Free prostate-specific antigen improves prostate cancer detection in a high-risk population of men with a normal total PSA
and digital rectal examination.
The uPM3 test had 66% sensitivity and 88% specificity in diagnosing prostate cancer in patients with a total PSA
level of 4 ng/mL or higher.
Of 443 patients who had a total PSA
level available, 152 (34%) had a positive biopsy, Positive biopsies occurred in 20.2% of men who had a total PSA
level less than 4 ng/mL, 34.9% of men with total PSA
of 4-10 ng/mL, and 44.3% of men with total PSA
above 10 ng/mL.
Earlier studies focusing on the elimination of total PSA
found the half-life to be 2.2 [+ or -] 0.8 days(23) to 3.2 [+ or -] 0.1 days.(24) When separate analyses of free and total PSA
became possible, it was reported that the clearance of free and total PSA
after radical prostatectomy could be explained by a "two compartment" model, based on size of the PSA molecule and receptor interaction with antiproteases.
The authors have studied the practice of "reflexive" ordering of percent free prostate-specific antigen (PSA) in patients that have a total PSA
value between 4 and 10 ng.[sup.1] This ordering is standard procedure at their tertiary care centre and possibly across other centres.
Furthermore, the PCA3 score has been reported to correlate with tumor volume, but not with prostate volume or the total PSA
concentration in serum.
LOS ANGELES -- A low level of free prostate-specific antigen relative to total PSA
may be a marker for patients with more advanced prostate cancer, Dr.
Sokoll, PhD, and colleagues at Johns Hopkins Medical Institution in Baltimore, report that in the 2.5 ng/mL to 4.0 ng/mL total PSA
range, potentially 75 percent of cancers can be detected, with 59 percent of unnecessary biopsies being spared, using percentage of pPSA, as compared to only 33 percent of biopsies being spared using percentage of fPSA.
Using these antibodies (along with a polyclonal to [[alpha].sub.1]-antichymotrypsin), we developed the first assays specific for the major PSA forms in serum, including an assay that uniquely recognized the free uncomplexed PSA form and an assay for total PSA
that in an approximately equimolar manner measured the sum of free PSA and PSA in complex with [[alpha].sub.1]-antichymotrypsin.
One study included 316 men who had serum total PSA
levels of 2.6-4.0 ng/mL at the time of' enrollment.
In one study, 316 men had serum total PSA
levels of 2.6-4.0 ng/mL at enrollment.
The study also showed that the cPSA test and the total PSA
test are comparable in their ability to detect prostate cancer when they are used in combination with DRE.