Preoperative serum prostate specific antigen levels between 2 and 22 ng./ml. correlate poorly with post-radical prostatectomy cancer morphology: prostate specific antigen cure rates appear constant between 2 and 9 ng./ml.

PURPOSE: Serum prostate specific antigen (PSA) is widely used as a guide to initiate prostatic biopsies and to follow men older than 50 years old with and without prostate cancer. However, benign prostatic hyperplasia (BPH) is a common cause of serum PSA values between 2 and 10 ng./ml. A better understanding of the relationships among serum PSA, prostate cancer and BPH is important. MATERIALS AND METHODS: A total of 875 men underwent radical prostatectomy at our institution between December 1984 and January 1997. Of these men 784 had a serum PSA of 2 to 22 ng./ml., including 579 with the largest cancer located in the peripheral zone of the prostate. Of the 579 men 406 had serum PSA followups for greater than 3 years after radical prostatectomy. We examined Pearson correlations (R2) between preoperative serum PSA, and the volume of Gleason grades 4/5 and 3 to 1 cancer in 784 men, separating peripheral zone from transition zone cancers. We used broken line regression with break points of 7 and 9 ng./ml. preoperative PSA to summarize the relationship of each PSA doubling to 5 different morphological variables in 579 men with peripheral zone cancer. A 9 ng./ml. break point was used for prostate weight. Trend summaries with a local regression line for the relationships between 6 morphological variables and PSA were superimposed on full scatterplots of the 579 men with PSA less than 22 ng./ml. Cox proportional hazard models were used to examine 5-year PSA failure-free probabilities based on 406 men with minimal PSA followups greater than 3 years at break points of 7 to 9 ng./ml. PSA. RESULTS: Pearson correlation between cancer volume and preoperative serum PSA in 875 men was weak (r2 = 0.27) and driven by large cancers with serum PSA greater than 22 ng./ml. For peripheral zone cancer the overall R2 x 100 for 641 men with low and high grade cancer was 10% and only 3% for low grade cancer, that is almost no PSA produced by these peripheral zone cancers enters the serum. All morphological variables changed at rates of doubtful medical significance below a PSA of 7 to 9 ng./ml. but at rates that were significantly worse above 9 ng./ml. R2 for these relationships was never greater than 15%. Large individual morphological variations at all levels of PSA emphasize the serious limitation of PSA as a predictor of prostate cancer morphology. Below 9 ng./ml. prostate weight increased by 21% for each doubling of PSA but above 9 ng./ml. the increase was only 4.8%. CONCLUSIONS: Preoperative serum PSA has a clinically useless relationship with cancer volume and grade in radical prostatectomy specimens, and a limited relationship with PSA cure rates at preoperative serum PSA levels of 2 to 9 ng./ml. Trend summaries for prostate weight on broken line regression showed that below 9 ng./ml. BPH is a strong contender for the cause of PSA elevation, constituting the primary cause of the over diagnosis of prostate cancer.     

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 plus/minus 7 cm.³. The respective mean serum PSA levels plus or minus standard deviation were 10.0 plus/minus 6.3 and 8.9 plus/minus 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 percent of the men with prostate cancer were correctly diagnosed, with a cutoff of less than 15 percent for free-to-total PSA on immunofluorometric assay and less than 14 percent for chemoluminescent immunoassay with immunoradiometric assay. However, 46 percent (immunofluorometric assay) and 36 percent (chemoluminescent immunoassay and immunoradiometric assay) of men with BPH did not have enough free PSA for diagnosis of BPH (that is 36 to 46 percent false-positive rate).

Conclusions

For total PSA 4 to 10 ng./ml., the sensitivity of approximately 15 percent free-to-total PSA for prostate cancer is high (94 to 95 percent) but 36 to 46 percent 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.     

THE EFFECT OF HIGH GRADE PROSTATIC INTRAEPITHELIAL NEOPLASIA ON SERUM TOTAL AND PERCENTAGE OF FREE PROSTATE SPECIFIC ANTIGEN LEVELS

