Percentage of free serum prostate-specific antigen as a predictor of pathologic features of prostate cancer in a screening population.

OBJECTIVES: Measurement of the percentage of free prostate-specific antigen (%FPSA) in serum can improve the specificity of prostate cancer screening. We evaluated the ability of %FPSA to predict pathologic features of screen-detected clinically localized prostate cancer. METHODS: We evaluated the correlation between %FPSA in serum before cancer diagnosis and the pathologic features of the cancers detected in 108 men with clinically localized prostate cancer who were treated with radical prostatectomy and for whom complete embedding of the radical prostatectomy specimen was performed. Ninety-seven men (90%) had a previous negative screening evaluation before prostate cancer was detected. RESULTS: There was a negative correlation of %FPSA with penetration of cancer through the prostatic capsule, cancerous surgical margins, Gleason score, percentage of cancer in the gland, and tumor volume (r = -0.2 to -0.4). After controlling for other preoperative predictors, %FPSA predicted capsular penetration (adjusted odds ratio [OR] 1.6, 95% confidence interval [CI] 1.1 to 2.4, for each 5% decrease in %FPSA) and cancer volume 0.5 cc or greater (adjusted OR 1.6, 95% CI 1.1 to 2.3). Preoperative %FPSA also predicted possibly harmless cancer (OR 1.5, 95% CI 1.1 to 2.2, for each 5% increase in %FPSA). CONCLUSIONS: In a select group of men for whom cancer was detected early via screening, a lower %FPSA in serum suggests a potentially more threatening cancer. This information may aid patients and clinicians in making more informed decisions about the management of prostate cancer, such as selecting patients for watchful waiting. However, more research is needed to determine the performance characteristics of %FPSA in clinical practice.

Stability of serum total and free prostate specific antigen under varying storage intervals and temperatures.

PURPOSE: Measurement of total serum prostate specific antigen (PSA) is widely used as an aid to early detection of prostate cancer. Measurement of the ratio of free-to-total PSA (percentage of free PSA) may help increase specificity of PSA testing. We prospectively studied the effects of varying the storage temperature and interval on total and free PSA levels. MATERIALS AND METHODS: We measured the baseline total and free serum PSA levels in 36 volunteers (mean age 66 years) and then retested aliquots of these serum samples after varying storage intervals (24 hours, 2 weeks and 9 months) at 3 different temperatures (4C, -20C and -70C). Volunteers represented a spectrum of prostatic conditions (PSA levels 2.0 to 4.0 ng./ml., PSA levels greater than 4.0 ng./ml. without cancer and PSA levels greater than 2.0 ng./ml. with prostate cancer). We used repeated measures analysis of variance to test for changes in total and free PSA levels as a function of time and temperature. We also evaluated the impact of storage at different temperatures and times on the percentage of free PSA. RESULTS: Across groups total and free serum PSA decreased from the baseline level differentially as a function of longer storage interval and higher temperature (p <0.05). No significant difference was found for change in total PSA at 24 hours, 2 weeks or 9 months for storage temperatures of -20C compared with -70C. A significant change from baseline level was found for free PSA when stored in -20C compared with -70C for 2 weeks but the magnitude of the change was modest. CONCLUSIONS: For storage intervals up to 9 months total PSA is more stable than free PSA under temperature conditions ranging from 4C to -70C. This differential stability has important implications for the clinical evaluation of percentage of free PSA to distinguish between benign and malignant diseases of the prostate.

Prostate-specific antigen as a screening test for prostate cancer. The United States experience.

Serum PSA-based early detection for prostate cancer has been studied fairly extensively for the past several years. It appears that we can state fairly categorically what the relative performances of total serum PSA, DRE, and TRUS are in detecting early-stage prostate cancer; that initial screening is effective in detecting histologically significant and pathologically organ-confined prostate cancer; that annual, serial, repetitive screening, at least over a 4- to 5-year horizon, does not overdetect prostate cancer, and that the results of early detection will improve as our ability to use certain PSA transformations such as PSA density, PSA slope, age-specific PSA adjustment, and knowledge of free versus total serum PSA is better characterized. These advances in our ability to diagnose early-stage prostate cancer likely will be coupled with an increased ability to predict the behavior, curability, and significance of individual tumors. It is hoped that information soon will be available to allow physicians to categorize an individual tumor as insignificant, significant and surgically curable, or significant and incurable by standard approaches. This ability, coupled with the demonstrated ability to detect prostate cancer, will make an even more compelling argument for widespread PSA-based screening. At present, annual DRE and total serum PSA measurements are recommended for men older than 50 and among younger men at high risk for prostate cancer. All suspicious DRE findings should be evaluated with prostatic biopsy. Among younger men, PSA levels over 2.5 ng/mL should be considered worrisome and further evaluated. For men older than 65, serum PSA levels above 4 ng/mL should be considered abnormal and warrant biopsy. Men with persistent serum PSA elevation and a negative biopsy should undergo repeat biopsy at least once, and perhaps more often if PSA slope exceeds 0.75 per year, if density is greater than 0.10, or if f-PSA is less than 20%.

Renal masses: urologic management.

This article reviews the differential diagnoses for solid renal masses and staging for renal cell carcinoma, and also discusses several areas of controversy in regard to the management of solid renal masses, such as the role of nephron-sparing surgery, extended lymphadenectomy, and ipsilateral adrenalectomy. The management of renal cell carcinoma associated with tumor thrombus within the vena cava is discussed, as are issues regarding both surgical and medical management (including chemotherapy and immunotherapy) of metastatic disease. Lastly, the emerging role of laparoscopic nephrectomy is examined.