Prognostic Significance of Undetectable Ultrasensitive Prostate-specific Antigen Nadir After Radical Prostatectomy

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.

Favorable prognosis of patients who received adjuvant androgen deprivation therapy after radiotherapy achieving undetectable levels of prostate-specific antigen in high- or very high-risk prostate cancer

Introduction

To determine the prognostic significance of long-term adjuvant androgen deprivation therapy (A-ADT) over 1 year in achieving undetectable levels of prostate-specific antigen (PSA) less than 0.001 ng/mL in prostate cancer patients with high- or very high-risk prostate cancer who underwent radiotherapy (RT).

Materials and methods

A total of 197 patients with prostate cancer received RT, with a follow-up of ≥12 months. Biochemical failure was defined as PSA ≥nadir + 2 ng/mL after RT. We analyzed clinical outcomes, including survival, failure patterns, and prognostic factors affecting outcomes.

Results

Biochemical failure-free survival (BCFFS), clinical failure-free survival, distant metastasis-free survival, cancer-specific survival, and overall survival (OS) rates at 5 years were 91.1%, 95.4%, 96.9%, 99.5%, and 89.1%, respectively. Administration of long-term A-ADT significantly predicted favorable BCFFS (p = 0.027) and OS (p < 0.001) in multivariate analysis. Nadir PSA ≤0.001 ng/mL was an independent prognostic factor for BCFFS (p = 0.006) and OS (p = 0.021). The use of long-term A-ADT significantly affected nadir PSA ≤0.001 ng/mL (p < 0.001). The patients with A-ADT for 1 year or longer had better BCFFS or OS than those for less than 1 year or those without A-ADT (p < 0.001). The best prognosis was demonstrated in patients treated with long-term A-ADT and nadir PSA ≤0.001 ng/mL in BCFFS (p < 0.001).

Conclusion

The addition of long-term A-ADT over 1 year to RT demonstrated good treatment outcomes in patients with locally advanced prostate cancer. Achieving a nadir PSA value ≤0.001 ng/mL using combination therapy with RT and A-ADT is a powerful clinical predictor of treatment outcomes.

Ultrasensitive prostate-specific antigen level as a predictor of biochemical progression after robot-assisted radical prostatectomy: Towards risk adapted follow-up

BACKGROUND

Ultrasensitive prostate-specific antigen (USPSA) is useful for stratifying patients according to their USPSA-based risk. Aim of our study was to determine the usefulness of USPSA as predictor of biochemical recurrence (BCR) after robot-assisted radical prostatectomy (RARP).

METHODS

This retrospective study included 213 prostate cancer patients who had a postoperative USPSA between 0.01 and 0.2 ng/mL and at least 2 years of follow-up. We developed predictive models for BCR with PSA ≥0.2 and ≥0.5 ng/mL.

RESULTS

A total of 103 patients (48.3%) had BCR at a median follow-up of 13.3 months. Higher postoperative USPSA (odds ratio [OR] = 4.73, P < 0.01), bilateral positive surgical margin in both sides (OR = 1.32, P = 0.044), higher average PSA rise (OR = 1.67, P = 0.031), ISUP grade group ≥3 (OR = 1.48, P = 0.003), and shorter interval since RARP (OR = 0.58, P < 0.001) were independent predictors of BCR with PSA ≥0.2 ng/mL. Higher postoperative USPSA (OR = 3.85, P < 0.01), bilateral positive surgical margin (OR = 1.34, P = 0.011), ISUP grade group ≥3 (OR = 1.5, P = 0.002), and shorter interval since RARP (OR = 0.61, P = 0.001) were independent predictors of BCR with PSA ≥0.5 ng/mL. The areas under the curve for the first and second model were 0.865 and 0.834, respectively.

CONCLUSION

Ultrasensitive PSA after RARP is a useful prognostic indicator of BCR which could guide postoperative risk stratification and layout follow-up scheduling.

Prediction of biochemical failure using prostate-specific antigen half-life in patients with adverse pathologic features after radical prostatectomy

PURPOSE

Prostate-specific antigen nadir and time to prostate-specific antigen nadir are predictors of disease progression in patients who undergo radical prostatectomy. However, a mutually conflicting relationship exists between them. Thus, we compared postoperative prostate-specific antigen levels at the first follow-up with the expected levels while considering the half-life of prostate-specific antigen to improve the prediction of biochemical failure after radical prostatectomy in patients with adverse pathologic features.

