Preliminary Results of Clinical Evaluation of the Free/Total Prostate-Specific Antigen Ratio in a Multicentric Study

Aims and Background

The free/total (F/T) prostate-specific antigen (PSA) ratio is probably the most promising tool proposed to increase the specificity of PSA in the diagnosis of prostate cancer. The aim of the present study was to evaluate the clinical value of the F/T ratio in 138 patients with benign hyperplasia, 101 with untreated prostate cancer, and 176 apparently healthy men.

Methods

We used a new immunometric assay of free PSA (FPSA-RIACT, CIS Diagnostici, Italy) which has shown good analytical performance; sample handling and storage under routine conditions did not affect the antigen stability.

Results

The diagnostic efficiency of the F/T ratio was significantly better than that of total PSA. In patients with total PSA ranging from 4 to 10 ng/ml, at a specificity level of 95% total PSA showed a sensitivity of 7%, whereas the sensitivity of F/T increased to 70%. Using the F/T ratio as a decision tool in association with total PSA and considering all cases candidate to biopsy (total PSA greater than 3.79 ng/ml corresponding to the 95% level), we demonstrated a 35% reduction of total biopsies that would have been required on the basis of total PSA alone.

Conclusions

The determination of the percentage of F/T serum PSA significantly improves the specificity of the marker, particularly in the 4-10 ng/ml dose range where unnecessary prostate biopsies can be reduced.

Third-Generation Psa: Ultrasensitive or Ultraprecise Assay?

The ultrasensitive PSA assay has been recently acknowledged as a useful tool for the monitoring of patients prostatectomized for prostatic cancer. We have evaluated a commercially available ultrasensitive PSA assay (Immulite Third Generation PSA - DPC - Los Angeles CA) in comparison with the routinely used PSA (Immulite PSA - DPC - Los Angeles CA). When evaluated with different approaches, the analytical sensitivity of ultrasensitive PSA ranged between 0.0029 and 0.0038 ng/ml. The biological detection limit was 0.0098 ng/ml. Dilution of samples with low PSA levels showed a good recovery (from 88 to 113%) up to 1:128 dilution factor (final PSA levels ranging from 0.004 to 0.016 ng/ml in different samples). The assay precision was excellent in the low dose range, the highest interassay interadjustment CV among replicates being 5.84% when assaying serum samples with PSA lower than 1.0 ng/ml.

Besides its role in the follow-up of prostatectomized patients, the evaluated ultrasensitive PSA could be reliably used for the detection of clinically meaningful PSA variations in the low dose range, and it could therefore be a candidate for the assessment of PSA velocity.

How Tumor Markers are used in the Routine Follow-up of Breast and Colorectal Cancer. A Survey of 29 Italian Hospitals

The impact of tumor markers on the outcome of several malignancies is still under debate. This relative uncertainty leads to a subjective approach to their use. Monitoring the use of tumor markers is a valuable tool to identify the need for educational policies. We conducted a survey to evaluate how tumor markers are routinely used in the follow-up of patients with breast, colorectal and ovarian carcinoma. The former two malignancies are considered in the present paper. We surveyed 35 Italian hospitals; 29 (83%, accounting for 26,622 hospital beds) filled in and returned the questionnaire. Overall, 467,361 tumor marker requests were scrutinized by the surveyed hospitals. We found a wide variability in the type and number of routinely used markers, the cutoff points chosen, and the clinical decisions taken on the basis of marker results. In addition, we observed a relative lack of communication between clinicians and clinical pathologists in around 50% of the surveyed hospitals. In these cases clinical information was not provided to the laboratory and methodological aspects were not communicated to clinicians. From the findings of the present study we conclude that the cooperation between clinicians and clinical pathologists must improve before guidelines for the use of tumor marker assays can be framed and the compliance with these guidelines can be checked. Request forms for tumor marker assays should therefore be designed to contain clinical information and the quality of filling in request forms with clinical data should be carefully monitored.

Prostate Cancer Probability after Total PSA and Percent Free PSA Determination

The percent free PSA value is a promising diagnostic tool for prostate cancer. However, its actual role has not yet been established because of the widely diverging sensitivity and specificity values. This could depend at least in part on analytical difficulties, since the free PSA concentration is much lower than that of total PSA. The present investigation was designed to evaluate the diagnostic performance of the percent free PSA in the most favorable analytical conditions.