PURPOSE: It is established that the percentage of free prostate specific antigen (PSA) in serum is low in patients with prostate cancer. An unanswered question is whether a low percentage of free PSA can be explained by high grade prostatic intraepithelial neoplasia alone. We compared the percentage of free PSA in men with high grade prostatic intraepithelial neoplasia alone, prostate cancer, benign prostatic hyperplasia (BPH) and a normal prostate (that is normal digital rectal examination and PSA less than or equal to 2.5 ng./ml.). MATERIALS AND METHODS: From October 1994 through December 1997, 48 men were diagnosed with high grade prostatic intraepithelial neoplasia without concomitant prostate cancer. Of these men 43 with a mean age plus or minus standard deviation of 67.4 +/- 7.8 years comprised our study group. To date none has been diagnosed with cancer during followup. Serum free and total PSA levels were measured, and the percentage of free PSA was calculated. The percentage of free PSA in the 43 men was compared to that in 50 with prostate cancer (mean age 65.4 +/- 7.8 years), 50 with biopsy proved BPH (67 +/- 7) and 43 with a normal prostate (61 +/- 8). RESULTS: There was no significant difference in mean total serum PSA in patients with high grade prostatic intraepithelial neoplasia, prostate cancer or BPH. The percentage of free PSA was significantly lower in patients with prostate cancer (14.9 +/- 6.5%) than those with high grade prostatic intraepithelial neoplasia (20.8 +/- 7.1%), BPH (20.1 +/- 7.3%) or a normal prostate (27.7 +/- 12.2%). There was also no significant difference in the percentage of free PSA between men with high grade prostatic intraepithelial neoplasia (20.8 +/- 7.1%) and those with BPH (20.1 +/- 7.3%). Additionally, men with a normal prostate had a higher percentage of free PSA (27.7%) than those with BPH (20.1%), high grade prostatic intraepithelial neoplasia (20.8%) or prostate cancer (14.9%). CONCLUSIONS: The percentages of free PSA in men with high grade prostatic intraepithelial neoplasia and BPH are similar, and significantly higher than those found in men with prostate cancer.     

Prostate Specific Antigen Density of the Transition Zone: A New Effective Parameter for Prostate Cancer Prediction

Purpose

Use of prostate specific antigen (PSA) density to enhance the predictive value of detecting prostate cancer at intermediate PSA levels has been limited due to contradictory results in large scale studies. Most PSA leakage from the benign prostate into the serum comes from the transition zone. Therefore, in patients with benign prostatic hyperplasia (BPH) and prostate cancer with a serum PSA of less than 10 ng./ml. we studied and compared the values of PSA density of the total prostate and the transition zone. We examined the ability of PSA density of the transition zone to enhance prostate cancer detection in patients with intermediate PSA levels.

Materials and Methods

The volumes of the entire prostate and of the transition zone were determined by transrectal ultrasound. PSA density for both regions was calculated in 88 patients with histologically confirmed prostate cancer (radical prostatectomy), and 74 with BPH and histologically proved benign disease.

Results

Average total prostate PSA density plus or minus standard deviation was 0.12 +/− 0.07 and 0.22 +/− 0.12 ng./ml./cc in patients with BPH and prostate cancer, respectively, while average PSA density of the transition zone was 0.21 +/− 0.13 and 1.02 +/− 0.70 ng./ml./cc, respectively (p <0.0001). If a total prostate PSA density of 0.15 had been chosen, the cancer would have been missed in 34% of the patients compared to 10% if a cutoff value of 0.35 for PSA density of the transition zone had been chosen (p <0.001). Overall, in patients with a PSA of 0.25 to 10.0 ng./ml. the sensitivity and specificity of PSA density of the transition zone for predicting prostate cancer at a 0.35 cutoff value were 90 and 93%, respectively, compared to 94 and 89%, respectively, for those with a PSA of 4 to 10 ng./ml.

Conclusions

In our study PSA density of the transition zone was much more accurate in predicting prostate cancer than was total prostate PSA density for PSA levels of less than 10 ng./ml. With respect to the high sensitivity and specificity, if confirmed in large prospective studies, including patients seen for early diagnosis, PSA density of the transition zone could become a routine tool for urologists in the prediction of prostate cancer in men with a PSA of 4 to 10 ng./ml.     

Predicting radionuclide bone scan findings in patients with newly diagnosed, untreated prostate cancer: prostate specific antigen is superior to all other clinical parameters.

Presently, the standard staging evaluation of prostate cancer includes digital rectal examination, measurement of serum tumor markers and a radionuclide bone scan. To evaluate the ability of local clinical stage, tumor grade, serum acid phosphatase, serum prostatic acid phosphatase (PAP) and serum prostate specific antigen (PSA) to predict bone scan findings, a retrospective review of 521 randomly chosen patients (mean age 70 years, range 44 to 92 years) with newly diagnosed, untreated prostate cancer was performed. Local clinical stage, tumor grade, acid phosphatase, PAP and PSA all correlated positively with bone scan findings (p less than 0.0001). Using receiver operating characteristic curves, however, PSA had the best over-all correlation with bone scan results. The median serum PSA concentration in patients with a positive bone scan was 158.0 ng./ml., whereas men with a negative bone scan had a median serum PSA level of 11.3 ng./ml. (p less than 0.0001). Using multivariate logistic regression analysis, local clinical stage, tumor grade, acid phosphatase and PAP were evaluated in combination with PSA to assess whether these parameters increased the ability of PSA alone to predict bone scan findings. None of these clinical parameters, irrespective of the combination used, contributed appreciably to the predictive power of PSA alone. A probability plot with 95% confidence intervals was constructed that allows the practicing urologist to estimate on an individual basis the probability of a positive bone scan for any given serum PSA value. The most significant finding of this study, however, was the negative predictive value of a low serum PSA concentration for bone scan findings. In 306 men with a serum PSA level of 20 ng./ml. or less only 1 (PSA 18.2 ng./ml.) had a positive bone scan (negative predictive value 99.7%). This finding would suggest that a staging radionuclide bone scan in a previously untreated prostate cancer patient with a low serum PSA concentration may not be necessary.     

