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PSA vs. PCA3 in Prostate Cancer

Prostate Specific Antigen (PSA) testing is most commonly used to determine the health of the prostate gland and can be tested simply through a blood test. For a long time now, high PSA levels have shown to be correlated with prostate cancer. However, PSA levels can also be equally elevated in other non-cancerous conditions such as: Benign Prostate Hypertrophy (BPH), urinary tract infections and prostate infections (acute and chronic prostatitis). So, if PSA levels can be elevated in a variety of conditions, how would you know if your high PSA levels are due to cancer or another prostate condition? The answer is – you don’t know, without having a biopsy. Biopsy is the ONLY DEFINITIVE way to diagnose a specific cancer.

There is another laboratory test that is being used around the globe. The Prostate Cancer Antigen 3 (PCA3) test has been shown to be effective in helping patients/doctors come to a biopsy decision, investigate further for an initial cancer diagnosis and even monitor the progression of cancer numerically while undergoing active treatments. The PCA3 test is not a blood test. A digital rectal examination (DRE) is performed by the doctor – the purpose being to mobilize PCA3 from the prostate into the urine. Immediately following the DRE, first-urine is collected. This first-urine is rich in PCA3 and is sent to the laboratory for quantifiable testing.

The PCA3 test measures PSA as well and the ratio between PCA3 and PSA. There is a cut off numerical marker that determines a higher likelihood of cancer diagnosis. The PCA3 is a highly specific test for prostate cancer and is specific to prostate cancer alone. No other prostate condition would yield elevated PCA3 levels, other than prostate cancer.

Upon PCA3 testing, most patients with elevated PCA3 levels who used this information to go ahead with biopsy, were diagnosed with prostate cancer. The PCA3 test is a really helpful test to aid patients (and their doctors) in making a decision of whether or not they wish to undergo a biopsy or not. This test is also great for patients who have been asked to take the “wait and watch” approach by their medical doctor, since high PSA levels do not necessarily mean cancer. Doing this test periodically during the “wait and watch” period can help determine whether or not a biopsy is warranted or if the cancer burden on the body is increasing.

Please note: The most definitive way to diagnose cancer is through a biopsy. More studies are needed on PCA3 testing in the diagnoses and management of prostate cancer, however PCA3 testing is beginning to be used as a part of prostate cancer evaluation across the globe.

Yours in Health,

Dr. Mawji

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