METHODS

Patients treated with robot-assisted laparoscopic prostatectomy were enrolled. Patients with a follow-up duration of < 12 months or positive lymphadenectomy results were excluded. "Adverse prostate-specific antigen" was defined as a prostate-specific antigen level higher than the expected level at 6 weeks.

RESULTS

Among 450 patients, adverse pathologic features and adverse prostate-specific antigen were found in 260 (57.8%) and 245 (54.5%) patients, respectively. Analysis of patients with and without abnormal prostate-specific antigen level revealed significantly different biochemical failure-free survival outcomes. Patients with one adverse pathologic feature but without adverse prostate-specific antigen showed similar biochemical failure-free survival to those without adverse pathologic features. Adverse prostate-specific antigen was identified as an independent predictor for biochemical failure within 1 year after radical prostatectomy. The area under the curve when adding adverse prostate-specific antigen to the conventional factors was significantly higher than that for the conventional factors alone.

CONCLUSION

The difference between postoperative prostate-specific antigen levels at the first follow-up visit after radical prostatectomy and the expected level while considering the half-life of prostate-specific antigen is a predictive factor for treatment efficacy following radical prostatectomy.

Timing of Prostate-specific Antigen Nadir After Radical Prostatectomy and Risk of Biochemical Recurrence

OBJECTIVE

To evaluate the association between the prostate-specific antigen (PSA) nadir level and the time to nadir (TTN) with biochemical recurrence (BCR) risk after radical prostatectomy (RP) in the Shared Equal-Access Research Cancer Hospital (SEARCH) database.

MATERIALS AND METHODS

This is a retrospective analysis of 1939 men from the SEARCH database treated with RP between 1998 and 2015 with available ultrasensitive PSA nadir within 1-6 months after RP. Uni- and multivariable analyses of PSA nadir and TTN with time from nadir to BCR were performed with Cox models (adjusted for demographics, tumor features, and preoperative PSA).

RESULTS

Among men with an undetectable PSA nadir, the TTN was unrelated to BCR (1.0-2.9 vs 3-6 months: hazard ratio [HR] 0.86, P = .46). Regardless of TTN, men with detectable nadir had an increased risk of BCR (TTN of 3-6 months: HR 1.81, P = .024; TTN of 1.0-2.99 months: HR 3.75, P <.001 vs undetectable nadir and TTN of 3-6 months). Among men with a detectable PSA at 1-3 months, 53% had a lower PSA level during follow-up 3-6 months after RP, which was undetectable in 32% and lower but still detectable in 21%.

CONCLUSION

In the post-RP setting, men with both a detectable nadir and a shorter TTN had an increased risk of BCR. Intriguingly, about half of the men with a detectable PSA in the first 3 months after RP had a lower PSA level during follow-up between 3 and 6 months after RP. If confirmed in future studies, this has important implications for patients considering adjuvant therapy based on postoperative PSA values in the first 3 months after RP.

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.

Factors influencing biochemical recurrence in patients who have received salvage radiotherapy after radical prostatectomy: a systematic review and meta-analysis

Several studies have evaluated the risk factors influencing biochemical recurrence (BCR) of prostate cancer in patients receiving salvage radiotherapy (SRT) for BCR after radical prostatectomy (RP), but the results remain conflicting. In this study, we performed a meta-analysis to resolve this conflict. We searched the following databases: PubMed, Embase, and Web of Science using the following terms in "All fields": "salvage radiation therapy," "salvage IMRT," "S-IMRT," "salvage radiotherapy," "SRT," "radical prostatectomy," "RP," "biochemical recurrence," "BCR," "biochemical relapse." Eleven studies, with a total of 1383 patients, were included in our meta-analysis. Of all the variables, only Gleason score (GS) ≥7 (odds ratio [OR]: 3.82; 95% confidence interval [CI]: 2.60-5.64) and pathological tumor (pT) stage ≥3a (OR: 1.82; 95% CI: 1.36-2.42) were positively correlated with BCR. However, SRT combined with androgen deprivation therapy (ADT) (OR: 0.63; 95% CI: 0.44-0.90) and radiation therapy (RT) dose ≥64 Gy (OR: 0.35; 95% CI: 0.19-0.64) were negatively correlated with BCR. Perineural invasion (OR: 2.64; 95% CI: 1.11-6.26), preoperative prostate-specific antigen (PSA) ≥10 ng ml-1 (OR: 1.36; 95% CI: 0.94-1.96), positive surgical margin (OR: 0.92; 95% CI: 0.7-1.19), and seminal vesicle involvement (SVI) (OR: 1.09; 95% CI: 0.83-1.43) had no effect on BCR. Our meta-analysis indicated that pT stage, GS, RT dose, and SRT combined with ADT may influence BCR, while preoperative PSA, surgical margin, perineural invasion, and SVI have only a weak effect on BCR.