Hormonal predictors of prostate cancer

INTRODUCTION: Androgens are necessary for the development and functioning of the prostate gland. The association of serum testosterone and pituitary hormone levels with prostate cancer development is not completely understood. In this clinical study, we evaluated the role of serum testosterone, free testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels in predicting prostate cancer risk in patients who had transrectal ultrasonography-guided prostate biopsy with the suspicion of prostate cancer. MATERIAL AND METHODS: A total of 211 patients who were selected to undergo prostatic biopsy due to abnormal digital rectal examination and/or a serum prostate-specific antigen (PSA) level >2.5 ng/ml were included in the study. The patient characteristics of total PSA, free/total PSA ratio, serum total testosterone, free testosterone, free/total testosterone ratio, FSH and LH levels were compared according to the pathological diagnosis. RESULTS: The mean age was 63.91 years (range 44-83) and the mean PSA level was 9.23 ng/ml (range 0.13-50.41) in the whole group. Of 211 patients, 69 (32.7%) were positive for prostate cancer. The patients who were positive for prostate cancer had statistically lower levels of serum total testosterone compared with the patients who were diagnosed as having benign prostatic hyperplasia (BPH; 405 vs. 450.5 ng/dl, respectively; p = 0.013). The serum FSH level was significantly higher in men with prostatic cancer than in men with BPH (7.56 vs. 6.06 mIU/ml, respectively; p = 0.029). No significant differences between men with prostatic cancer and those with BPH were found for serum LH levels. When normal ranges for serum free and total testosterone levels were defined as 9 pg/ml and 300 ng/dl, respectively, patients who had low free testosterone and total testosterone levels had significantly higher cancer detection rates than patients with high serum androgen levels: 40.8% (40/98) versus 25.6% (29/113) (p = 0.021), and 48.6% (18/37) versus 29.3% (51/174), respectively (p = 0.023). After logistic regression analysis, none of the hormones showed a significant difference in predicting the risk of prostate cancer in patients undergoing prostate biopsy with suspicion of the disease. CONCLUSION: Our data suggest that patients diagnosed with prostate cancer have low levels of serum testosterone and high levels of serum FSH compared with the patients with BPH. No support was found for the theory that high levels of testosterone increase prostate cancer risk. Further studies are needed to clarify the relationship between hormones and prostate cancer etiology.     

Value of prostate-specific antigen measurements with newly developed enzyme immunoassay (MARKIT-M PA)]

Serum prostate-specific antigen (PSA) levels in patients with prostate cancer and benign prostate hypertrophy (BPH) were investigated with a newly developed enzyme immunoassay (MARKIT-M PA, Dainippon Pharmaceutical Co. Ltd., Osaka, Japan). Sensitivity of the assay system is 0.5 ng/ml and the detection range is 0.5-100 ng/ml. There was a high linear correlation (r = 0.987) between the assay and MARKIT-F PA, and values obtained with the assay were almost equal to those yielded by MARKIT-F PA assay. Using the BPH group as a negative control, the upper cut-off value in BPH patients was determined to be 3.6 ng/ml. Of the 48 patients with untreated prostate cancer, 77% was detectable by means of MARKIT-M PA assay. Using the BPH group as a negative control, specificity and efficiency were 93% and 86%, respectively. In another group of 27 BPH patients whose blood samples were taken immediately after digital prostatic examination, PSA was elevated in 15%. During follow-up of prostate cancer patients, PSA was elevated in 82% at the time of clinically detectable progression. In 15 patients whose disease was clinically well controlled, all levels of PSA were observed to be negative. These findings suggests that detection of serum PSA with this assay is of great use both in the diagnosis and monitoring of prostate cancer patients.     

Discrimination of men with prostate cancer from those with benign disease by measurements of human glandular kallikrein 2 (HK2) in serum

