Comparison of prostate size in university and Veterans Affairs Health Care System patients with negative prostate biopsies

OBJECTIVES

Many important prostate studies take place at Veterans Affairs hospitals. We have examined whether the patient population at these institutions is comparable to the population presenting for prostate evaluation at university hospitals.

METHODS

We included all patients presenting for transrectal ultrasound (TRUS) and biopsy in whom systematic biopsies failed to reveal prostate cancer at both Stanford University Medical Center (90 patients) and the Palo Alto Veterans Affairs Health Care System (103 patients) from August 1, 1995 to July 31, 1996. Identical techniques and equipment for TRUS examination and prostate size determination were used at both institutions.

RESULTS

There was no significant difference in the age or prostate-specific antigen (PSA) levels of the patients at the two institutions. The mean prostatic volume of the Stanford University patients was 71 cm3 (median 63 cm3), whereas the mean prostatic volume of patients at the Palo Alto Veterans Affairs hospital was 52 cm3 (median 43 cm3), a highly statistically significant difference (P = 0.0009).

CONCLUSIONS

The smaller size of the prostate glands in Veterans Affairs patients may be the result of differences in referral base, socioeconomic factors, or environmental factors. These data may have significance for trials conducted only on the prostates of men who are seen at Veterans Affairs hospitals.

Comparison of mid-lobe versus lateral systematic sextant biopsies in the detection of prostate cancer

OBJECTIVE

Systematic sextant biopsies are a powerful tool in the diagnosis of prostate cancer. Interpretation of the histopathologic results of these biopsies plays a central role in treatment decisions. This biopsy approach was originally described as sampling the prostate in the mid-lobe, parasagittal plane at the apex, mid-gland, and base, bilaterally. Morphometric analysis of prostate specimens has revealed that most clinically significant cancers are mainly located in the posterolateral aspect of the gland, not the mid-lobe. We sought to determine if cancer detection could be improved by obtaining more laterally placed biopsies.

MATERIALS AND METHODS

Forty-one patients underwent transrectal ultrasound with mid-lobe sextant as well as lateral sextant biopsies. Biopsy specimens were evaluated for Gleason grade and length of cancer present in each core. The mid-lobe and lateral biopsy results were then compared.

RESULTS

Thirteen of 41 patients (31.7%) were found to have no cancer on either biopsy set. Cancer was detected by both the mid-lobe and the lateral biopsies in 19 patients (46.3%). In 6 patients (14.6%), only the lateral biopsies revealed cancer, and in 3 patients (7.3%), only the mid-lobe biopsies revealed cancer.

CONCLUSIONS

Laterally-placed systematic sextant biopsies may yield an improved diagnosis rate in patients with palpable nodularity in the lateral aspect of the prostate, patients without any palpable abnormalities but with elevated PSA levels, and in those patients undergoing repeat biopsies.

Serum levels of prostate-specific antigen among Japanese-American and native Japanese men

BACKGROUND

Fourfold to sixfold higher prostate cancer rates in Japanese-American men in the United States compared with Japanese men in Japan have been cited to support a role for environmental risk factors in the etiology of the disease. To examine the hypothesis that part or all of the elevated prostate cancer rates in Japanese-American men may reflect more intensive prostate cancer screening in the United States than in Japan, we compared prostate-specific antigen (PSA) levels in community-based samples of serum from men without prostate cancer.

METHODS

Japanese-American men aged 40-85 years and native Japanese men aged 40-89 years with no history of prostate cancer provided sera, respectively, in the United States from March 1990 through March 1992 (n = 237) or in Japan from January 1992 through December 1993 (n = 3522). Age-specific PSA levels were used to estimate the prevalences of undetected prostate cancer in the two populations.

RESULTS

Age-specific mean PSA levels were significantly lower in Japanese-Americans than in native Japanese (two-sided P<.001). The prevalence of an elevated PSA level increased with age in both populations and exceeded 5% among men aged 60 years or more. Combined with data on prevalence of detected prostate cancer in the two populations, our data suggest that some 10.0% of Japanese-Americans aged 75 years have prostate cancer, with 31% of that fraction remaining undiagnosed. The corresponding estimates in Japan are a total cancer prevalence of 5.4%, of which 81% has not been detected clinically.

CONCLUSIONS

The total cancer prevalence ratio 10.0/5.4 = 1.9 (95% confidence interval = 1.5-2.3) in Japanese-American men compared with Japanese men in Japan suggests an increased risk for Japanese-American men, but of less magnitude than the fourfold to sixfold increase indicated by the incidence data.

