Breath Analysis May Detect Cancer

Following a recent study revealing that dogs can distinguish breast and lung cancer in people vs healthy controls, researchers concluded that breath analysis has the potential to reduce the uncertainty in cancer diagnosis.

In the study, published in the March 2006 issue of Integrative Cancer Therapies, researchers reveal the evidence that a dog's extraordinary scenting ability can distinguish people with both early- and late-stage lung and breast cancer from healthy people.

Five household dogs in the study were trained within a three-week period to detect lung or breast cancer by sniffing the breath of cancer patients. The trial was comprised of 86 cancer patients (55 with lung cancer and 31 with breast cancer) and a control sample of 83 healthy patients. All cancer patients had been recently diagnosed through biopsy-confirmed conventional methods. During the study, the dogs were presented with breath samples from the cancer patients and controls, captured in a special tube. The dogs were trained to give a positive identification of a cancer patient by sitting or lying down directly in front of a test station containing a cancer patient sample, while ignoring control samples. Standard methods were used to train the dogs.

The results showed that the dogs could detect breast and lung cancer with sensitivity and specificity of 88% and 97%, respectively. The accuracy rate persisted even after adjusting for the fact that some lung cancer patients were currently smokers. In addition, the study confirmed that the trained dogs could even detect the early stages of both lung cancer and breast cancer.

The study was led by Michael McCulloch of the Pine Street Foundation in San Anselmo (CA, USA) and Tadeuz Jezierski of the Polish Academy of Sciences, Institute of Genetics, and Animal Breeding (Wolka Kosowska, Poland). A case of a dog alerting its owner to the presence of a melanoma by constantly sniffing the skin lesion brought the capability to light. The current study is the first to test whether dogs can actually detect cancers only by sniffing the exhaled breath of cancer patients.

The researchers concluded that further work should be conducted to standardize and expand the methodology of analyzing the breath of cancer patients.