PURPOSE: To investigate the clinical value of measuring human glandular kallikrein 2 (hK2) compared with free and total prostate specific antigen (PSA-F and PSA-T) in serum from patients with prostate disease. MATERIALS AND METHODS: Serum from healthy controls, from men with benign prostate hyperplasia (BPH), clinically localized prostate cancer (PCa), and advanced PCa were analyzed for hK2 (using an in-house-research assay with detection limit of 0.05 ng./mL and <0.1% cross-reaction with PSA) and for PSA-F and PSA-T (using the Dual Prostatus assay from EG&G Wallac). RESULTS: HK2 concentrations were <0.05 ng./mL in 50/50 healthy volunteers but significantly higher (p <0.0001) and > or =0.05 ng./mL in 28/54 (52%) patients with BPH. In comparison to these men, the hK2 levels were significantly higher (p <0.0001, median 0.085 ng./mL) and > or =0.05 ng./mL in 100/136 (74%) men with clinically localized PCa. Compared with localized PCa, the hK2 levels were significantly higher (p <0.0001, median 0.57 ng./mL) and > or =0.05 ng./mL in 55/57 (96%) patients with advanced PCa. The median hK2 levels ranged from 1.3 to 1.6% of those of PSA-T in all three patient groups, whereas percent hK2/PSA-F and hK2 x PSA-T/PSA-F levels were significantly higher in cancer patients compared with those with BPH. In the discrimination of clinically localized PCa from BPH, hK2 x PSA-T/PSA-F gave the largest area under the receiver operating curve (AUC = 0.81) and significantly (p = 0.025) larger AUC than PSA-T alone (0.70). Further, at 95% sensitivity there was significant gain in specificity, and at specificity levels of 90 to 95% there was significant gain in sensitivity using the measurements of PSA-T+PSA-F+hK2 compared with analysis of PSA-T and/or percent free PSA. CONCLUSIONS: Discrimination of patients with benign prostate disease from those with prostate cancer was significantly enhanced using measurements of hK2 in addition to those of PSA-T and PSA-F. Percent hK2/PSA-F was higher in PCa than in BPH, a phenomena not yet understood.     

The effect of digital rectal examination on the serum prostate specific antigen concentration: results of a randomized study.

To determine the effect of digital rectal examination on the serum prostate specific antigen (PSA) concentration a prospective, randomized, controlled trial involving 143 patients was conducted. Of the patients 86 (60%) had benign prostatic hyperplasia (BPH), 47 (33%) had prostate cancer and 10 (7%) had chronic prostatitis. The study group consisted of 71 men, all of whom had a serum PSA determination followed by a digital rectal examination and then a second serum PSA determination. The control cohort consisted of 72 men, all of whom had 2 serum PSA determinations without an intervening digital rectal examination. The median change in the serum PSA level for the study group was 0.4 ng./ml. compared to -0.1 ng./ml. for the control cohort (p less than 0.0001). For 76% of the study patients the second serum PSA level was greater than the initial value; only 32% of the control patients exhibited a higher second serum PSA level than the initial level (p less than 0.0001). However, only 4 patients with an initial PSA value in the reference range (0.0 to 4.0 ng./ml.) had a post-digital rectal examination value greater than 4.0 ng./ml. and only 1 patient whose presenting serum value was less than 10.0 ng./ml. had a serum PSA level greater than this cutoff point after digital rectal examination. This minimal change in serum PSA after digital rectal examination was independent of the diagnosis (BPH, cancer or chronic prostatitis), initial serum PSA concentration and examiner. Thus, although digital rectal examination had a statistically significant effect on the serum PSA concentration, the clinical significance of a 0.4 ng./ml. median increase appears inconsequential. Based on these findings, physicians should be confident that the serum PSA concentration in the immediate post-digital rectal examination period is accurate and does not compromise clinical use of the tumor marker.     

STABILITY OF FREE AND TOTAL PROSTATE SPECIFIC ANTIGEN IN SERUM FROM PATIENTS WITH PROSTATE CARCINOMA AND BENIGN HYPERPLASIA

Purpose

Instability of prostate specific antigen (PSA) in serum might complicate the interpretation of the free-to-total PSA ratio. We studied the in vitro stability of free PSA and total PSA in serum of patients with prostate cancer or benign prostate hyperplasia (BPH), and of elderly man without known prostate disease. Furthermore, we investigated conditions to stabilize the in vitro values in serum.

Materials and Methods

The effects of storage at 4C on free and total PSA were investigated in serum of 32 men with prostate cancer, 25 with BPH and 29 older than 70 years. All had total PSA less than 25 micro g./l. The influence of total PSA levels on in vitro changes in free-total PSA was studied in serum of 39 other prostate cancer patients (total PSA 1.7 to 298 micro g./l.). Stabilization studies were performed in yet another series of samples from 54 prostate cancer patients (total PSA 1.3 to 238 micro g./l.) by adjustment of serum pH to 5.5 before storage. Free and total PSA was measured by a commercial immunofluorometric assay, as well as by in-house immunofluorometric assays. Statistical analyses of the results were performed by analysis of variance with repeated measures.

Results

We found no difference between the results obtained by the 2 assay systems. After 7 days at 4C there was a slight decrease in total PSA in sera of prostate cancer patients, BPH patients and men older than 70 years. A decrease in mean free PSA values occurred in all groups (21.3, 15.7 and 14.6%, respectively). The decrease of free PSA with time was significant (p <0.0001) in all groups but there was no significant difference among the groups (p = 0.16). The concomitant decrease in free-to-total PSA ratio was significant in all groups (p <0.0001). This change was group dependent (p = 0.003), with the largest decrease in the prostate cancer group. Large interindividual differences were observed. Storage at 4C for 7 days of sera of 39 patients with localized and disseminated prostate cancer (total PSA 1.7 to 298 micro g./l.) gave a more pronounced decrease in free PSA than in total PSA. Adjustment of serum pH to 5.5 had a stabilizing effect on free PSA and on the free-to-total PSA ratio, giving a significantly smaller change in both values (p <0.0001).

