The diagnosis of prostate cancer has been controversial. Use of the PSA test results in many false positives and some false negatives. Biopsy can cause complications and is also not as accurate as researchers would hope.
Specially trained medical detection dogs in the UK can identify men with prostate cancer at least 90 percent of the time. They are four times more accurate than a PSA test. The dogs can distinguish between urine samples of healthy men and those of men with prostate cancer before men begin to experience symptoms. Medical detection dogs can also detect cancers of the kidney, bladder and breast.
If you would like to read an excellent book on the capabilities and limitations of dogs using their noses for detection, we recommend What the Dog Knows, by Cat Warren. It is on the long list for the PEN E.O. Wilson Award for science writing.