Solitary recurrence of castration-resistant prostate cancer with low or undetectable levels of prostate specific antigen salvaged with local ablative radiation therapy: A case report

Prostate cancer recurrences are usually first detected by increased levels of prostate specific antigen (PSA), and systemic therapy is often initiated if distant metastasis is confirmed. However, low or nearly undetectable levels of PSA in the modern era of ultrasensitive PSA assay may be difficult to interpret in patients with a history of prostate cancer. Deciding whether to initiate additional systemic therapy in limited indolent metastatic disease while balancing the quality of life of the patient and ensuring the oncologic control of the disease may be challenging. In the present study, the case of a biopsy-confirmed solitary spine recurrence of prostate cancer with nearly undetectable but persistent levels of PSA (0.05 ng/ml) is reported. Treatment of the recurrence with local ablative radiotherapy improved the pain experienced by the patient, and reduced his levels of PSA to undetectable limits (<0.05 ng/ml). Repeated imaging analysis, PSA assay and clinical assessment demonstrated durable control of the disease without the requirement for additional systemic treatments. The present case highlighted the importance of initiating appropriate work-up according to the clinical scenario. Local treatment for solitary or oligometastatic recurrence of prostate cancer may enhance the effectiveness of current therapeutic strategies and benefit certain patients.

Adverse pathology and undetectable ultrasensitive prostate-specific antigen after radical prostatectomy: is adjuvant radiation warranted?

OBJECTIVES

To determine if men with adverse pathology but undetectable ultrasensitive (<0.01 ng/mL) PSA are at high-risk for biochemical recurrence (BCR), or if there is a subset of patients at low-risk for whom the benefit of adjuvant radiation therapy might be limited.

PATIENTS AND METHODS

We evaluated 411 patients treated with RP from 2001 to 2013 without adjuvant radiation who had an undetectable (<0.01 ng/mL) PSA level after RP but with adverse pathology [positive surgical margins (PSMs), extraprostatic extension (EPE), and/or seminal vesicle invasion (SVI)]. Multivariable Cox regression analyses tested the relationship between pathological characteristics and BCR to identify groups of men at highest risk of early BCR.

RESULTS

On multivariable analysis, only pathological Gleason 7 (4 + 3), Gleason ≥8, and SVI independently predicted BCR (P = 0.019, P < 0.001, and P = 0.001, respectively), although on two-way analysis men with Gleason 7 (4 + 3) did not have significantly higher rates of BCR compared with patients with Gleason ≤6 (log-rank, P = 0.074). Men with either Gleason ≥8 (with PSMs or EPE) or SVI (15% of the cohort) defined a high-risk group vs men without these characteristics (3-year BCR risk of 50.4% vs 11.9%, log-rank, P < 0.001).

CONCLUSIONS

Among men with adverse pathology but an undetectable (<0.01 ng/mL) PSA level after RP, the benefits of adjuvant radiation are probably limited except for men with Gleason 8-10 (with PSMs or EPE) or SVI who are at high-risk of early BCR.

The use of early postoperative prostate-specific antigen to stratify risk in patients with positive surgical margins after radical prostatectomy

BACKGROUND

It is well recognized that the presence of positive surgical margins (PSM) after radical prostatectomy (RP) adversely affects cancer specific outcomes and recent evidence from randomized trials supports the use of adjuvant radiotherapy in these cases. However, not all of the patients with PSM develop disease recurrence and the policy of adjuvant radiation could result in considerable over-treatment. We investigated the ability of early postoperative prostate specific antigen (PSA) and PSA decline rates to stratify the risk of disease progression during the first weeks after the surgery thereby allowing adequate time for planning eventual adjuvant therapy.

METHODS

We studied 116 consecutive patients with the finding of PSM after RP for localized prostate cancer between 2001 and 2012. No patients were treated with radiation or hormonal therapy. An intensive postoperative PSA monitoring using ultrasensitive assay started first at day 14 after the surgery, then at day 30, 60, 90 and 180, and subsequently in 3 monthly intervals. Biochemical recurrence (BCR) presented the failure of surgical treatment and it was defined as PSA ≥0.2 ng/ml. The ability of PSA decline parameters to predict BCR was assessed using Cox regression model and area under the curve (AUC) calculation.