Isolation and characterization of free form prostate specific antigen (f-PSA) in sera of men with prostate cancer

PURPOSE

The free uncomplexed form of prostate specific antigen (f-PSA) from prostate cancer sera was partially isolated and characterized because the molecular form of f-PSA in the serum is unknown.

MATERIALS AND METHODS

230 ml. of sera from 59 men with bone metastasis and individual PSA values of >2000 ng./mL were combined and centrifuged for 60 minutes at 30,000 RPM (4C). The sera were fractionated by gel filtration column chromatography (Sephacryl S-200, 2.5 cm. x 92 cm.). Free and complexed PSA in the eluted fractions were isolated by measuring immunoreactivity of PSA (Tosoh AIA-600 assay); f-PSA from 23 separate runs were combined, concentrated and re-chromatographed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to immobilize the isolated proteins onto a nitrocellulose membrane and a polyvinylidene difluoride (PVDF) membrane. Monoclonal antibody (F5) was used to probe PSA on nitrocellulose membrane and the PSA band was detected by Emission Chemoluminescence (ECL) kit. Amino terminal sequence analysis of the isolated f-PSA was performed with a gas-phase sequentor (Applied Biosyntens 4760 A) using the program designed by the manufacturer.

RESULTS

0.5 cc of f-PSA (27,000 ng./mL) was obtained from serums after rechromatography. SDS-PAGE showed one double band around 30 kDa; with ECL technique, one major band at 30-kDa was identified as PSA. The amino terminal sequence analysis of this band showed residue 1 through 9 and 146 through 152.

CONCLUSIONS

In our preliminary experiment, the free form of serum PSA is partially isolated directly from human sera. Amino terminal sequence analysis has shown that serum f-PSA is not a pre-mature or zymogen form of PSA because serum f-PSA has a N-terminus identical to that of seminal fluid PSA. A nicked form of f-PSA is also found in these patient sera.

Endoscopic topical placement of formalin soaked pledgets to control localized hemorrhage due to radiation cystitis

PURPOSE

A useful technique for treating localized bladder hemorrhage secondary to radiation cystitis is described.

MATERIALS AND METHODS

Cotton pledgets soaked in 5% formalin are placed endoscopically onto bleeding foci of the bladder for 15 minutes and then removed.

RESULTS

There was immediate cessation of prolonged bleeding refractory to intravesical saline, alum, prostaglandin E1 and estrogen. No subsequent bleeding was noted during 16 months of followup.

CONCLUSIONS

Topical application of formalin soaked pledgets is an effective method of controlling localized bleeding secondary to radiation cystitis.

Prostate specific antigen in benign prostatic hyperplasia: purification and characterization

PURPOSE

The ratio of free-to-total prostate specific antigen (PSA) in serum is greater in patients with benign prostatic hyperplasia (BPH) than in those with prostate cancer, and it provides a means of partially discriminating these 2 diseases. To understand the molecular mechanism of why the free-to-total PSA ratio is greater in BPH than in prostate cancer we analyzed PSA obtained directly from nodules of BPH tissue.

MATERIALS AND METHODS

PSA from BPH nodule fluids was first purified by gel filtration and ion exchange chromatography. Purified BPH PSA was characterized by gel electrophoresis, enzyme assay and N-terminal sequence analysis of the amino acids.

RESULTS

A single band at 30 kDa. on sodium dodecyl sulfate polyacrylamide gel electrophoresis under nonreducing conditions was identical to that of seminal fluid PSA. Under reducing conditions most BPH PSA was degraded, whereas most seminal fluid PSA existed as an intact molecule. BPH PSA had multiple internal cleavages in addition to the common cleavage site between lysines 145 and 146 of seminal fluid PSA. Cleavage sites at C-terminals of histidine 54 and phenylalanine 57 were also detected. Enzymatic activity studies with different substrates showed that PSA from seminal fluid and BPH nodules had similar specific trypsin-like activity. However, BPH PSA had much lower specific chymotrypsin-like activity than seminal fluid PSA. N-terminal sequence analysis showed that BPH PSA was neither in the pre-proenzyme form (261 amino acids) nor the zymogen proenzyme form (244 amino acids) of PSA, both of which are known precursors of mature PSA (237 amino acids).