Conclusions

In vitro instability of free PSA in serum and large interindividual differences should be considered when using the ratio of free-to-total PSA in evaluation of patients with suspected prostate cancer. Serum samples should be stored frozen if not analyzed immediately or acidified to pH 5.5. Interpretation of data from determination of free-to-total PSA ratio should be done with caution if the sampling and storage conditions are not known.     

RATIO OF FREE-TO-TOTAL PROSTATE SPECIFIC ANTIGEN IN SERUM CANNOT DISTINGUISH PATIENTS WITH PROSTATE CANCER FROM THOSE WITH CHRONIC INFLAMMATION OF THE PROSTATE

Purpose

We demonstrate the effect of chronic inflammation of the prostate on the ratio of free-to-total prostate specific antigen (PSA) in serum calculated as a percentage of free PSA and, therefore, that percentage of free PSA is an unspecific means to distinguish among prostate cancer, chronic prostatitis and benign prostatic hyperplasia (BPH).

Materials and Methods

Total, free and percentage of free PSA was measured in 66 men with prostate cancer, 119 with BPH and 17 with asymptomatic chronic prostatitis. In all patients the diagnosis was histopathologically confirmed by microscopic examination of prostatic specimens after sextant biopsy, transurethral prostatic resection or prostatectomy.

Results

The median values of total, free and percentage of free PSA were 4.11 micro g./l., 0.75 micro g./l. and 20.4% in patients with BPH, 10.0 micro g./l., 0.84 micro g./l. and 8.5% in those with prostate cancer, and 7.60 micro g./l., 1.23 micro g./l. and 10.6% in those with chronic prostatitis. Patients with prostate cancer and chronic prostatitis had a significantly lower percentage of free PSA than those with BPH. Receiver operating characteristics curve analysis showed that percentage of free PSA as a discriminator between prostate cancer and BPH was not suitable for differentiating between prostate cancer and chronic prostatitis.

Conclusions

Chronic prostatitis is not characterized by elevated total PSA concentrations alone but also by a decreased percentage of free PSA, a tendency similar to that in prostate cancer. This unspecific change in percentage of free PSA must be considered to interpret the percentage of free PSA correctly.     

The accuracy of the increased prostate specific antigen level (greater than or equal to 20 ng./ml.) in predicting prostate cancer: is biopsy always required?

PURPOSE: Urologists are often referred patients who initially present with an extremely high serum prostate specific antigen (PSA) level. Despite a presumptive diagnosis of prostate cancer, many of these men undergo biopsy to obtain a tissue diagnosis before treatment with androgen ablative therapy. We examined a data base of men undergoing prostate biopsy to determine the accuracy of high PSA levels (greater than or equal to 20 ng./ml.) in predicting prostate cancer. MATERIALS AND METHODS: We reviewed the records of 1,250 consecutive patients undergoing transrectal ultrasound guided prostate biopsy at 1 institution. From this data base we identified all patients with PSA greater than or equal to 20 ng./ml. at the time of prostate biopsy. The accuracy of PSA in predicting cancer was determined by calculating positive predictive values for PSA ranges and PSA cutoffs. RESULTS: We identified 187 men (15%) presenting with PSA greater than or equal to 20 ng./ml. Of these 187 men 157 (84.0%) were diagnosed with prostate cancer on initial biopsy. Due to a negative initial biopsy, yet a high suspicion of cancer, 12 (6.4%) patients underwent at least 1 repeat biopsy. Of these 12 men 6 (50%) were diagnosed with cancer on repeat biopsy. Overall, 163 of the 187 men (87.2%) were diagnosed with prostate cancer by biopsy. Stratified by PSA ranges, positive predictive values were 73.6% for 20 to 29.9, 90.3% for 30 to 39.9, 93.8% for 40 to 49.9, 100% for 50 to 99.9, 95% for 100 to 199.9 and 100% for greater than or equal to 200 ng./ml. Using PSA cutoffs positive predictive values were 95.7% for PSA greater than or equal to 30, 97.6% for PSA greater than or equal to 40 and 98.5% for PSA greater than or equal to 50 ng./ml. CONCLUSIONS: Serum PSA, when increased above 50 ng./ml., is 98.5% accurate in predicting the presence of prostate cancer on tissue biopsy. Nonetheless, since transrectal prostate biopsy has a low complication rate and is relatively well tolerated, we recommend continuing to biopsy most patients with high PSA levels. However, carefully selected elderly patients on chronic anticoagulation, with severe co-morbidities or presenting with spinal cord compression may not require biopsy before androgen ablative therapy since PSA is highly accurate in diagnosing prostate cancer at levels greater than 50 ng./ml.     

Prostate specific antigen density for discriminating prostate cancer from benign prostatic hyperplasia in the gray zone of prostate-specific antigen.

