Serum Percent–Free PSA Does Not Predict Extraprostatic Spread of Prostate Cancer

Abstract

Percent-free prostate-specific antigen (proportion of free prostate-specific antigen [PSA] to total PSA) has been shown recently in studies on frozen serum samples to be more useful than total PSA alone in distinguishing prostate cancer from benign conditions of the prostate gland. The primary purpose of our study was to determine whether percent-free PSA could predict extraprostatic spread of prostate cancer. We also sought to evaluate the freeze-thaw stability of free PSA. Percent-free PSA values in fresh serum samples were compared with those in aliquots subjected to one to five freeze-thaw cycles. Percent-free PSA values in frozen serum samples from 130 men undergoing Prostate-specific antigen (PSA) is a 33-kd serine protease secreted almost exclusively by prostatic columnar epithelial cells.1 Serum PSA is the best and most widely used tumor marker for the early diagnosis and m a n a g e m e n t of prostate cancer.2 -5 Another major use of PSA is monitoring for recurrence in patients after radical prostatectomy; a detectable serum PSA value is a most sensitive indicator of residual or recurrent disease. 6 ' 7 PSA has proven to be less useful in preoperative staging of clinically localized prostatic adenocarcinoma,

Measurement of free PSA in the diagnosis and staging of prostate cancer

“…In a study of 288 patients with clinically localized prostate cancer who underwent radical prostatectomy, 97.2% had less than 25% free PSA and no relation was found between this parameter and the pathological stage (Partin et al, 1996). In another study carried out on 70 patients, the conclusion was that the percentage of free PSA did not predict whether adenocarcinoma had spread beyond the prostate gland (Henricks et al, 1996). In the present series of 118 patients with prostate cancer, we found that the percentage of free PSA was not related to clinical stage, although the group of patients with metastatic disease showed a significantly lower ratio, p , 0.04.…”

Human Tissue Kallikrein 5 Is a Member of a Proteolytic Cascade Pathway Involved in Seminal Clot Liquefaction and Potentially in Prostate Cancer Progression

“…M, molecular mass standards with shown masses in kilodaltons. (37)(38)(39). By using a polyclonal antibody against hK3, we performed Western blots of seminal plasma, prostate extracts and at different time points of the activation of pro-hK3 by hK5.…”

Free Prostate-Specific Antigen:Does It Measure Up?

“…Their study population consisted of men undergoing radical prostatectomy for prostate cancer, 44% of w h o m d e m o n s t r a t e d extraprostatic spread of the tumor. Total PSA values were significantly different b e t w e e n the organconfined and extraprostatic groups, but there was no significant difference in percent-free PSA (see Fig 1 and 2 in Henricks et al article 1 ). Inspection of these figures reveals a large overlap of values between the two groups; there is no decision level that would provide a reasonable sensitivity and specificity for either total PSA or percent-free PSA (see Fig 5 in Henricks et al article 1 ).…”

“…Total PSA values were significantly different b e t w e e n the organconfined and extraprostatic groups, but there was no significant difference in percent-free PSA (see Fig 1 and 2 in Henricks et al article 1 ). Inspection of these figures reveals a large overlap of values between the two groups; there is no decision level that would provide a reasonable sensitivity and specificity for either total PSA or percent-free PSA (see Fig 5 in Henricks et al article 1 ). Percent-free PSA also failed to predict the pathologic stage of the tumors and was only weakly correlated to the Gleason score.…”

“…It is this q u e s t i o n that H e n r i c k s a n d colleagues 1 have addressed. Their study population consisted of men undergoing radical prostatectomy for prostate cancer, 44% of w h o m d e m o n s t r a t e d extraprostatic spread of the tumor.…”