CONCLUSIONS

Most PSA in BPH nodules is in the nicked form with low chymotrypsin-like activity. When it leaks into the circulation it will form fewer PSA-antichymotrypsin complexes and more will remain in the free form. We predict that a protease with trypsin-like activity in BPH nodule fluid is probably responsible for the nicked form of BPH PSA. These findings suggest that antibodies produced against PSA in BPH nodules may be useful in discriminating prostate cancer from BPH.

Prostate-specific antigen doubling times in patients who have failed radical prostatectomy: correlation with histologic characteristics of the primary cancer

OBJECTIVES

This study sought to characterize the postoperative prostate-specific antigen (PSA) doubling time and time to biochemical recurrence in patients who have failed radical prostatectomy.

METHODS

Of 539 consecutive patients who underwent radical prostatectomy between 1984 and 1992, postoperative PSA levels in 80 initially became undetectable (less than 0.07 ng/mL) before eventually increasing, as evidenced by rising PSA levels above the residual cancer detection limit of the Tosoh AIA-600 immunoassay run in the ultrasensitive mode (i.e., 0.07 ng/mL or higher). The PSA doubling time and time to biochemical recurrence were calculated for each of the 80 patients and were correlated with the histopathologic variables from the operative specimen.

RESULTS

Postoperative PSA doubling times were predicted by the extent of capsular penetration, percent Gleason grade 4 or 5, lymph node involvement, and tumor volume on univariate analysis and by capsular penetration, percent Gleason grade 4 or 5, lymph node involvement, and patient age on multivariate analysis. Times to recurrence were predicted by the presence of positive margins and percent Gleason grade 4 or 5 in both univariate and multivariate regression models. The PSA doubling time did not correlate with recurrence time. The median PSA doubling time for all patients was 284 days, and the median time to recurrence was 648 days.

CONCLUSIONS

These results demonstrate that PSA doubling time and recurrence time are indicative of different biologic characteristics of recurrent prostate cancer: Doubling time appears to represent the aggressiveness of the original prostate cancer, whereas time to recurrence reflects the extent of residual postoperative disease. This information should aid in the selection of men who need greater vigilance during postoperative surveillance.

Progress in standardization of immunoassays for prostate-specific antigen

A calibrator composed of 90% prostate-specific antigen-alpha 1-antichymotrypsin (PSA-ACT) and 10% free PSA reduces the variation in control serums with widely divergent amounts of free PSA, from a mean of 28% among nine different assays to 9% after recalibration. The lyophilized form of the Stanford 90:10 calibrator is stable and therefore an excellent candidate for international standardization of PSA assays.

Use of serum concentration techniques to enhance early detection of recurrent prostate cancer after radical prostatectomy

OBJECTIVES

We evaluated the clinical applicability of serum concentration techniques to enhance the detection of prostate-specific antigen (PSA) in men with recurrent prostate cancer after radical prostatectomy.

METHODS

We concentrated blood serum by lyophilization and ultrafiltration from female patients who had undergone cystoprostatectomy, "cured" patients who had undergone radical prostatectomy, patients without prostate cancer, and patients with prostate cancer treated with radiation or hormonal therapy. The primary study group consisted of 31 patients with recurrent disease after radical prostatectomy whose initial postoperative PSA fell to undetectable levels (less than 0.07 ng/mL) that later turned positive (0.07 ng/mL or more) by the Tosoh AIA 600 immunoassay run in the ultrasensitive mode. All serum samples of less than 0.07 ng/mL were concentrated by lyophilization or ultrafiltration.

RESULTS

Serum concentrated by lyophilization and filtration detected PSA recurrence significantly earlier than did unconcentrated serum in 29 of 31 patients (94%) and in 28 of 31 patients (90%), respectively. The mean advantage for the 29 patients was 362 days; for the 28 patients it was 383 days. The mean native PSA was 0.04 ng/mL (range 0.00 to 0.06) at the time of earliest detection by concentration techniques. Serum from female patients who had undergone cystoprostatectomy and "cured" patients who had undergone radical prostatectomy failed to concentrate, giving a test specificity of 100%.

CONCLUSIONS

Serum concentration is a specific and sensitive technique that provides a significant lead time of an additional 12 months in detecting cancer recurrence after radical prostatectomy when compared with nonconcentrated serum. Because the Tosoh assay, when run in the ultrasensitive mode, gave an additional lead time of 9 months at a residual cancer detection limit of 0.07 ng/mL, the combination of the Tosoh assay and serum concentration allows detection of a failed radical prostatectomy about 2 years earlier than does the Hybritech Tandem-R assay, which has a residual cancer detection limit of 0.2 ng/mL.