Serum prostate specific antigen (PSA) is currently the best blood marker for prostate cancer. However, low specificity for detection of prostate cancer, especially in the gray zone of PSA, is a problem. We evaluated the clinical significance of PSA density (PSAD) in gray zone PSA cases with conversion of serum PSA to a Stanford reference value. In a series of histologically confirmed 63 benign prostatic hyperplasia (BPH) patients and 234 prostate cancer patients, 36 BPH patients and 25 prostate cancer patients had gray zone PSA levels. Serum PSA was measured with the Markit-F or Markit-M PA assay. All data were converted to Stanford reference values. We used transabdominal ultrasound to determine prostate volume. PSAD was determined as the serum PSA/prostate volume ratio. The mean PSA values for BPH and prostate cancer were 6.42 +/- 1.80 and 7.80 +/- 2.15 ng/ml (p = 0.0116), respectively, and prostate volume was 33.4 +/- 14.1 ml and 17.1 +/- 8.2 ml, respectively (p < 0.0001). The mean PSAD for prostate cancer was 0.572 +/- 0.363 while that for BPH was 0.218 +/- 0.085 (p = 0.0001). Cut-off values with sensitivity > 90% were 0.218 for PSAD and 30 ml for prostate volume. At these cut-off values, specificity reached 56% for each marker. In discriminating prostate cancer from BPH in the gray zone of PSA, PSAD demonstrated better performance than PSA.     

Prostate specific antigen in hormonally treated stage D2 prostate cancer: is it always an accurate indicator of disease status?

The clinical significance of serum prostate specific antigen (PSA) values in hormonally treated prostate cancer patients and the effect of hormonal therapy on the serum PSA concentration, independent of the response observed from its antitumor activity, are not well defined. To elucidate further the influence of antiandrogen therapy on serum PSA expression, 81 randomly selected patients with stage D2 prostate cancer were evaluated with respect to serum PSA concentration. These patients were divided into 2 groups on the basis of previous hormonal therapy. Group 1 consisted of 43 patients 55 to 89 years old (mean age 71 years) who had received no prior therapy for prostate cancer. Group 2 included 38 men 58 to 84 years old (mean age 72 years) who had received only androgen deprivation therapy with either bilateral orchiectomy or diethylstilbestrol. The mean interval between initiation of antiandrogen therapy and evaluation of these patients was 14 months (range 8 to 31 months). At the time of PSA determination both groups were similar in all respects, including tumor grade, disease symptoms and bone scan findings. The median serum PSA concentration was 96.0 ng./ml. in group 1 and 16.5 ng./ml. in group 2 (p less than 0.001), despite both groups having similar symptoms and widespread metastatic disease on radionuclide bone scan. In group 1 only 1 patient (2%) had a serum PSA level less than 4.0 ng./ml., whereas 13 men (34%) in group 2 had a serum PSA concentration below 4.0 ng./ml. (p less than 0.001). Of the patients in group 1, 2% and of the men in group 2, 45% had a serum PSA concentration less than 10 ng./ml. (p less than 0.001). These findings demonstrate that the serum PSA level in prostate cancer patients treated hormonally may have a significantly different meaning than the same serum PSA value in patients without hormonal therapy. In addition, these observations suggest that PSA expression may be under hormonal regulation and that androgen deprivation therapy may have a direct effect on the serum PSA concentration, independent of the response obtained from any antitumor activity. However, the exact mechanism of this androgenic influence on PSA expression awaits further investigation at the cellular level.     

Serum prostate specific antigen is a strong predictor of future prostate growth in men with benign prostatic hyperplasia. PROSCAR long-term efficacy and safety study

PURPOSE: We analyze patterns of prostate growth in men diagnosed with benign prostatic hyperplasia (BPH) and treated with placebo during 4 years, and determine which baseline parameters were the strongest predictors of growth. MATERIALS AND METHODS: A total of 3,040 men were enrolled in the 4-year randomized, placebo controlled Proscar Long-Term Efficacy and Safety study. Of these men a subgroup of 10% underwent pelvic magnetic resonance imaging prostate volume measurement at baseline and yearly thereafter. Absolute and percent volume changes during 4 years were calculated in the 164 placebo treated men in the subgroup. The ability of age, baseline prostate volume and prostate specific antigen (PSA) to predict prostate growth in placebo treated patients was assessed by multiple linear regression analyses, receiver operator characteristics curves, and evaluations of growth stratified by tertiles of baseline serum PSA and decades of life. RESULTS: In placebo treated patients a steady increase in mean plus or minus standard deviation prostate volume from year to year was noted (2.5+/-6.1, 4.9+/-6.8, 6.4+/-8.5 and 7.2+/-8.8 ml. at years 1, 2, 3 and 4, respectively). Mean volume changes at 4 years ranged from -9 to +30 ml. Mean percent change from baseline ranged from 12.5% to 16.6% for men 50 to 59 years old to those 70 to 79 years old. Baseline serum PSA was a strong predictor of growth with 7.4% to 22.0% change at 4 years from the lowest to highest PSA tertiles. Annualized growth rates from baseline were 0.7 ml. per year for PSA 0.2 to 1.3, 2.1 for PSA 1.4 to 3.2 and 3.3 for PSA 3.3 to 9.9 ng./ml. Multiple linear regression analysis showed that serum PSA was a stronger predictor of prostate growth than age or baseline prostate volume. All but 1 man with baseline serum PSA greater than 2.0 ng./ml. had prostate growth during 4 years, and 32.6% of men with serum PSA less than 2.0 exhibited a decrease in volume. CONCLUSIONS: Serum PSA is a stronger predictor of growth of the prostate in placebo treated patients than age or baseline prostate volume. Since prostate volume is a risk factor for acute urinary retention and the need for BPH related surgery, the ability of PSA to predict prostate growth may be an important factor when considering individual treatment options for BPH. Such use of PSA represents a shift in paradigm away from focusing solely on symptoms of BPH toward a more comprehensive approach with consideration of predicting and preventing risk factors of BPH related outcomes.     

