Your dog may know you have lung cancer before your doctor does, according to a new study from German researchers.

While man's best friend has been known to reliably sniff out certain forms of cancer, the study, published in the European Respiratory Journal, found that dogs can sniff out lung cancer in a patients' breath even when that person had recently eaten or smoked a cigarette. Moreover, canines were better at detecting the early stages of lung cancer than the latest medical technologies in physicians' disposal.

Lung cancer is the leading cause of cancer deaths in the United States, according to the Mayo Clinic, which reports the disease claims more lives each year than colon, prostate, ovarian, lymph and breast cancers combined.

To discover the diagnostic power of a pooch's nose, researchers at Schillerhoehe Hospital in Germany had four specially-trained dogs - including two German shepherds, one Australian shepherd and one Labrador retriever - smell test tubes containing the breath samples of 220 subjects, some whom were afflicted with lung cancer and some of whom were cancer-free. The study authors report the dogs successfully identified 71 of the 100 patients who had the disease. In addition, the animals also correctly identified 372 non-cancerous samples out of 400.

The dogs were also able to detect the difference between lung cancer and chronic obstructive pulmonary disease, which study author Enole Boedeker said is common in patients with lung cancer.

The dogs could recognize the cancer sample as easily as between the breath samples of the healthy study participants, Boedeker said, adding that current lab tests for lung cancer are unable to detect the difference.

The results indicate there are specific volatile organic compounds (VOC) associated with the disease, which are emitted from the surface of cells as they undergo tumor-induced gene and protein changes. Researchers hypothesize that identifying VOCs that certain cells make can help diagnose the ailment even if it is in such an early stage that it is not detectable in a scan.

Some scientists have attempted to imitate dogs' olfactory abilities. In August, Israeli researchers published a study saying that gold nanoparticle sensors - known as an e-nose - to detect VOCs that can distinguish between the breath of healthy patients and those with lung cancer.

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