Materials and methods

81 patients affected by newly diagnosed, untreated primary prostate cancer (CaP) and 239 patients with untreated benign prostatic hyperplasia (BPH) were prospectively enrolled. Hybritech total and free PSA were measured by the same technician using the same reagent batch.

Results

The percent free PSA was not significantly associated with age, tumor stage, gland volume, Gleason score, and total PSA, nor was it significantly affected by concomitant prostatic complications either in CaP or BPH. Percent free PSA was more effective than total PSA in the differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. Percent free PSA determination could have reduced the rate of unnecessary biopsies in cases with total PSA ≥ 4 ng/mL and ≥ 10 ng/mL (avoided biopsies 61% and 63%, respectively). The post-test probability of the disease, which represents the proportion of patients with a positive percent free PSA value who have the disease, was, however, relatively low in younger patients with total PSA within the normal range.

Conclusions

The diagnostic performance of the percent free PSA value is enhanced when the methodological variability is reduced, particularly in men with low total PSA. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 ng/mL. The percent free PSA value is effective in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 or 10 ng/mL. However, due to its relatively low post-test probability, the percent free PSA value should be interpreted with caution in the decision-making related to individual patients and should be used in association with clinical and instrumental evaluation of the patient.

How CA 125 is used in the routine follow-up of ovarian cancer: a survey of 29 Italian hospitals

Tumor markers are currently monitored on a routine basis. However, their impact on the course of a disease is still under debate. This relative uncertainty leads to a subjective approach to their use. In order to evaluate the range in the pattern of tumor marker application we carried out a survey on the follow-up of patients with ovarian, breast, and colorectal carcinomas. This report concerns only ovarian cancer. Preliminary results showed that the number of markers used, the cutoff point and, probably of major importance, the management of patients with positive tumor marker vary considerably. When evaluating the institutional setting of the surveyed hospitals, a relatively poor interaction between clinicians and the laboratory staff was found. Actually, in about half of the investigated centers, clinical information is not provided to the laboratory staff and methodological aspects are not reported to clinicians, too. The first step to increase the effectiveness of tumor markers is to improve cooperation between persons assaying the markers and those using them. This is a mandatory task in order to both enable the application of recommendations provided by guidelines and to provide the means to verify their rate of acceptance.

Clinical evaluation of percent free prostate-specific antigen using the AxSYM system in the best analytical scenario

OBJECTIVE

Percent free prostate-specific antigen (PSA) is a promising tool for prostate cancer (CaP) diagnosis. However, its diagnostic performances have not yet been established. The present study was carried out with the aim of evaluating percent free PSA in the most favourable analytical conditions.

MATERIALS AND METHODS

Eighty-eight patients affected by newly diagnosed, untreated, primary CaP, and 169 cases with biopsy-confirmed, untreated, benign prostatic hypertrophy (BPH) were prospectively enrolled. Abbott AxSYM total and free PSA were measured by the same technician using the same instrument and the same reagent batch.

RESULTS

Percent free PSA was more effective than total PSA in differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. In cases with total PSA >4 microg/l, percent free PSA could have reduced by about 50% the rate of unnecessary biopsies with a probably still acceptable 93% cancer detection rate. The likelihood of CaP after the determination of percent free PSA was in fact higher than 50% using cut-off points which provide low sensitivity values (i.e. 58% in men aged 50-59 years).

CONCLUSIONS

Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/l and in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 microg/l. However, percent free PSA should be cautiously interpreted in decision making in individual patients since post-test probability is relatively low in men aged 50-70 years.

Percent free prostate-specific antigen in assessing the probability of prostate cancer under optimal analytical conditions

Although general consensus exists that percent free prostate-specific antigen (PSA) is superior to total immunoreactive PSA for prostate cancer (CaP) detection, its diagnostic performance is not yet well established. Analytical problems may account for difficulties in evaluating percent free PSA because the free PSA concentration is substantially lower than that of total PSA. The aim of the present study was to establish the diagnostic performances of the IMMULITE percent free PSA assay from Diagnostics Products Corp. under experimental conditions optimized to minimize analytical variability. Eighty-five patients with untreated primary CaP and 261 with untreated benign prostate hypertrophy (BPH) were prospectively enrolled. The Diagnostics Products IMMULITE total (Third Generation) and free PSA were measured by the same technician, using the same instrument and the same reagent batch. We calculated the post-test probability to express how the likelihood of the diagnosis of CaP changed after the percent free PSA was determined. Areas under the ROC curves of percent free PSA were better than those of total PSA in every evaluated range of total PSA. The percent free PSA could have reduced the rate of unnecessary biopsies by 47% in patients with total PSA >/=4 microg/L with only 3.8% false-negative results. The post-test probability of percent free PSA was, however, <50% in men 50-70 years of age, using cutoff points providing sensitivity from 99% to 80%. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/L. In men with low total PSA, the diagnostic performance of the percent free PSA assay may be optimized by controlling methodological variability. The percent free PSA assay is effective in reducing the rate of unnecessary biopsies in men with total PSA >4 microg/L. However, the post-test probability provided by percent free PSA is relatively low in asymptomatic patients 50-70 years of age.

