaps for £20,000 a time, later this year.