Percent free prostate-specific antigen values in men with recurrent prostate cancer after radical prostatectomy.

OBJECTIVES: Patients with prostate cancer may have more of the complexed form of prostate-specific antigen (PSA) in the serum, whereas patients with benign prostatic hyperplasia have less of this complexed form and thus a higher proportion of the free form. However, the molecular basis for the lower percent of free PSA in patients with prostate cancer remains unknown, and considerable overlap in values exists. We examined this hypothesis in men with recurrent or persistent cancer after radical prostatectomy. These men, who have "pure" cancer in that they have no benign elements to their disease, should have very low percent free PSA values. METHODS: Forty-six men with recurrent (persistent) cancer as manifested by rising PSA values (mean [+/-SD] 2.4 +/- 2.5 ng/mL) after radical prostatectomy were available for analysis. Specimens were analyzed with the use of the Abbott AxSYM free and total PSA assays. The Mann-Whitney U test was used to compare percent free PSA values in this recurrent cancer group with values from a previously defined population of 413 men (225 with benign disease and 188 with prostate cancer before prostatectomy). RESULTS: Median values of percent free PSA in the recurrent cancer group (8.4%) were significantly lower than values in the preoperative cancer (11.7%) or benign (17.4%) groups (P < 0.0001 for both comparisons). Among patients in the "pure" cancer group, 30 (65%) had values less than 10%; however, 4 patients (9%) had values from 1 5% to 1 9%, and another 4 (9%) had values of 20% or greater. Pathologically, patients with higher values (15% or greater) had aggressive disease. All patients with values of 20% or greater had evidence of seminal vesicle involvement or nodal disease. CONCLUSIONS: Although most cancers exhibit low values of percent free PSA, a significant proportion of aggressive tumors will demonstrate high values. Until this latter phenomenon can be explained, the widespread use of percent free PSA to distinguish benign from malignant disease or to stage confirmed malignant disease should be approached with caution.

Variations in Valsalva leak point pressure with increasing vesical volume.

PURPOSE: Although leak point pressure testing is a valuable tool in the diagnosis of female stress urinary incontinence, little standardization in methodology exists. We examined the effect of vesical volume on leak point pressure to assess the need for determining an optimal volume for leak point pressure testing. MATERIALS AND METHODS: Video urodynamic testing was performed in 52 consecutive women with a mean age of 52 years who presented with stress urinary incontinence. By fluoroscopic criteria stress urinary incontinence was type I in 12 patients, type II in 20 and type III in 20. Leak point pressure determined at 50 cc volume increments was correlated with fluoroscopic criteria. RESULTS: Women with type I stress urinary incontinence had high leak point pressure, which remained high at increasing vesical volumes, and those with type III had low leak point pressure, which remained low at increasing volumes. In patients with type II incontinence initially high leak point pressure decreased significantly at increasing vesical volumes. The most appropriate classification of patients occurred at a volume of 250 to 300 cc. CONCLUSIONS: Leak point pressure is affected by vesical volume. At a volume of 250 to 300 cc leak point pressure correlates best with fluoroscopic findings, and it may be used to guide therapy in women presenting with stress urinary incontinence.

A model for the number of cores per prostate biopsy based on patient age and prostate gland volume.

PURPOSE: The systematic sextant biopsy is currently the gold standard for the tissue diagnosis of prostate cancer. However, it is unknown whether this 6 core approach provides optimal sampling of all prostate glands in men of all ages. The goal of the current study was to determine the appropriate number of cores per prostate biopsy based on patient age and prostate gland volume. MATERIALS AND METHODS: Patient age and tumor volume doubling time were used to calculate life threatening, clinically significant tumor volumes at diagnosis for 5-year intervals of patient age. A mathematical model was created to determine the minimum number of cores necessary to identify these life threatening tumor volumes in prostate glands 10 to 80 cm.3 without detecting clinically insignificant cancers. RESULTS: Younger men and men with larger prostate glands require more than 6 cores to ensure the diagnosis of life threatening prostate cancer. These prostates are currently under sampled by sextant biopsy. In a select group of older men who require fewer than 6 cores sextant biopsy may over sample these prostates and lead to over treatment. CONCLUSIONS: The standard sextant biopsy provides optimal sampling of only a minority of prostate glands. An approach to prostate biopsy based on patient age and prostate gland volume maximizes the detection of clinically significant prostate cancer.

