Skin cancers may one day literally be "sniffed out" say researchers who used a chemical analyser on basal cell tumours, the most common form of the disease.
They found that air tested above the tumours had a different "smell" to that from the same patches of skin in healthy volunteers.
Study leader Dr Michelle Gallagher, from the Monell Chemical Senses Center in Philadelphia, said: "Our findings may allow doctors to screen for and diagnose skin cancers at very early stages."
The scientists hope to characterise skin odour profiles associated with other forms of skin cancer, including the most serious type, melanoma.
Previous research by the same team identified almost 100 different chemical compounds given off by the skin and found in the air above the forearm and upper back.
But Nina Goad, from the British Association of Dermatologists, said: "While this research is interesting, it is still quite theoretical at present.
"These cancers do not normally pose much of a problem for diagnosis when seen by a specialist. For that reason, this research is unlikely to impact greatly on how basal cell carcinomas are presently diagnosed."