Usefulness of the nadir value of serum prostate-specific antigen measured by an ultrasensitive assay as a predictor of biochemical recurrence after radical prostatectomy for clinically localized prostate cancer

Prostate-Specific Antigen as an Ultrasensitive Biomarker for Patients with Early Recurrent Prostate Cancer: How Low Shall We Go? A Systematic Review

Serum prostate-specific antigen (PSA) needs to be monitored with ultrasensitive PSA assays (uPSAs) for oncologists to be able to start salvage radiotherapy (SRT) while PSA is <0.5 µg/L for patients with prostate cancer (PCa) relapsing after a radical prostatectomy (RP). Our systematic review (SR) aimed to summarize uPSAs for patients with localized PCa. The SR was registered as InPLASY2023110084. We searched for studies on Google Scholar, PUBMED and reference lists of reviews and studies. We only included studies on uPSAs published in English and excluded studies of women, animals, sarcoidosis and reviews. Of the 115 included studies, 39 reported PSA assay methods and 76 reported clinical findings. Of 67,479 patients, 14,965 developed PSA recurrence (PSAR) and 2663 died. Extremely low PSA nadir and early developments of PSA separated PSAR-prone from non-PSAR-prone patients (cumulative p value 3.7 × 1012). RP patients with the lowest post-surgery PSA nadir and patients who had the lowest PSA at SRT had the fewest deaths. In conclusion, PSA for patients with localized PCa in the pre-PSAR phase of PCa is strongly associated with later PSAR and survival. A rising but still exceedingly low PSA at SRT predicts a good 5-year overall survival.

[PROSTATE-SPECIFIC ANTIGEN LEVEL AT 6 MONTHS AFTER RADICAL PROSTATECTOMY ENABLES STRATIFICATION OF FOLLOW-UP PERIODS IN THE CANCER REGIONAL ALLIANCES CRITICAL PATH]

(Objectives)Factors related to prostate-specific antigen (PSA) recurrence, including PSA at 6 months after radical prostatectomy, were evaluated to determine if the postoperative follow-up period in the cancer regional alliances critical path could be individualized using a coordinated path. (Patients and methods)Among 352 patients who underwent laparoscopic radical prostatectomy at our hospital from May 2009 to June 2015, 331 who did not undergo preoperative hormone therapy were examined retrospectively. Cases with PSA < 0.01 ng/mL at 6 months after surgery (group A, n=209) were compared with those with PSA > 0.01 ng/mL at the same time point (group B, n=122). (Results)PSA recurrence was significantly higher in group B (n=21 (10.0%) vs. n=70 (57.4%), p< 0.001) and the time to recurrence was significantly shorter (44 vs.12.5 months, p< 0.001). In multivariate analysis within group A, the Gleason Grade Group (GGG) and extraprostatic extension in surgical specimens were predictors of PSA recurrence. In group A, all cases (n=30) of GGG1 in surgical specimens had no extraprostatic extension and no PSA recurrence. There were 90 cases of surgical specimens with GGG2 and no extracapsular infiltration, and only 4 of these cases had recurrence (4.4%). (Conclusion)The results of the study indicate that follow-up interval stratification is possible using the PSA level at 6 months after radical prostatectomy, GGG and extraprostatic extension in the surgical specimen.

Determining When to Stop Prostate Specific Antigen Monitoring after Radical Prostatectomy: the Role of Ultrasensitive Prostate Specific Antigen

PURPOSE

We analyzed long-term followup data after radical prostatectomy to determine how long we should follow patients in whom the serum prostate specific antigen level measured by an ultrasensitive assay was consistently low.

MATERIALS AND METHODS

We retrospectively reviewed clinicopathological data for 582 consecutive patients who underwent open or laparoscopic radical prostatectomy between 1995 and 2004, excluding 4 patients who received adjuvant therapy. We stratified the patients according to prostate specific antigen at 3 and 5 years after surgery, and examined subsequent biochemical recurrence (elevation of prostate specific antigen to greater than 0.2 ng/ml) during followup. Mean followup was 9.7 years.

