Refers to article:
Olfactory Detection of Prostate Cancer by Dogs Sniffing Urine: A Step Forward in Early Diagnosis
Accepted 6 October 2010
February 2011 (Vol. 59, Issue 2, pages 197 - 201)
I read with interest the article by Cornu et al, who demonstrated that dogs can be trained to detect prostate cancer (PCa) with 91% sensitivity and specificity by smelling urine , thus surpassing the diagnostic performance of most PCa biomarkers currently available. These results are appealing, but they merit further discussion.
A foremost aspect is the identification of volatile organic compounds (VOCs) that appropriately trained dogs might be able to detect. Although Cornu et al reported that metabolomics studies have identified only sarcosine as a candidate biomarker for PCa , the systems biology approach has revealed a variety of novel proteins as well as molecular networks with altered expression in this type of cancer. Ummanni et al, for example, used highly sensitive two-dimensional differential gel electrophoresis coupled with mass spectrometry to discern proteins differentially expressed in cancer compared to benign prostate tissue . The resulting protein profile revealed higher amounts of dimethylarginine dimethylaminohydrolase 1, arginase type 2, eukaryotic initiation factor 4A-III, pyrophosphatase (inorganic) 2, protease-activated receptor 4, peroxiredoxin (Prdx) 3, and Prdx 4 in cancer tissue as compared with the normal counterpart.
In a comprehensive review of the current scientific literature, Steuber et al highlighted that putative biomarkers for PCa include human kallikrein-related peptidase 2, urokinase-type plasminogen activator receptor forms, and early prostate cancer antigen . More recently, Duijvesz et al provided a comprehensive overview of prostasomes, concluding that these particles might be a valuable source of novel and reliable biomarkers such as annexins, Rab proteins, and heat shock protein 70 and 90 . Thus whatever VOCs the dogs might be able to identify in the urine of PCa patients, it is conceivable that this would fall within those previously mentioned.
An additional issue to be considered is the recent development of the so-called Prostate Health Index (“phi”), which was recently proven to be the most accurate predictors of PCa (area under the curve: 0.756) . Before drawing any conclusion about the diagnostic performance of dogs, it is essential to test their smelling ability against this novel and reliable index.
Conflicts of interest
The author has nothing to disclose.
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U.O. di Diagnostica Ematochimica, Dipartimento di Patologia e Medicina di Laboratorio, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
© 2011 European Association of Urology, Published by Elsevier B.V.