How tumor markers are used in the routine follow-up of breast and colorectal cancer. A survey of 29 Italian hospitals

The impact of tumor markers on the outcome of several malignancies is still under debate. This relative uncertainty leads to a subjective approach to their use. Monitoring the use of tumor markers is a valuable tool to identify the need for educational policies. We conducted a survey to evaluate how tumor markers are routinely used in the follow-up of patients with breast, colorectal and ovarian carcinoma. The former two malignancies are considered in the present paper. We surveyed 35 Italian hospitals; 29 (83%, accounting for 26,622 hospital beds) filled in and returned the questionnaire. Overall, 467,361 tumor marker requests were scrutinized by the surveyed hospitals. We found a wide variability in the type and number of routinely used markers, the cutoff points chosen, and the clinical decisions taken on the basis of marker results. In addition, we observed a relative lack of communication between clinicians and clinical pathologists in around 50% of the surveyed hospitals. In these cases clinical information was not provided to the laboratory and methodological aspects were not communicated to clinicians. From the findings of the present study we conclude that the cooperation between clinicians and clinical pathologists must improve before guidelines for the use of tumor marker assays can be framed and the compliance with these guidelines can be checked. Request forms for tumor marker assays should therefore be designed to contain clinical information and the quality of filling in request forms with clinical data should be carefully monitored.

Standardization of assay for cytokeratin-related tumor marker CYFRA21.1 in urine samples

The determination of tumor markers in urine samples has been proposed as an effective diagnostic tool in bladder cancer. The aim of the present investigation was to validate in urine samples the assay of the CYFRA21.1 cytokeratin-related marker, the serum concentrations of which showed promising diagnostic utility in patients with bladder cancer. First-voided urine samples were collected from patients with different malignancies. CYFRA21.1 was assayed with a commercially available enzyme immunoassay (Boehringer Mannheim). Different centrifugation patterns, the use of different buffers and nonionic detergents, and pH variations were evaluated. We demonstrated that: (a) cells and cell debris contain a large amount of CYFRA21.1 and must be eliminated by centrifugation; (b) storage at -20 degrees C causes amorphous precipitate, which may aspecifically bind CYFRA21.1; (c) the latter behavior may be prevented by diluting fresh urine samples with phosphate buffer with nonionic detergent added; (d) pH variations within the range 4.9-8.2 do not significantly affect CYFRA21.1 assay results. Provided that samples are diluted with buffer containing nonionic detergent, the CYFRA21.1 assay showed good precision and accuracy characteristic in urine samples. We therefore propose a standard protocol for the collection of urine samples for CYFRA21.1 assay. In a preliminary clinical evaluation, CYFRA21.1 concentrations in 16 patients with primary bladder cancer were higher than in healthy subjects. In the urine collected in the follow-up of patients treated for bladder cancer, CYFRA21.1 tended to be higher in relapsed patients than in those without evidence of disease. These preliminary data induced us to extend the clinical trial to establish the actual role of this assay in routine use.

Standardization of assay for cytokeratin-related tumor marker CYFRA21.1 in urine samples