Percent free prostate-specific antigen: entering a new era in the detection of prostate cancer.

The introduction of prostate-specific antigen (PSA) testing into clinical medicine in 1986 revolutionized the management of patients with prostate cancer. The major limitation of this tumor marker stems from its inability to provide a clear distinction between benign prostate disease and prostate cancer, especially in patients with upper limit of normal or slightly increased PSA values. Recent research has established that PSA exists in the serum in several molecular forms. Patients with benign prostatic hyperplasia have more of the free form, whereas those with prostate cancer have more of a complexed form (PSA covalently bound to alpha 1-antichymotrypsin). Several investigations have now confirmed that determining percent free PSA (proportion of free PSA to total PSA) enhances the ability of PSA testing to distinguish between prostate cancer and benign prostatic hyperplasia. In addition, percent free PSA seems to have the greatest clinical significance in patients whose total PSA values range from 2.5 or 3.0 ng/mL (lower limit) to 10.0 ng/mL (upper limit). When the total PSA value is in the normal range (2.5 or 3.0 to 4.0 ng/mL), percent free PSA makes PSA a more sensitive test (increases cancer detection). When the total PSA level is minimally increased (4.1 to 10.0 ng/mL), percent free PSA makes PSA a more specific test (eliminates performance of unnecessary prostate biopsies). Although further work remains, it seems that percent free PSA can substantially improve the clinical utility of the PSA test for detecting early, curable prostate cancer.

Determination of the "reflex range" and appropriate cutpoints for percent free prostate-specific antigen in 413 men referred for prostatic evaluation using the AxSYM system.

OBJECTIVES: Prostate-specific antigen (PSA) exists in the serum in two clinically important molecular forms: free PSA and PSA complexed to alpha 1-antichymotrypsin. Total PSA approximates the sum of the free and complexed forms. Preliminary investigations have illustrated the potential benefits of using percent free PSA to enhance the clinical utility of PSA in distinguishing benign prostate disease from prostate cancer. The current study defines the optimal range of total PSA for measuring percent free PSA (reflex range) and generates appropriate cutpoints for percent free PSA within this range. METHODS: A total of 413 patients, 225 (54%) with benign prostate disease (mean age, 67 years) and 188 (46%) with prostate cancer (mean age, 66 years), who had PSA values between 2.0 and 20.0 ng/mL participated in the investigation. All patients underwent a sextant biopsy to establish the diagnosis. The serum specimens were assayed with the AxSYM PSA assay (total PSA) and AxSYM Free PSA assay (Abbott Laboratories; Abbott Park, IL). Percent free PSA was calculated for all patients. Receiver operating characteristic (ROC) curves were generated for various ranges of total PSA to determine the reflex range that maximized the increase in sensitivity and specificity of percent free PSA over total PSA. Within the optimal range, the ROC curves were utilized to generate cutpoints for percent free PSA to be used in clinical practice. RESULTS: The appropriate reflex range for the utility of percent free PSA was 3.0 to 10.0 ng/mL. The appropriate cutpoint for percent free PSA when the total PSA value was 3.0 to 4.0 ng/mL to achieve 90% sensitivity for the detection of prostate cancer was 0.19. This approach resulted in a biopsy rate of 73% and a cancer detection rate of 44% in men with a total PSA value between 3.0 and 4.0 ng/mL. The appropriate cutpoint for percent free PSA when the total PSA value was 4.1 to 10.0 ng/mL to ensure 95% sensitivity for detection of prostate cancer was 0.24. Within the range of 4.1 to 10.0 ng/mL, this approach resulted in 13% fewer negative biopsies and failure to detect 5% of the cancers. CONCLUSIONS: Percent free PSA should be utilized in patients with a total serum PSA value between 3.0 and 10.0 ng/mL. In patients with a total PSA value between 3.0 and 4.0 ng/mL, percent free PSA enhanced the detection of prostate cancer (improving sensitivity). In patients with a total PSA concentration ranging from 4.1 to 10.0 ng/mL, negative biopsies were eliminated (improving specificity).