Previous studies have suggested that cancerous tumours could have different odours, and there have been claims that dogs can sniff out the disease.
Now chemists have discovered what they call the scent of basal cell carcinoma – the most common form of skin cancer. They hope it will lead to quicker ways of diagnosing the disease, using a hand-held scanner or sensor waved over the skin.
But experts said much more work was needed before a reliable test based on cancerous odours could be used.
The latest research, published in the British Journal of Dermatology and presented at the American Chemical Society meeting in Philadelphia, studied tumours in 11 patients with skin cancer.
Using advanced chemical analysis techniques, scientists took samples of air from above these patients' tumour areas and compared them with samples from above the skin of volunteers without cancer.
The researchers, from the Monell Chemical Senses Centre in Philadelphia, found varying levels of chemicals around the skin of the cancer patients, compared with the other volunteers.
Dr Michelle Gallagher, the lead researcher, said: "We found a different profile of chemicals above tumour sites relative to healthy skin.
"The same chemicals are present, but at skin cancer sites some chemicals are increased, while others are decreased compared to healthy individuals."
The researchers eventually hope to identify a reliable "odour profile" for all three forms of skin cancer, including melanoma – the most deadly form of the disease.
It is hoped that method can then be combined with the development of "electronic nose" technology, designed to identify odorous chemicals.
Dr Gallagher said: "Researchers have speculated that tumours give off different odours, but we're the first to identify and quantify the compounds involved in skin cancer odours.
"This research opens the doors to potential new approaches to skin cancer diagnosis, based on the profile of skin odours, hopefully leading to more rapid and non-invasive detection and diagnosis."
About 2,300 people die from skin cancer each year in the UK – the majority from the melanoma form of the disease.
However, the new research received a mixed response from experts.
Dr Lara Bennett, the science information officer at Cancer Research UK, said: "The idea that we could one day detect skin cancer by measuring the scented chemicals released from our skin is extremely interesting, but it's far from clear whether this could work in practice. Our skin releases many different chemicals, and their levels depend on many factors, including the area of the body and the age of the person – factors that would make developing a national skin cancer screen based on detecting them extremely difficult."
Dr Bennett said much larger studies were needed to find out whether a skin cancer test could be developed.
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. They have a distinctive appearance and, if there is any doubt, then biopsy is a simple confirmatory investigation."