RESULTS

At 3 years after surgery prostate specific antigen levels were measured by an ultrasensitive assay in 323 patients who had not experienced biochemical recurrence. In 187 patients with undetectable prostate specific antigen levels (less than 0.01 ng/ml) the 10 and 15-year biochemical recurrence-free survival rates were 99% and 96%, respectively. At 5 years after surgery prostate specific antigen was measured in 315 patients by the ultrasensitive assay. In 162 patients with undetectable prostate specific antigen levels the 10 and 15-year biochemical recurrence-free survival rates were both 100%. In this group the prostate specific antigen level at last followup was less than 0.01 ng/ml in 132 patients, 0.01 to 0.03 ng/ml in 27 patients, and 0.06 ng/ml, 0.07 ng/ml and 0.11 ng/ml in 1 patient each.

CONCLUSIONS

This long-term review indicates that if patients have continuously undetectable prostate specific antigen levels by an ultrasensitive assay for 5 years, prostate specific antigen monitoring can be stopped with an extremely low risk of subsequent biochemical recurrence.

Prostate cancer magnetic resonance imaging (MRI): multidisciplinary standpoint

Prostate cancer is the most common cancer diagnosed in men and a leading cause of death. Accurate assessment is a prerequisite for optimal clinical management and therapy selection of prostate cancer. There are several parameters and nomograms to differentiate between patients with clinically insignificant disease and patients in need of treatment. Magnetic resonance imaging (MRI) is a technique which provides more detailed anatomical images due to high spatial resolution, superior contrast resolution, and multiplanar capability. State-of-the-art MRI techniques, such as diffusion weighted imaging (DWI), MR spectroscopic imaging (MRSI), dynamic contrast enhanced MRI (DCE-MRI), improve interpretation of prostate cancer imaging. In this article, we review the major role of MRI in the advanced management of prostate cancer to noninvasively improve tumor staging, biologic potential, treatment planning, therapy response, local recurrence, and to guide target biopsy for clinical suspected cancer with previous negative biopsy. Finally, future challenges and opportunities in prostate cancer management in the area of functional MRI are discussed as well.

Prostate cancer imaging: what the urologist wants to know

No consensus exists at present regarding the use of imaging for the evaluation of prostate cancer. Ultrasonography is mainly used for biopsy guidance and magnetic resonance imaging is the mainstay in evaluating the extent of local tumor. Computed tomography and radionuclide bone scanning are mainly reserved for assessment of advanced disease. Positron emission tomography is gaining acceptance in the evaluation of treatment response and recurrence. The combination of anatomic, functional, and metabolic imaging modalities has promise to improve treatment. This article reviews current imaging techniques and touches on the evolving technologies being used for detection and follow-up of prostate cancer.

Fifth-generation digital immunoassay for prostate-specific antigen by single molecule array technology

BACKGROUND

Measurement of prostate-specific antigen (PSA) in prostate cancer patients following radical prostatectomy (RP) has been hindered by the limit of quantification of available assays. Because radical prostatectomy removes the tissue responsible for PSA production, postsurgical PSA is typically undetectable with current assay methods. Evidence suggests, however, that more sensitive determination of PSA status following RP could improve assessment of patient prognosis and response to treatment and better target secondary therapy for those who may benefit most. We developed an investigational digital immunoassay with a limit of quantification 2 logs lower than current ultrasensitive third-generation PSA assays.

METHODS

We developed reagents for a bead-based ELISA for use with high-density arrays of femtoliter-volume wells. Anti-PSA capture beads with immunocomplexes and associated enzyme labels were singulated within the wells of the arrays and interrogated for the presence of enzymatic product. We characterized analytical performance, compared its accuracy with a commercially available test, and analyzed longitudinal serum samples from a pilot study of 33 RP patients.

