Researchers from Schillerhoehe Hospital in Germany have found that sniffer dogs can reliably detect lung cancer in its early stage. Lung cancer is not strongly associated with any symptoms and early detection is often by chance. Current methods of detection are unreliable and scientists have been working on using exhaled breath specimens from patients for future screening tests. This new study aimed to assess whether sniffer dogs could be used to identify volatile organic compounds (VOCs) that are linked to the presence of cancer in the breath of patients. The researchers worked with 220 volunteers, including lung cancer patients, chronic obstructive pulmonary disease (COPD) patients and healthy volunteers. They used dogs that had been specifically trained. The dogs successfully identified 71 samples with lung cancer out of a possible 100. They also correctly detected 372 samples that did not have lung cancer out of a possible 400. The dogs could also detect lung cancer independently from COPD and tobacco smoke. These results confirm the presence of a stable marker for lung cancer that is independent of COPD and also detectable in the presence of tobacco smoke, food odours and drugs. "In the breath of patients with lung cancer, there are likely to be different chemicals to normal breath samples and the dogs' keen sense of smell can detect this difference at an early stage of the disease," Thorsten Walles from Schillerhoehe Hospital, and author of the study, said. The study was published in the European Respiratory journal.