Prostate specific antigen in patients with clinical stage C prostate cancer: relation to lymph node status and grade.

The preoperatively drawn sera from 84 previously untreated patients who had clinical stage C prostate cancer and underwent staging pelvic lymph node dissections were sent for monoclonal Hybritech analysis to assess the usefulness of prostate specific antigen (PSA) in predicting lymph node status. Of the 84 patients 47 (56%) had positive lymph nodes at surgery. The median PSA value for all patients with nodal metastases was 11.4 ng/.ml., and for those without it was 11.2 ng./ml. Relative to Gleason score, median PSA values were 11.35 for 2-4, 12.2 for 5-7 and 10.9 ng./ml. for 8-10. Within each M.D. Anderson grade median PSA values were 10.15 for grade I, 13.2 for grade II, 12.7 for grade III and 10.5 ng./ml. for grade IV. Simultaneously drawn preoperative frozen serum samples for 28 of these patients were independently analyzed by the Yang radioimmunoassay. Comparing Hybritech and Yang methods revealed strong statistical co-association (correlation coefficient R2 = 97.36, p less than 0.00001) but neither assay was statistically associated with nodal metastasis. Although no PSA level excluded the presence of nodal disease, we suggest that a Hybritech PSA of greater than 30 ng./ml. and a Yang PSA of greater than 50 ng./ml. may serve as a weak adjunctive marker predicting nodal metastasis.     

Discrimination of benign from malignant prostatic disease by selective measurements of single chain,intact free prostate specific antigen

PURPOSE: Free prostate specific antigen (PSA) in serum consists of heterogeneous molecular subforms. Recently we developed an immunoassay for selective measurement of a subfraction of free PSA called intact PSA, which has been shown to be closely associated with prostate cancer. We assessed the ability of serum intact PSA to discriminate between benign and malignant prostatic disease. MATERIALS AND METHODS: In serum of 178 men with benign disease and 255 men with prostate cancer we measured total PSA and free PSA using a commercially available immunoassay. Intact PSA levels were analyzed by a newly developed assay specific for noncleaved, that is single chain forms of free PSA. Internally cleaved "nicked" PSA was calculated by subtracting intact from free PSA. We also calculated ratios of intact PSA-to-free PSA (intact-to-free PSA) and nicked PSA-to-total PSA (nicked-to-total PSA). We compared means, medians and ranges of all analytes and ratios in patients with and without cancer for the entire total PSA range and in a subset with total PSA ranging from 2 to 10 ng./ml. Furthermore, various combinations of PSA forms were tested for their predictive ability. For statistical comparison we used the Mann-Whitney U test and ROC analysis. RESULTS: The ratio intact-to-free PSA was significantly higher in cancer (median 48.5%) compared to noncancer cases (median 41.8%, p <0.0001). Conversely, the ratio nicked-to-total PSA was significantly higher in men without compared to those with prostate cancer (median 11.0% and 6.0%, respectively, p <0.0001). Highest discriminative ability was observed for a combination of intact, total and free PSA (log [intact, free, total], AUC = 0.773) followed by nicked-to-total PSA (AUC 0.755). In the subgroup of patients with total PSA levels from 2 to 10 ng./ml. only the AUC of log intact, free, total (AUC 0.706, p = 0.0017) and nicked-to-total PSA (AUC 0.704,p = 0.0019) were significantly larger compared to the AUC of total PSA (AUC 0.602). CONCLUSIONS: By contrast to measuring crude free PSA concentration, selective determination of specific free PSA subforms, intact PSA and nicked PSA proved to be useful to discriminate men with benign from malignant prostatic disease. These markers may serve to generate specific serum profiles of PSA for improved specificity and early detection of prostate cancer. To translate the encouraging statistical advantage shown in this study into a clinically applicable tool warrants further investigation.     

Systematic prostatic biopsies in 100 men with no suspicion of cancer on digital rectal examination.