RESULTS

The assay exhibited a functional sensitivity (20% interassay CV) <0.05 pg/mL, total imprecision <10% from 1 to 50 pg/mL, and excellent agreement with the comparator method. All RP samples were well within the assay measurement capability. PSA concentrations following surgery were found to be predictive of prostate cancer recurrence risk over 5 years.

CONCLUSIONS

The robust 2-log improvement in limit of quantification relative to current ultrasensitive assays and the validated analytical performance of the assay allow for accurate assessment of PSA status after RP.

Persistently elevated prostate-specific antigen at six weeks after radical prostatectomy helps in early identification of patients who are likely to recur

OBJECTIVE

To determine the prognostic factors of biochemical recurrence in patients who failed to achieve an undetectable prostate-specific antigen (PSA) after radical prostatectomy (RP) for prostate cancer.

MATERIALS AND METHODS

We reviewed data on 240 men who underwent RP as first-line treatment and who had a PSA assay available at 6 weeks after surgery. Persistent detectable PSA was defined as a PSA level ≥ 0.1 ng/ml at 6 weeks after surgery.

RESULTS

Overall, 83 men presented persistently elevated PSA after RP and 81 had a biochemical recurrence. Median follow-up was 44 months. In univariate analysis, these factors were associated with biochemical recurrence: preoperative PSA level (P < 0.0001), biopsy and pathologic Gleason score (P < 0.001), capsular involvement (P = 0.0001), positive surgical margins (P < 0.0001), pathological stage ≥ T3 (P = 0.0001), and detectable post-operative PSA ≥ 0.1 ng/ml (P = 0.0001). In a multivariate analysis, only the detectable post-operative PSA level ≥ 0.1 ng/mL (P = 0.001), positive surgical margins (P = 0.002), and pathological stage ≥ T3 (P < 0.001) were significant. The individual, five-year, PSA-free survival rate for men with post-operative PSA <0.1 ng/ml and ≥ 0.1 ng/ml were 59 and 42%, respectively (P < 0.001).

CONCLUSIONS

A majority of patients who failed to achieve an undetectable PSA after surgery had a subsequent biochemical recurrence in the outcome. A systematic PSA assay 6 weeks after RP could be useful to early identify patients who are likely to recur.

Cancer biomarker discovery: the entropic hallmark

Background

It is a commonly accepted belief that cancer cells modify their transcriptional state during the progression of the disease. We propose that the progression of cancer cells towards malignant phenotypes can be efficiently tracked using high-throughput technologies that follow the gradual changes observed in the gene expression profiles by employing Shannon's mathematical theory of communication. Methods based on Information Theory can then quantify the divergence of cancer cells' transcriptional profiles from those of normally appearing cells of the originating tissues. The relevance of the proposed methods can be evaluated using microarray datasets available in the public domain but the method is in principle applicable to other high-throughput methods.

Methodology/Principal Findings

Using melanoma and prostate cancer datasets we illustrate how it is possible to employ Shannon Entropy and the Jensen-Shannon divergence to trace the transcriptional changes progression of the disease. We establish how the variations of these two measures correlate with established biomarkers of cancer progression. The Information Theory measures allow us to identify novel biomarkers for both progressive and relatively more sudden transcriptional changes leading to malignant phenotypes. At the same time, the methodology was able to validate a large number of genes and processes that seem to be implicated in the progression of melanoma and prostate cancer.

Conclusions/Significance

We thus present a quantitative guiding rule, a new unifying hallmark of cancer: the cancer cell's transcriptome changes lead to measurable observed transitions of Normalized Shannon Entropy values (as measured by high-througput technologies). At the same time, tumor cells increment their divergence from the normal tissue profile increasing their disorder via creation of states that we might not directly measure. This unifying hallmark allows, via the the Jensen-Shannon divergence, to identify the arrow of time of the processes from the gene expression profiles, and helps to map the phenotypical and molecular hallmarks of specific cancer subtypes. The deep mathematical basis of the approach allows us to suggest that this principle is, hopefully, of general applicability for other diseases.