Can free and total prostate specific antigen and prostatic volume distinguish between men with negative and positive systematic ultrasound guided prostate biopsies?

PURPOSE

We evaluated the role of free and total serum prostate specific antigen (PSA) and prostate volume in discriminating between men with negative and positive transrectal ultrasound guided biopsies.

MATERIALS AND METHODS

A total of 104 consecutive men with a positive biopsy and at least 3 mm. of prostate cancer was compared to 110 consecutive men with a negative biopsy. Prostate volume was determined by transrectal ultrasound. Total PSA was determined by the Tosoh AIA-600 PSA assay and free PSA was measured by the PSA II Dianon assay. We determined the free-to-total PSA ratio, free and total PSA densities, and the relationship of free PSA and free-to-total PSA ratio to prostate volume.

RESULTS

Using a 23% cutoff value of free-to-total PSA, only 22.7% of biopsies were preventable in patients with a negative biopsy but 9.6% of the cancers were missed. At a total PSA of 4 to 10 ng./ml. 44.4% of the biopsy negative cases were correctly identified while missing 9.1% of the cancers if a 20% free PSA cutoff is used. For total PSA more than 10 ng./ml. an 18% free PSA cutoff properly identified 30.2% of the biopsy negative cases while missing 9.3% of the cancers. Percent free PSA is a better discriminant than prostate volume for total PSA more than 4 ng./ml. and the combination was not helpful. Free PSA density was identical in patients with negative and positive biopsies. There was no relationship between free PSA or free-to-total PSA ratio levels and prostate volume.

CONCLUSIONS

Use of a single discriminant criterion of free-to-total PSA ratio in the practical clinical setting of distinguishing negative and positive biopsies appears useful in patients with a total PSA of 4 to 10 ng./ml. Since free PSA is unrelated to prostate volume in biopsy negative and positive cases the physiological basis of free PSA is an enigma.

Multicenter comparison of the diagnostic performance of free prostate-specific antigen

OBJECTIVES

This study examined the multicenter clinical performance of noncomplexed (free) prostate-specific antigen (PSA) in men presenting with total PSA values between 2.5 to 20 ng/mL.

METHODS

Prebiopsy serum samples were obtained from 1,081 consecutively accrued, histologically diagnosed men between the ages of 40 and 75 years with total PSA values falling between 2.5 and 20 ng/mL. Total PSA was determined by either the Tosoh AIA-1200 or Hybritech method. Free PSA values were determined using the Dianon PSA II immunoradiometric method. Free PSA was expressed as a percentage of total PSA. Immunochemistry was performed at each accrual site.

RESULTS

Among men diagnosed with prostate cancer (CaP), only 4% (21/520) had proportions of free to total PSA values > 25%. Conversely, among men with benign prostatic disease, only 2% (13/561) had proportions of free to total PSA values < 7%. These results confirm those of previous research. Differences among sites were found in age and prostate volume.

CONCLUSIONS

These data confirm that free PSA values < 7% are highly suspicious for CaP whereas free PSA values > 25% suggest absence of malignancy. The data also suggest that age and/or prostate volume influences the serum level of free PSA but does not affect the diagnostic cutoff points of 7% and 25%. Future analysis is needed to confirm that younger men with small prostates are at higher risk for CaP.

Addition of purified prostate specific antigen to serum from female subjects: studies on the relative inhibition by alpha 2-macroglobulin and alpha 1-antichymotrypsin

PURPOSE

Two forms of prostate specific antigen (PSA), 1 complexed to alpha 1-antichymotrypsin and the other a free PSA, are recognized by current commercially available immunoassays. A third form of PSA complexed to alpha 2-macroglobulin also is present in the serum. To study these 3 different molecular forms of PSA in vivo, we simulated leakage of PSA from the prostate into the serum in vitro.

MATERIALS AND METHODS

Purified seminal fluid PSA was incubated with fresh sera from female subjects at different concentrations. Following gel filtration chromatography, the 3 forms of PSA were studied by immunoassays and Western blot analysis.

