The cells of a skin cancer tumor give off a smell that is quantitatively different from that released from normal skin, according to a new study. This discovery is likely to lead to a new non-invasive method of testing for the disease, which affects over one million new patients per year.

The research, presented at the 236th annual conference of the American Chemical Society, was based on a previous study that found that normal skin emits a specific set of Volatile Organic Compounds (VOCs), whose relative concentrations vary with age. It has also been known for some time that skin cancer releases a specific, perceptible odor, since some dogs are able to distinguish skin cancer tumors from normal skin – but until now no one has been able to quantify the differences.

In the current study, the researchers used chromatography (which uses a broad range of techniques to separate and analyze complex mixtures) to sample the air above the sites of skin tumors in 11 patients who had been diagnosed with basal cell carcinoma and compared it to the skin of 11 healthy patients. They found that while the same chemicals (VOCs) were present in both groups, the concentrations of some compounds were consistently higher or lower in skin cancer patients. Since the VOCs varied in predictable ways between cancerous and healthy skin, the researchers were able to determine an “odor profile” for basal cell carcinoma.

Next the researchers are hoping to determine “odor profiles” for the other two types of skin cancer, squamous cell carcinoma and the most dangerous form, melanoma. Once this is completed, it should be possible to develop a mechanical sensor to scan patients for skin cancer.

Head researcher, Michelle Gallagher, envisions an electric “E-nose” sensor that can be waved across the skin and make a sound if cancer is detected. At present, the only way of diagnosing the disease is to visually scan the skin and take a biopsy, which can be painful or even miss a tumor altogether if it is not clearly visible.

The study was carried out at the Monell Chemical Senses Center in Philadelphia, Pennsylvania.