Definition and preoperative predictors of persistently elevated prostate-specific antigen after radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) database

OBJECTIVES

To define a level of persistently elevated prostate-specific antigen (PSA) after radical prostatectomy (RP) that equates with high-risk for disease progression, and to identify preoperative predictors of PSA persistence among men from the Shared Equal Access Regional Cancer Hospital (SEARCH) database.

PATIENTS AND METHODS

A total of 901 men treated with RP between 2001 and 2008 were separated into groups based upon PSA nadir within 6 months after RP. We explored the association between nadir groups and time to biochemical recurrence (BCR) using multivariate Cox proportional hazards and determined the preoperative predictors of PSA persistence using logistic regression.

RESULTS

Relative to men with undetectable PSA levels, those with a PSA nadir of 0.03 (hazard ratio [HR] 3.88, P < 0.001), 0.04 (HR 4.87, P < 0.001), 0.05-0.09 (HR 12.69, P < 0.001), 0.1-0.19 (HR 13.17, P < 0.001), and 0.2 ng/mL (HR 13.23, P < 0.001) were at increased risk of BCR while men with a nadir of 0.01 (HR 1.36, P = 0.400) and 0.02 (HR 1.64, P = 0.180) were not. Using the PSA persistence definition of a PSA nadir > or = 0.03 ng/mL, 230 men (26%) had persistence. The independent preoperative predictors of PSA persistence were higher body mass index (BMI, P = 0.002), pathological Gleason score (relative to 2-6: 4 + 3-10, P = 0.001) and preoperative PSA level (P < 0.001).

CONCLUSIONS

Men with a PSA nadir > or = 0.03 ng/mL after RP were at higher risk for BCR. Using a PSA persistence definition of a PSA nadir > or = 0.03 ng/mL, persistence was predicted by known factors associated with aggressive disease (tumour grade, PSA level and BMI). Validation of the present definition in different populations using later end-points remains necessary to assess its prognostic usefulness.

Ultrasensitive prostate specific antigen assay following laparoscopic radical prostatectomy--an outcome measure for defining the learning curve

INTRODUCTION

Radical retropubic prostatectomy (RRP) performed laparoscopically is a popular treatment with curative intent for organ-confined prostate cancer. After surgery, prostate specific antigen (PSA) levels drop to low levels which can be measured with ultrasensitive assays. This has been described in the literature for open RRP but not for laparoscopic RRP. This paper describes PSA changes in the first 300 consecutive patients undergoing non-robotic laparoscopic RRP by a single surgeon.

OBJECTIVES

To use ultrasensitive PSA (uPSA) assays to measure a PSA nadir in patients having laparoscopic radical prostatectomy below levels recorded by standard assays. The aim was to use uPSA nadir at 3 months' post-prostatectomy as an early surrogate end-point of oncological outcome. In so doing, laparoscopic oncological outcomes could then be compared with published results from other open radical prostatectomy series with similar end-points. Furthermore, this end-point could be used in the assessment of the surgeon's learning curve.

PATIENTS AND METHODS

Prospective, comprehensive, demographic, clinical, biochemical and operative data were collected from all patients undergoing non-robotic laparoscopic RRP. We present data from the first 300 consecutive patients undergoing laparoscopic RRP by a single surgeon. uPSA was measured every 3 months post surgery.

