Research center investigates smell of skin cancer

Previous studies have shown that lung and breast cancer can be detected in the breath of cancer patients, but new research proves that skin cancer also has a scent.

In 2006, a group of researchers trained dogs to detect gas compounds in the exhaled breath of humans that indicated the presence of lung and breast cancer. The dogs proved overwhelmingly correct in identifying vials containing breath samples from the cancer patients compared with samples from healthy people.

In July, a group of scientists at the Monell Chemical Senses Center in Philadelphia published a study in the British Journal of Dermatology on the various volatile organic compounds (VOCs) that are present in healthy human skin, specifically on the forearm and back. The team used gas chromatography and mass spectrometry to analyze the “odor profiles” of the skin of 25 people of different ages and sexes.

Odorous VOCs are known to come from the axillae (underarms), but VOCs from other skin surfaces are also present and measurable. In fact, after compensating for external factors (such as VOCs from the air in the room and from soap or cosmetic products), the team found nearly 100 compounds present on the skin of the subjects. The scientists found that forearms and back had different VOC make-ups, and the concentration of the chemicals varied depending on the age of the subject.

In follow-up research presented at an American Chemical Society meeting in August, the Monell team measured the type and concentration of VOCs that are present in healthy skin versus skin with basal cell carcinoma, the most common type of skin cancer. The team compared the skin odor profiles of 11 subjects with basal cell carcinoma and 11 healthy subjects.

Analytical organic chemist George Preti, PhD, principal investigator for the Monell studies, said that skin with basal cell carcinoma tumors emitted the same types of VOCs as healthy skin, but in different concentrations.

“It’s a quantitative difference we’re looking at, not a qualitative one,” Preti said.

He said that the goal is to be able to create a device that can pick up the VOCs from the skin and be able to detect signs of cancer early on so it is more treatable.

“Ultimately what you want to do is be able to identify a group of biomarkers amenable to being detected with a hand-held sensor,” Preti said. “You’d have to have a ‘smart’ sensor; you would train it to look for certain types of compounds.”

This type of Star-Trek like sensor technology is still years in the future. The devices would possibly use carbon nanotube-based sensors, but the science behind it is still in the basic research area, Preti said, and is probably at least five-10 years away.

The new research is ongoing and will likely be published in a journal before the end of the year. Before the study is finished, Preti and his team will also look at squamous cell carcinoma and melanoma – the deadliest type of skin cancer – and develop odor profiles for all three skin cancer types.

“We have not had any of the other tumors sampled directly,” he said. “We’re planning on it but we don’t have any subjects as yet sampled.”

Preti said his team does not plan on testing whether dogs can detect the odor of cancer, as was studied in the 2006 report, “Diagnostic Accuracy of Canine Scent Detection in Early- and Late-Stage Lung and Breast Cancers,” published in Integrative Cancer Therapies.

In that study, researchers found that dogs could differentiate the exhaled breath of humans with lung and breast cancer from that of healthy humans.

“There have been several studies done on looking for biomarkers,” Preti said. “It seems that everyone finds something different. … We don’t know if the dogs are smelling the same things that we are seeing with our instrumentation.”

However, he did say that part of the new study would involve testing whether people notice a difference in smell.

“We’re going to see if we can detect an olfactory difference,” he said.

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