OBJECTIVES: To determine the clinical utility of using proenzyme prostate-specific antigen (pPSA) for early detection of prostate cancer in the 2.5 to 4.0 ng/mL total PSA range. pPSA, the precursor form of PSA that contains a 7 amino acid leader peptide, and truncated forms such as [-2]pPSA and [-4]pPSA can be measured in serum by research immunoassay. METHODS: Archival serum from 119 men (noncancer, 88; cancer, 31), obtained before biopsy and in the total PSA range of 2.5 to 4.0 ng/mL, were assayed for total PSA, free PSA (fPSA), and pPSA. pPSA was defined as the sum of the [-2], [-4], and [-7] forms, and the percent pPSA (%pPSA) was defined as pPSA/fPSA. RESULTS: pPSA averaged 4.6% +/- 0.4% (SEM) of total PSA and 39.3% +/- 3.5% of fPSA. PSA and %fPSA values were similar between the noncancer and cancer groups, and %pPSA tended to be higher in the cancer group (50.1% +/- 4.4%) compared with the noncancer group (35.5% +/- 6.7%; P = 0.07). Using receiver operating characteristic analysis to assess clinical utility, the area under the curve for %pPSA was 0.688 compared with 0.567 for %fPSA. At a fixed sensitivity of 75%, the specificity was significantly greater for %pPSA at 59% compared with %fPSA at 33% (P <0.0001). CONCLUSIONS: In the 2.5 to 4.0 ng/mL total PSA range, 75% of cancers can potentially be detected with 59% of unnecessary biopsies being spared using %pPSA; use of %fPSA would result in sparing only 33% of unnecessary biopsies. A large prospective clinical trial is needed to confirm these preliminary findings.
OBJECTIVES: To determine the clinical utility of using proenzyme prostate-specific antigen (pPSA) for early detection of prostate cancer in the 2.5 to 4.0 ng/mL total PSA range. pPSA, the precursor form of PSA that contains a 7 amino acid leader peptide, and truncated forms such as [-2]pPSA and [-4]pPSA can be measured in serum by research immunoassay. METHODS: Archival serum from 119 men (noncancer, 88; cancer, 31), obtained before biopsy and in the total PSA range of 2.5 to 4.0 ng/mL, were assayed for total PSA, free PSA (fPSA), and pPSA. pPSA was defined as the sum of the [-2], [-4], and [-7] forms, and the percent pPSA (%pPSA) was defined as pPSA/fPSA. RESULTS: pPSA averaged 4.6% +/- 0.4% (SEM) of total PSA and 39.3% +/- 3.5% of fPSA. PSA and %fPSA values were similar between the noncancer and cancer groups, and %pPSA tended to be higher in the cancer group (50.1% +/- 4.4%) compared with the noncancer group (35.5% +/- 6.7%; P = 0.07). Using receiver operating characteristic analysis to assess clinical utility, the area under the curve for %pPSA was 0.688 compared with 0.567 for %fPSA. At a fixed sensitivity of 75%, the specificity was significantly greater for %pPSA at 59% compared with %fPSA at 33% (P <0.0001). CONCLUSIONS: In the 2.5 to 4.0 ng/mL total PSA range, 75% of cancers can potentially be detected with 59% of unnecessary biopsies being spared using %pPSA; use of %fPSA would result in sparing only 33% of unnecessary biopsies. A large prospective clinical trial is needed to confirm these preliminary findings.
Authors: Yuanyuan Liang; Donna P Ankerst; Norma S Ketchum; Barbara Ercole; Girish Shah; John D Shaughnessy; Robin J Leach; Ian M Thompson Journal: J Urol Date: 2010-11-12 Impact factor: 7.450
Authors: Brian V Le; Christopher R Griffin; Stacy Loeb; Gustavo F Carvalhal; Donghui Kan; Nikola A Baumann; William J Catalona Journal: J Urol Date: 2010-02-19 Impact factor: 7.450
Authors: Lori J Sokoll; Martin G Sanda; Ziding Feng; Jacob Kagan; Isaac A Mizrahi; Dennis L Broyles; Alan W Partin; Sudhir Srivastava; Ian M Thompson; John T Wei; Zhen Zhang; Daniel W Chan Journal: Cancer Epidemiol Biomarkers Prev Date: 2010-05 Impact factor: 4.254
Authors: Jeffrey J Tosoian; Stacy Loeb; Zhaoyong Feng; Sumit Isharwal; Patricia Landis; Debra J Elliot; Robert Veltri; Jonathan I Epstein; Alan W Partin; H Ballentine Carter; Bruce Trock; Lori J Sokoll Journal: J Urol Date: 2012-08-15 Impact factor: 7.450
Authors: Danil V Makarov; Sumit Isharwal; Lori J Sokoll; Patricia Landis; Cameron Marlow; Jonathan I Epstein; Alan W Partin; H Ballentine Carter; Robert W Veltri Journal: Clin Cancer Res Date: 2009-11-24 Impact factor: 12.531