Study Type – Diagnosis (exploratory cohort)
Level of Evidence 2b
What's known on the subject? and What does the study add?
The use of biomarkers to detect a cancer early, especially prostate cancer, is not a new idea and PSA has been proved to be the best biomarker for the early diagnosis of prostate cancer. Since the introduction and wide use of PSA various efforts have been made to find novel biomarkers in both serum and urine of individuals at high risk for prostate cancer. The best example of a biomarker detected in the urine after a vigorous digital rectal examination is PCA3, which is used mainly in the subgroup of patients with PSA 4–10 ng/mL whose prostate biopsy was repeatedly negative for prostate cancer in order to decide the performance or not of a new biopsy. Proteomics is a state of the art new biotechnology used to identify the proteome of a certain tissue meaning the whole group of proteins related to the anatomy and biochemistry of the tissue. Using proteomics can effectively and more specifically identify proteins that can be used as potential biomarkers for the early diagnosis of prostate cancer. Zinc α2-glycoprotein has been studied in the past as a protein related to cancer cachexia and it has been measured in both prostate tissue and serum in patients with prostate cancer. Zinc α2-glycoprotein has also been recently identified by proteomics in prostate tissue showing different values in patients with prostate cancer and benign prostate hyperplasia. It is the first time that zinc α2-glycoprotein has been systematically measured and studied in an easily obtained biological fluid such as urine showing a very optimistic potential both as a novel solo biomarker and as an adjunct to PSA for the early diagnosis of prostate cancer.
PSA has revolutionized the way we approximate prostate cancer diagnosis. Even though PSA is still the best biomarker for the diagnosis of prostate cancer it constitutes an organ-specific and not a disease-specific biomarker and diagnostic dilemmas are often raised concerning the performance or not of a prostate biopsy. Thus novel biomarkers are required in order to improve the diagnostic ability of PSA. Increasingly in the literature it is stated that the future of prostate cancer diagnosis could be not a single biomarker but a band of different biomarkers that as a total could give the possibility of an individual having prostate cancer. By detecting and measuring zinc α2-glycoprotein in the urine we believe that interesting conclusions can be made: first that proteomics is the way to detect with accuracy proteins that could be proved to be valuable novel biomarkers; second that zinc α2-glycoprotein detected in the urine could be used both as a solo biomarker and as an adjunct to PSA for the early diagnosis of prostate cancer.