Ever heard the one about the dog that could sniff out cancers? Well, the story could have a basis in fact. Scientists revealed yesterday how odours from the skin could be used to detect certain tumours.

Human skin emits hundreds of chemicals known as volatile organic compounds, many of which are odorous. By comparing the chemicals released by the skin of healthy volunteers to those with basal cell carcinoma, the most common form of skin cancer, scientists were able to characterise the "smell" of the tumours.

Michelle Gallagher, a chemist at Monell Chemical Senses Centre in Philadelphia, took the inspiration for her experiments from stories that dogs could sniff out cancers. "Researchers have speculated that tumours give off different odours, but we're the first to identify and quantify the compounds involved," she said.

"This research opens 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."

Gallagher analysed the air above tumours in 11 patients with basal cell carcinoma, the most common skin cancer. These were compared with the odour from the skin of 11 people without cancer.

The findings were presented yesterday at the annual meeting of the American Chemical Society in Philadelphia.

The scientists have applied for a patent on their work. They eventually plan to identify odour profiles for all types of skin cancer, including squamous cell cancer and melanoma. If all goes well, the technique could be combined with an electronic nose that could aid in the diagnosis of cancers.

Lara Bennett, a science information officer at Cancer Research UK, warned against expecting too much from the research and said larger studies were required: "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," she said.

Nina Goad of the British Association of Dermatologists also welcomed the research but said that, at present, skin cancers tend not to 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."