In a study by Medical Detection Dogs, the Prostate Cancer Foundation, the Massachusetts Institute of Technology and Johns Hopkins University, three current methods of diagnosing prostate cancer were combined for the first time to detect the disease at an early stage. In larger studies, a tool for diagnosing machine odor development should be developed – a “robot nose” – which could ultimately be a smartphone app of the future with a prototype developed by MIT.
New research from a multinational, interdisciplinary team of scientists from Medical Detection Dogs (MDD) in the UK, Prostate Cancer Foundation (PCF), Massachusetts Institute of Technology (MIT), Johns Hopkins University – and a friendly pair of specially trained cancer-sniffing dogs MDD – have scientifically proven that a dog’s nose is key to detecting prostate cancer: a more accurate, non-invasive, early diagnostic tool that can be used to differentiate between potentially fatal high-Gleason cancers and low-grade cancers that are less dangerous.
Observations from the mid-2000s have shown that dogs can accurately spy out early prostate and other cancers with impressive accuracy, but researchers did not know exactly what olfactory elements the dogs perceived and how they processed the information. In a new article published today in PLOS ONE, the researchers combined three approaches for the first time – detection of odor disorders in dogs, artificial intelligence (AI)-assisted chemical analysis of volatile organic compounds (VOCs) in urine samples, and microbial analysis the same urine samples from men biopsy suspected of having prostate cancer.
A four-year-old Labrador and a seven-year-old Vizsla were trained to detect the smell of prostate cancer in urine samples from patients with the disease, including Gleason 9 prostate cancer – the deadliest tumors that would benefit most from early detection.
The results showed that the dog’s olfactory system was 71 percent sensitive – the rate at which the dogs correctly identified positive samples – and 70-76% specifically – the rate at which the dogs found negative samples, including those with other diseases , in detecting Gleason 9 correctly ignored prostate cancer from blinded samples. The dogs also correctly identified when 73% of the blinded patient samples did not have the disease. This compares favorably to the most widely used prostate cancer test, the PSA blood test, and shows how a new screening tool based on the dog’s nose can aid the PSA test and improve early detection, leading to better health outcomes and save lives.
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This is the first truly controlled study – both human researchers and dogs were double-blind, with samples taken from cancer patients versus otherwise healthy patients. The results show that canines can be trained to recognize the most aggressive and deadly form of prostate cancer from the VOCs. While previous studies using analytical techniques like gas chromatography-mass spectrometry (GC-MS) to identify individual molecules under tightly controlled laboratory conditions have been well done, this new work takes into account the dynamically changing background odor environment of the real world. Identifying the molecules in odor could lead to the development of an artificial dog nose that detects prostate cancer in urine in the same way that biosensing machines, known as machine odor factors, learn from the way trained dogs spy on drugs and explosives also unique molecular odor signatures.
Dr. Claire Guest, Co-Founder and Scientific Director of Medical Detection Dogs and lead author on the study, said, “This study showed that a dog’s nose can be key to a much-needed, more accurate and non-invasive method in the early diagnosis of prostate cancer. Expert-trained cancer detection dogs Florin and Midas used urine samples to quickly and accurately detect extremely aggressive prostate cancers and even discriminated against the urine of patients with other prostate diseases. This additional information could aid the PSA and enable earlier, non-invasive, sensitive detection of clinically aggressive prostate cancers that would benefit most from early diagnosis, simply from a urine sample. This has tremendous potential, and in time the canine nose’s ability could be transferred to an electronic device. “
“One of the main points of this work is that dogs not only recognize prostate cancer, but also the deadliest types of prostate cancers – the ones that would benefit most from early detection. The results could now lead to the future development of a more sensitive and specific prostate cancer diagnosis that goes beyond the current PSA test, ”said Dr. Jonathan W. Simons, President and CEO of PCF and co-author of the study. “With compelling evidence in support of this approach, we are planning larger studies using dog odor, urine VOCs, and urinary microbiota profiling to develop a machine odor diagnosis tool, a ‘robotic nose’, if you will, that ultimately does May have the form of a smartphone app of the future. “
“Imagine a day when smartphones can send a warning that there is a potential risk of highly aggressive prostate cancer, years before a doctor notices a surge in PSA levels. The incredible work these dogs do is critical as we advance this program to develop an improved method for the early detection of prostate cancer. Equally important is that men can be citizen scientists and contribute to the biobank that is helping us solve this much-needed problem. Once we have the prostate cancer machine nose built, it can be fully scaled to other diseases, ”added Dr. Andreas Mershin, physicist and scientist at the Center for Bits and Atoms of the Massachusetts Institute of Technology and co-author of the study added.