RESULTS

Using a commercial immunoassay, 60% of immunoreactivity of seminal fluid PSA was lost after incubation with sera from female subjects. Western blot analysis showed that most of this loss in PSA signal was caused by complexation to alpha 2-macroglobulin. Minimal, if any, complexation to alpha 1-antichymotrypsin occurred even when excess alpha 1-antichymotrypsin was added to the serum.

CONCLUSIONS

Our studies demonstrated that alpha 2-macroglobulin is a much stronger inhibitor to PSA than alpha 1-antichymotrypsin. Further studies of these complexes may be important. They clearly explain why spiking PSA into sera from female subjects to be used as quality controls for PSA assays leads only to the free form of enzymatically inactive PSA in the serum, and not to the dominant form of complexed PSA and alpha 1-antichymotrypsin present in human serum.

Pathological characteristics and prognosis of nonpalpable and palpable prostate cancers with a Hybritech prostate specific antigen of 4 to 10 ng./ml

PURPOSE

We compared the surgical pathological findings and postoperative course of patients with palpable and nonpalpable prostate cancers.

MATERIALS AND METHODS

All patients with untreated prostate specific antigen (PSA) 4 to 10 ng./ml. who underwent radical prostatectomy between December 1984 and December 1993 were reviewed to select 61 with clinical stage T1c (nonpalpable) with stages T2a to c (palpable) disease.

RESULTS

Nonpalpable cancers were smaller (2.99 versus 4.42 cc for palpable tumors), had smaller volumes of Gleason grade 4 to 5 cancer (0.66 versus 1.32 cc, respectively) and were less likely to have positive surgical margins (13 versus 22%, respectively) or significant (1 cm. or more) capsular penetration (10 versus 26%, respectively). Nonpalpable and palpable cancers had similar rates of seminal vesicle invasion (3.3 versus 4.3%, respectively) and positive lymph nodes (1.6 versus 0%, respectively). More than 90% of patients with nonpalpable cancer were biochemically cancer-free postoperatively, and the remainder were alive with disease after a mean followup of 25.1 months, compared to 69% disease-fee, 28% alive with disease and 2.5% dead of prostate cancer after mean followup of 43.8 months among those with palpable disease.

CONCLUSIONS

We conclude that nonpalpable prostate cancers are pathologically more favorable than palpable prostate cancers with PSA 4 to 10 ng./ml. Our preliminary results also indicate that nonpalpable cancers are less likely to recur postoperatively than palpable cancers with a similar PSA range.

A comparison of the free fraction of serum prostate specific antigen in men with benign and cancerous prostates: the best case scenario

PURPOSE

In most previous studies of free-to-total serum prostate specific antigen (PSA) ratios, the specimens from patients with prostate cancer or those with benign prostatic hyperplasia (BPH) have not been highly characterized. We compared preoperative sera from post-radical prostatectomy patients with clinically significant cancers of at least 2 cm.3 to sera from those with BPH and large, biopsy negative prostates.

MATERIALS AND METHODS

We used 2 different time resolved immunofluorometric assays for free and total PSA, and a combination of a chemoluminescent immunoassay for free PSA detection with an immunoradiometric assay for total PSA to measure free and total PSA. The serum ratios of free-to-total PSA in these assays were compared to those obtained previously from gel filtration studies. Sera from 51 men with prostate cancer volumes of 2 to 18 cm.3 were compared to those from 48 men with BPH and a mean prostate volume of 78 +/- 7 cm.3. The respective mean serum PSA levels plus or minus standard deviation were 10.0 +/- 6.3 and 8.9 +/- 7.2 ng./ml.

RESULTS

Monoclonal assays for free PSA confirmed the previous study with gel filtration. For PSA 4 to 10 ng./ml., 94 to 95% of the men with prostate cancer were correctly diagnosed, with a cutoff of less than 15% for free-to-total PSA on immunofluorometric assay and less than 14% for chemoluminescent immunoassay with immunoradiometric assay. However, 46% (immunofluorometric assay) and 36% (chemoluminescent immunoassay and immunoradiometric assay) of men with BPH did not have enough free PSA for diagnosis of BPH (that is 36 to 46% false-positive rate).

CONCLUSIONS

For total PSA 4 to 10 ng./ml., the sensitivity of approximately 15% free-to-total PSA for prostate cancer is high (94 to 95%) but 36 to 46% of men with BPH and a large gland will not be correctly identified. For PSA 2 to 4 ng./ml., no ratio of percent free-to-total PSA discriminated BPH from prostate cancer.