The incidence of prostate cancer in a screening population with a serum prostate specific antigen between 2.5 and 4.0 ng/ml: relation to biopsy strategy.

PURPOSE: It has recently been suggested that the diagnostic threshold for the prostate specific antigen (PSA) assay be lowered to enhance prostate cancer detection. A 22% incidence of prostate cancer has been reported in men with PSA between 2.5 and 4.0 ng/ml. We designed a study to confirm this observation. MATERIALS AND METHODS: Men who participated in our free early detection program and who had serum PSA between 2.5 and 4.0 ng/ml were asked to undergo prostate biopsy. Of 268 eligible men 151 (56%) agreed to participate in this free trial. All men underwent biopsy using an 11-core multisite directed biopsy scheme. All biopsy cores were color coded for location specificity and examined by 1 pathologist. RESULTS: Cancer was identified in 24.5% (37 of 151) of the men biopsied. The median age of men with cancer was 62 years (range 43 to 74). Conventional systematic sextant biopsies, which accounted for 6 of the 11 cores, detected 73.0% (27 of 37) of the cancers and the alternate site biopsies identified the remaining 10. Gleason score was 6 in 25 men, 3 + 4 in 5, 4 + 3 in 4 and 8 or greater in 3 (median Gleason score 6). There were 14 men who had 1 core positive for cancer, 9 had 2 and 14 had more than 2 (median number of positive cores 2). Of the 14 men with 1 positive core 11 had a less than 3 mm focus of cancer and 8 had only a positive alternate site biopsy. There were 11 cases of abnormal results on digital rectal examination, 5 of which were cancer, and 31 cases of abnormal results on ultrasonography, 13 of which were cancer. Median biological variability in PSA was +/-15% (range 0.4% to 440.0%). CONCLUSIONS: We found a significant incidence of cancer (24.5%, 37 of 51) in men with serum PSA between 2.5 and 4.0 ng/ml. In our study 67.6% of the detected cancers were significant based on the biopsy data. If the PSA threshold is lowered the conventional systematic sextant technique may be preferable to an extended strategy.

Performance of a neural network in detecting prostate cancer in the prostate-specific antigen reflex range of 2.5 to 4.0 ng/mL.

OBJECTIVES: To explore the potential role of a neural network-derived algorithm in enhancing the specificity of prostate cancer detection compared with the determination of prostate-specific antigen (PSA) and free PSA (fPSA) while maintaining a 90% detection rate. Recent information suggests that the incidence of detectable prostate cancer is similar in men whose PSA values range from 2.5 to 4.0 ng/mL and from 4.0 to 10.0 ng/mL. If the PSA threshold triggering a prostate biopsy is lowered to 2.5 ng/mL, approximately 13% of men older than 50 would be added to the patient biopsy pool. METHODS: One hundred fifty-one men were enrolled in a prospective, Institutional Review Board-approved protocol to evaluate the incidence of cancer in a population of men who participated in an early-detection program and whose PSA level was between 2.5 and 4.0 ng/mL. All the men underwent biopsy using an 11-core multisite-directed biopsy scheme, and all biopsy specimens were examined by one pathologist. All men had a second blood specimen drawn before the biopsy for a determination of serum PSA, creatinine kinase, prostatic acid phosphatase, and fPSA. A new neural network algorithm was developed with PSA, creatinine kinase, prostatic acid phosphatase, fPSA, and age as input variables to produce a single-valued prostate cancer detection index (PCD-I). This new algorithm was then prospectively tested in the 151 men. Performance parameters (including sensitivity, specificity, positive and negative predictive values, and biopsies saved) were calculated, and a comparative analysis was performed to evaluate the differences among the new algorithm, percent fPSA, PSA density, and PSA density-transition zone. RESULTS: Cancer was histologically confirmed in 24.5% (37 of 151) of the men. The median age of the men was 62 years (range 43 to 74). At a sensitivity of 92%, the specificity for percent fPSA was 11%. The new algorithm (PCD-I) demonstrated an additional enhancement of specificity to 62% at 92% sensitivity. Clinically, the PCD-I would result in a savings of 49% (74 of 151) of all biopsies or 63.6% (71 of 114) of all unnecessary biopsies. CONCLUSIONS: A new generation algorithm, derived from a neural network (PCD-I) incorporating the parameters of age, creatinine kinase, PSA, prostatic acid phosphatase, and fPSA can significantly enhance the specificity and reduce the number of biopsies while maintaining a 92% sensitivity rate.

Gravimetric determination of urine volumes.

A procedure for estimating urine volumes from urine weights is presented. Regression analysis was used to assess correlation between weight-volume errors. The urine weight was divided by 1.016, the mean urine specific gravity in our patient population. It was found that the gravimetric method gave results lower than the volume method by one percent or less. We conclude that this difference is acceptable for clinical purposes. The gravimetric procedure has the advantages of rapidity, cost-effectiveness, and safety.

Comparison of rates of hydrolysis of N-oleoyl and N-stearoyl glucocerebroside in patients with Gaucher's disease.

The deficiency of oleic acid as one of the fatty acids in glucocerebrosides that accumulate (31--77 mg/g dry weight) in the spleen in patients with Gaucher's disease was confirmed in 9 cases. In an effort to account for the 10-fold difference between the oleoyl glycocerebroside content of glucocerebrosides in spleen from controls and patients with Gaucher's disease, we compared the ability of extracts of spleen and fibroblasts from individuals with various forms of Gaucher's disease and controls to hydrolyze [14C]stearoyl and [3H]oleoyl glucocerebroside. The residual glucosylceramidase activity in patients with Gaucher's disease hydrolyzes the glucose moiety of oleoyl glucocerebroside at approximately the same rate as that of stearoyl glucocerebroside. Similarly, the more active glucosylceramidase of control tissue acts upon both oleoyl and stearoyl glucocerebrosides with equal efficiency. These observations indicate that a mutation affecting the substrate specificity of glucosylceramidase cannot account for the lack of oleic acid-containing glucocerebrosides in patients with Gaucher's disease. Thus, the hypothesis that the difference in fatty acid composition found in glucocerebroside is obtained as a result of a mutation affecting the specificity of the residual glucosylceramidase must be rejected.

Effect of pentadecan-2-one on lipid metabolism in HeLa cells.

HeLa cells exposed to trace amounts of pentadecan-2-one showed changes in metabolism of 1(-14)C-palmitate. These changes consisted of an increased incorporation of radioactivity into the triglycerides and free fatty acids and a decreased 14C incorporation into the ether moiety of alk-1-enyl acyl phosphoglycerides. Chemical analysis of the several lipid fractions showed a threefold increase in triglyceride content but no change in the amount of alk-1-enyl acyl or diacyl phosphoglycerides in the treated cells. Pentadecan-2-one added to the culture medium apparently gains entrance to the cell since both pentadecan-2-one and pentadecan-2-ol were detected in the ketone-treated cells and their culture medium.

Characterization and tissue distribution of 6-O-beta-D-galactopyranosyl myo-inositol in the rat.

A disaccharide was isolated from rat mammary tissue and determined to be 6-O-beta-galactopyranosyl myo-inositol (6-beta-galactinol) on the basis of combined gas-liquid chromatography-mass spectrometry of the permethylated and peracetylated derivatives as well as previously reported chemical and enzymatic evidence. 6-beta-Galactinol, also found in rat milk, increased during lactation, and on the 18th day represented approximately 17% of the total non-lipid neutral myo-inositol. The sugar was absent in all other rat tissues examined, suggesting a unique association with the process of lactation. This novel galactoside of one human subject on the basis of paper and gas-liquid chromatography.