RESULTS

Median follow-up was 29 months (minimum 3 months). The likelihood of reaching a uPSA of < or = 0.01 ng/ml at 3 months is 73% for the first 100 patients. This is statistically lower when compared with 83% (P < 0.05) for the second 100 patients and 80% for the third 100 patients (P < 0.05). Overall, 84% of patients with pT2 disease and 66% patients with pT3 disease had a uPSA of < or = 0.01 ng/ml at 3 months. Pre-operative PSA, PSA density and Gleason score were not correlated with outcome as determined by a uPSA of < or = 0.01 ng/ml at 3 months. Positive margins correlate with outcome as determined by a uPSA of < or = 0.01 ng/ml at 3 months but operative time and tumour volume do not (P < 0.05). Attempt at nerve sparing had no adverse effect on achieving a uPSA of < or = 0.01 ng/ml at 3 months.

CONCLUSIONS

uPSA can be used as an early end-point in the analysis of oncological outcomes after radical prostatectomy. It is one of many measures that can be used in calculating a surgeon's learning curve for laparoscopic radical prostatectomy and in bench-marking performance. With experience, a surgeon can achieve in excess of an 80% chance of obtaining a uPSA nadir of < or = 0.01 ng/ml at 3 months after laparoscopic RRP for a British population. This is equivalent to most published open series.

Dynamic contrast-enhanced magnetic resonance imaging in prostate cancer

Prostate cancer remains a major health concern for the male population. During the past decade, a dramatic increase in prostate-specific antigen and transurethral resection of the prostate has resulted in increased detection rate of small lesions and increased incidence of this disease. Needle biopsies in asymptomatic men have also contributed to the increased incidence of prostate cancer, leading to an increasing incidence-to-mortality ratio. Magnetic resonance imaging (MRI) is the modality of choice in prostate cancer patients with increased prostate-specific antigen levels before or after prostate cancer diagnosis confirmed by biopsy and T2-weighted imaging (T2W) has been used as a standard technique in detection. During the last decade, dynamic contrast-enhanced MRI has emerged as one of the main techniques used in multiparametric MRI of the prostate gland in cancer patients. Dynamic contrast-enhanced MRI has been routinely used for detection and diagnosis of the tumor, for staging and monitoring the therapeutic response, as well as for guiding targeted biopsies in patients with suspected prostate cancer or with a negative biopsy result. In this article, we are going to review the analysis techniques of dynamic contrast-enhanced MRI and its various clinical applications in prostate cancer patients.

Role of dynamic contrast-enhanced magnetic resonance (MR) imaging and proton MR spectroscopic imaging in the detection of local recurrence after radical prostatectomy for prostate cancer

OBJECTIVES

To assess the accuracy of magnetic resonance (MR) spectroscopic imaging (1H-MRSI) and dynamic contrast-enhanced MR (DCEMR) in the depiction of local prostate cancer recurrence in patients with biochemical progression after radical prostatectomy (RP).

MATERIALS AND METHODS

1H-MRSI and DCEMR were performed in 70 patients at high risk of local recurrence after RP. The population was divided on the basis of the clinical validation of MR results with the use of a transrectal ultrasound biopsy examination in a group of 50 patients (group A) and the prostate-specific antigen (PSA) serum level restitution after external beam radiotherapy, in a group of 20 patients (group B).

RESULTS

In group A, 1H-MRSI analysis alone showed a sensitivity of 84% and a specificity of 88%; the DCEMR analysis alone, a sensitivity of 71% and a specificity of 94%; combined 1HMRSI-DCEMR, a sensitivity of 87% and specificity of 94%. Areas under the receiver operating characteristic (ROC) curve for 1HMRSI, DCEMR, and combined 1HMRSI /DCEMR were 0.942, 0.93,1 and 0.964, respectively. In group B, 1HMRSI alone showed a sensitivity of 71% and a specificity of 83%; DCEMR, a sensitivity of 79% and a specificity of 100%; combined 1HMRSI and DCEMR, a sensitivity of 86% and a specificity of 100%. Areas under the ROC curve for each of these groups were 0.81, 0.923, and 0.94, respectively.

CONCLUSION

Our results show that combined 1H-MRSI and DCMRE is an accurate method to identify local prostate cancer recurrence in patients with biochemical progression after RP.