The determination of tumor markers in urine samples has been proposed as an effective diagnostic tool in bladder cancer. The aim of the present investigation was to validate in urine samples the assay of the CYFRA21.1 cytokeratin-related marker, the serum concentrations of which showed promising diagnostic utility in patients with bladder cancer. First-voided urine samples were collected from patients with different malignancies. CYFRA21.1 was assayed with a commercially available enzyme immunoassay (Boehringer Mannheim). Different centrifugation patterns, the use of different buffers and nonionic detergents, and pH variations were evaluated. We demonstrated that: (a) cells and cell debris contain a large amount of CYFRA21.1 and must be eliminated by centrifugation; (b) storage at -20 degrees C causes amorphous precipitate, which may aspecifically bind CYFRA21.1; (c) the latter behavior may be prevented by diluting fresh urine samples with phosphate buffer with nonionic detergent added; (d) pH variations within the range 4.9-8.2 do not significantly affect CYFRA21.1 assay results. Provided that samples are diluted with buffer containing nonionic detergent, the CYFRA21.1 assay showed good precision and accuracy characteristic in urine samples. We therefore propose a standard protocol for the collection of urine samples for CYFRA21.1 assay. In a preliminary clinical evaluation, CYFRA21.1 concentrations in 16 patients with primary bladder cancer were higher than in healthy subjects. In the urine collected in the follow-up of patients treated for bladder cancer, CYFRA21.1 tended to be higher in relapsed patients than in those without evidence of disease. These preliminary data induced us to extend the clinical trial to establish the actual role of this assay in routine use.

Dynamic use of tumor markers, rationale-clinical applications and pitfalls

The dynamic evaluation of tumor markers is a promising area of investigation which is expected to provide clinical information when serial samples are available from the same patient. This is feasible in the post-operatory evaluation, during the follow-up after the treatment for to the primary tumor and in the monitoring of the treatment for metastatic disease. Variations among serial samples may be assessed using both empirical and mathematical approaches. Empirical approaches rely on overcoming a given percentage usually chosen on the base of arbitrary decisions. Mathematical approaches include the actual half-life, the doubling time, a dose/time regression analysis and the calculation of the critical difference. The two former are currently used in clinical practice whereas the two latter are still matter of investigation. As concerns the assessment of the radicality of the surgery for the primary tumor, the serum markers are used in germ cell tumors and in prostate cancer. The half-life of the markers is the decision criteria used in germ cell cancers, while in prostate cancer PSA is expected to be undetectable more than 30 days after the radical prostatectomy. Tumor markers are currently used during the follow-up of several malignancies after the treatment for primary tumor. Although several samples are available, decision criteria are still based on positive/negative cut-off values in several instances. Promising dynamic approaches are under investigation and are expected to lead to earlier and probably more accurate information concerning the disease progression. A critical point still under debate is the actual impact of tumor markers on patients' survival in malignancies incurable when metastatic, such as colorectal cancer and breast cancer. This matter urgently demands perspective clinical studies. Finally, the dynamic use of tumor markers is now commonly applied in the monitoring of the therapy for metastatic malignancies. In this clinical setting mathematical criteria are used for ovarian and and germ cell tumors with promising results. Nevertheless, the use of empirical criteria, namely the percentage of variation between two consecutive samples, is successfully used for the monitoring of the therapy of metastatic breast cancer. In conclusion, when several samples are available from an individual patient they may be evaluated according to dynamic criteria instead of referring to a conventional positive/negative cut-off point. Although mathematical decision criteria are expected to provide more reliable data, empirical approaches are used as well and provide useful information in decision making.

PSA in prostate cancer: Criticai evaluation of clinically available assay methods

PSA is probably the most commonly used tumour marker in oncology. The absolute tissue specificity of PSA, as well as its well-established rote in clinical decision making, nave certainly contributed to its widespread use. Nevertheless, the familiarity that comes from the frequent use of the marker prompts the need for the awareness of the impact of the methods on the interpretation of the assay results. Actually, PSA values obtained by different methods may vary. Differences may be of clinical relevance in some instances such as when evaluating a PSA value with reference to a given cut-off point or, mainly, when assessing any variation among serial samples from the same patient. This potential variability related to the method is due to the molecular heterogeneity of PSA as well as to the lack of standard reference material. The problem of the binding of PSA to circulating protease inhibitors is of major relevance. The occurrence of several PSA isoforms should also be taken into account. Both a strict standardization of the method and the preparation of a reference standard are expected to reduce the method-related variability. In the meantime, the same assay method should be used to monitor the same patient. Moreover, dose co-operation between the urologist and the clinical pathologist is mandatory in order to be aware of the methodological clues which eventually may affect the decision-making process.

Tumor markers in breast cancer follow-up: a potentially useful parameter still awaiting definitive assessment. Forza Operativa Nazionale sul Carcinoma Mammario (FONCaM)

BACKGROUND

Although tumor markers are frequently used in the follow-up of patients with breast cancer, two points are still being debated: 1) their cost/effectiveness has been neither demonstrated nor disproved; 2) the reliability of the currently used dichotomous division into a positive/negative cut-off should be definitely validated. Dynamic criteria of interpretation based on serial serum samples would probably be more effective for early detection of relapse.