A total of 100 men with a mean age of 63 years underwent, in the following order, prostate specific antigen (PSA) assay (radioimmunometric assay, normal less than 2.5 ng./ml.), rectal examination, transrectal ultrasonography with a 7 MHz. probe, measurement of the prostatic volume, and 6 ultrasound-guided randomized biopsies and biopsies of any hypoechogenic zones. All men with a suspicious prostate on rectal examination (nodule, induration or firm zone) were excluded from the study. There were 14 prostatic cancers detected: 3 (8.5%) in men less than 60 years old, 4 (11%) in men between 60 and 70 years old and 7 (24%) in men more than 70 years old. No cancer was detected in men with a PSA level of less than 10 ng./ml., 5 (26%) were detected in 19 men with a PSA level of 10 to 19 ng./ml., 4 (40%) were detected in 10 men with a PSA of 20 to 29.9 ng./ml. and 5 (100%) were detected in 5 men with a PSA of 30 or more ng./ml. A total of 66 men (66%) had a PSA level of less than 10 ng./ml. There were 18 (18%) hypoechogenic zones detected: 2 (11%) were positive for cancer but, over-all, the hypoechogenic zones revealed cancer in only 2 of 100 cases (2%). In 12 of the 14 cancers detected (86%) with no clinical suspicion the PSA level was higher than the maximal PSA level related to the prostate weight. We conclude that systematic randomized prostatic biopsies are the best method of early diagnosis, detecting 41% of all prostatic cancers in men with a normal rectal examination when the PSA level is 10 ng./ml. or more. The real question is to determine whether this early diagnosis is useful for the patient, since presently, there is no certainty of the therapeutic benefit in terms of quantity and quality of life.     

Digital rectal examination for detecting prostate cancer at prostate specific antigen levels of 4 ng./ml. or less

PURPOSE: We evaluated the detection rate of prostate cancer in men with suspicious digital rectal examination findings and serum prostate specific antigen (PSA) 4 ng./ml. or less. We also evaluated the stage and grade of cancers detected. MATERIALS AND METHODS: We screened 22,513 community volunteers by PSA testing and digital rectal examination at 6-month intervals. Biopsy was recommended when either test was suspicious for cancer. In the subset of 2,703 white and black men in whom PSA was 4 ng./ml. or less and digital rectal examination was suspicious for prostate cancer we compared compliance with biopsy recommendations, cancer detection rates, and stage and grade of cancers detected. We then correlated these results with patient age, race and serum PSA concentration. We performed multivariate logistic regression analysis to predict cancer based on clinical characteristics, and evaluated the positive predictive value of digital rectal examination for detecting cancer as stratified by race and PSA. RESULTS: Of the men 70% underwent biopsy with no difference in compliance according to age, race or PSA level. The 13% cancer detection rate correlated with age, race and PSA (p <0.003). The positive predictive value of a suspicious digital rectal examination was 5, 14 and 30% in men with PSA 0 to 1.0, 1.1 to 2.5 and 2.6 to 4.0 ng./ml., respectively. All cancers were clinically localized. Of the 72% of cases that were surgically staged 82% were organ confined and 78% were moderately differentiated. CONCLUSIONS: The positive predictive value of suspicious digital rectal examination was appreciable in men with low serum PSA. The majority of cancer cases detected by digital rectal examination had features of clinically important and potentially curable disease.     

Study of free to total prostate specific antigen ratio in the detection of patients with prostate cancer

BACKGROUND: We investigated the clinical usefulness of free to total serum prostate specific antigen (PSA) ratio (F/T ratio) in order to improve the specificity of total PSA measurement for detecting prostate cancer. METHOD: In this study 129 patients with total PSA level 4-20 ng/ml underwent transrectal ultrasound guided sextant biopsy. Serum samples were assessed for total PSA, free PSA and the F/T ratio calculated. All patients were pathologically diagnosed as benign prostatic hyperplasia or prostate cancer. RESULTS: Of 129 patients 21 had prostate carcinoma (PCa) and 108 had benign prostatic hyperplasia (BPH) from the results of prostate biopsies. The mean of total PSA were not significantly different between men with PCa and with BPH. The mean of free PSA for PCa was significantly lower than that for BPH (p = 0.043). Furthermore, the mean of F/T ratio was significantly different between PCa and BPH group (p = 0.0014). The F/T ratio had a higher specificity than total PSA at all levels of sensitivity in detecting prostate cancers. Sensitivity, specificity and accuracy for cancer detection at a cut off 0.12 was 90.4%, 51.8% and 58.1%, respectively. Also, free PSA was as useful as F/T ratio for cancer detection when analyzed in receiver operating characteristic curves analysis. When determined the cut off number of free PSA at 0.78 ng/ml, the sensitivity, specificity and accuracy for cancer detection were 61.9%, 66.7% and 65.9%, respectively. CONCLUSION: This study indicated that the F/T ratio and free PSA could improve the specificity without impairing the sensitivity for detecting PCa in patients with 4-20 ng/ml of total PSA.