PSA Velocity PSAV

PSA-V is the rate of change in serum PSA over time. PSA-V = 1/2 ((PSA2-PSA1/t1 in years) + (PSA3 - PSA2/t2 in years)), where PSA1 is the first, PSA2 the second and PSA3 the third PSA measurement. Time represents the interval (in years) between PSA measurements. It is recommended that three PSA measurements obtained over 24 months yields optimal accuracy. A PSA-V exceeding 0.75 ng/ml/year is highly predictive of prostate cancer. PSA-V is more useful than PSA doubling time (PSA-DT) in the pretreatment setting to help identify those men with life-threatening disease [14].

Studies confirm that the PSA tumor marker reflects prostate tumor growth and PSA dynamic changes are useful for predicting clinical outcome in several situations such as tumor recurrence and overall survival [15].

Klotz [16] reviewed the value of PSA as a tumor marker in patients with prostate cancer. He noted that use of a single serum value of PSA is inadequate for predicting patient survival. However, the PSA-V as ng/ml/yr. was a marker of disease biology. D'Amico [17] included preoperative PSA-V in determining subsequent risk of death from prostate cancer in 1095 men with clinically localized prostate cancer that underwent prostatectomy and radiation therapy [18]. A PSA-V >2 ng/ml/yr the year before prostatectomy, was associated with lymph node metastases, an advanced pathologic stage, and high-grade disease. This threshold level of PSA-V was associated with a significantly shortened time to recurrence, death from prostate cancer, and death from any cause. Strikingly, men with a PSA rise of >2.0 ng/ml had prostate cancer-specific mortality rates nine times those with a PSA-V <2 ng/ml.

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