PATIENTS AND METHODS

The aim of the present study was to compare the dichotomous cut-off based decision criteria to a dynamic serial sample based assessment of tumor markers. Since 1989, 794 patients have been followed in 11 institutions. CEA and CA15.3 were measured once a month for three months before every clinical examination. The present paper concerns the evaluation variability in 405 patients without evidence of disease in the first three institutions joining the study.

RESULTS

In patients without evidence of disease, the coefficient of variation of all samples for every patient showed a median value of 19 for CEA and 21 for CA15.3. Variability was negatively associated with the antigen level and was most likely due to the analytical component. This was also confirmed by the significant difference in variability among the three institutions evaluated. The median value of the critical difference was 53% for CEA and 57% for CA15.3.

CONCLUSIONS

1) Individually tailored dynamic decision criteria are applicable in about 50% of the cases. 2) The problem of improving the precision of tumor marker assays in the low dose range must be urgently addressed to the manufacturers of tumor markers by the scientific community in order to apply individually tailored decision criteria for patients in whom the serum level of biological markers is low.

Prostate-specific antigen as a unique routine test in monitoring therapy for inoperable prostate cancer: comparison with radionuclide bone scan and prostatic acid phosphatase

The aim of the present investigation was the evaluation of cost-effectiveness of variables used in monitoring patients with inoperable prostate cancer. Prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), and radionuclide bone scan were considered. The tumor marker positivity was assessed according to dynamic criteria (> 50% increase between consecutive samples). 108 patients entered the study; 72 patients treated with a luteinizing hormone-releasing hormone analogue were followed up for periods ranging from 12 to 64 months. PSA and PAP levels were measured using immunometric assays. Both cutoff-based and dynamic, serial sample-based decision criteria were employed. With respect to a positive bone scan, PSA showed negative predictive values of 82 and 77%, respectively, using 4 and 10 ng/ml as cutoff points. Progression of the disease to the bone occurred in 20 patients: in 17 PSA was the first indicator of progression, in the other 3 PAP anticipated PSA for a very short time (3-4 months), which was not of relevance to clinical decisions. PAP is less specific and sensitive than PSA; PAP may eventually provide information on disease status in a limited percentage of patients with advanced prostate cancer treated with androgen ablation, being differently regulated with respect to PSA. No increasing PSA profile was detected in patients who responded to the therapy. From the results of the present investigation, we draw the following conclusions: (1) PSA can be used reliably as a unique tool in the follow-up of patients for the early detection of progressive disease, and (2) dynamic criteria of evaluation of serial PSA determinations probably provide more effective and earlier clinical information.

Tissue polypeptide antigen and tissue polypeptide specific antigen in primary breast cancer. Evaluation in serum and tumour tissue

Tissue polypeptide antigen, measured by both a polyclonal antibody (TPA IRMA Prolifigen) and a monoclonal antibody prototype kit (TPA-M IRMA Prolifigen), and the tissue polypeptide specific antigen were evaluated. The markers were measured in 266 serum samples and in 291 tumour cytosols from patients with primary breast cancer. The three markers were available in matched pairs of both serum and cytosol from the same patient in 144 cases. Diagnostic sensitivity of serum levels of the three markers was not significantly different when using cut-off values calculated on the basis of healthy subjects. In the cytosol, tissue polypeptide antigen (TPA IRMA), tissue polypeptide antigen (TPA-M IRMA) and tissue polypeptide specific antigen were significantly correlated with steroid receptor status, while their serum levels were not. Cytosol and serum levels of the three markers were not significantly associated. All three were significantly correlated both in serum and in cytosol. The association was closer between tissue polypeptide antigen (TPA IRMA) and tissue polypeptide antigen (TPA-M IRMA) than between each of these two markers and tissue polypeptide specific antigen. From these findings we draw the following conclusions: 1. Tissue polypeptide specific antigen (TPA IRMA) and tissue polypeptide antigen (TPA-M IRMA) probably provide superimposable information both in serum and in cytosol; 2. Tissue polypeptide specific antigen and tissue polypeptide antigen (TPA IRMA) or tissue polypeptide antigen (TPA-M IRMA), although closely associated, probably measure in part different cytokeratins. Therefore, they should not be considered interchangeable in individual patients; 3. The determination of the markers in serum and in cytosol provides different information concerning the tumour phenotype.