RESULTS

Overall 55 (47%) patients experienced BCR during median follow-up of 31.4 months (range 6-69). Preoperative PSA, pathologic Gleason sum and pathologic grade failed to reveal any association with observation of BCR. Postoperative PSA levels achieved significant predictive accuracy already on day 30 (AUC 0.74). PSA >0.073 ng/ml at day 30 increased significantly the risk of BCR (HR 4.35, p < 0.001). Predictive accuracy was significantly exceeded on day 60 (AUC 0.84; p < 0.001), while further enhancements on day 90 (AUC 0.84) and 180 (AUC 0.91) were not significant.

CONCLUSIONS

The level of ultrasensitive PSA yields valuable information about the prostatectomy outcome already at the first month after the surgery and should aid risk stratification in patients with PSM. Patients not likely to experience subsequent disease progression may be spared the toxicity of immediate adjuvant radiotherapy.

A critical review of the analytical approaches for circulating tumor biomarker kinetics during treatment

Changes in serum tumor biomarkers may indicate treatment efficacy. Traditional tumor markers may soon be replaced by novel serum biomarkers, such as circulating tumor cells (CTCs) or circulating tumor nucleic acids. Given their promising predictive values, studies of their kinetics are warranted. Many methodologies meant to assess kinetics of traditional marker kinetics during anticancer treatment have been reported. Here, we review the methodologies, the advantages and the limitations of the analytical approaches reported in the literature. Strategies based on a single time point were first used (baseline value, normalization, nadir, threshold at a time t), followed by approaches based on two or more time points [half-life (HL), percentage decrease, time-to-events…]. Heterogeneities in methodologies and lack of consideration of inter- and intra-individual variability may account for the inconsistencies and the poor utility in routine. More recently, strategies based on a population kinetics approach and mathematical modeling have been reported. The identification of equations describing individual kinetic profiles of biomarkers may be an alternative strategy despite its complexity and higher number of necessary measurements. Validation studies are required. Efforts should be made to standardize biomarker kinetic analysis methodologies to ensure the optimized development of novel serum biomarkers and avoid the pitfalls of traditional markers.

Salvage radiotherapy after radical prostatectomy: prediction of biochemical outcomes

Introduction

A significant proportion of patients undergoing salvage radiotherapy (RT) for biochemical recurrence (BCR) following radical prostatectomy (RP) may again experience BCR after salvage RT. Thus, we evaluated the clinical significances of different parameters on the biochemical outcome of RT in salvage setting.

Methods

We reviewed the records of 212 patients who underwent salvage RT between November 2003 and December 2012 for BCR following primary RP. BCR-free survivals after salvage RT were estimated using the Kaplan–Meier method. Cox proportional hazard regression models were used to evaluate the impacts of clinicopathologic parameters on BCR following salvage RT.

Results

The overall median follow-up duration was 63.5 months. The BCR-free survival rate after salvage RT was 58.2% at 5 years. Multivariate analysis showed that a pre-RT prostate-specific antigen (PSA) level of ≤0.5 ng/mL, a pre-RT PSA doubling time (PSADT) of >4.5 months, concomitant androgen deprivation therapy (ADT) with salvage RT, and a positive surgical margin were independent predictors of favorable biochemical outcomes after salvage RT (hazard ratios [HR] = 3.012, 1.132, 2.000, and 1.805, respectively, p = less than 0.001, 0.013, 0.005, and 0.036, respectively). In the early (pre-RT PSA ≤0.5 ng/mL) salvage RT setting, concomitant ADT administration was also shown to be significantly associated with higher risk of BCR-free survival following salvage RT (HR = 2.611, p = 0.038).

Conclusion

Lower pre-RT PSA value, longer PSADT before salvage RT, concomitant ADT administration, and a positive surgical margin were significant predictors of favorable biochemical outcomes following salvage RT performed for BCR after primary RP.

Prostate-specific antigen measured 3 months after radical prostatectomy as a new predictor of biochemical recurrence

BACKGROUND

This study was undertaken to investigate if the prostate-specific antigen (PSA) level measured 3 months after radical prostatectomy (RP) is a predictor of biochemical recurrence (BCR)-free survival.

METHODS

We retrospectively reviewed the clinicopathologic data of 174 patients with a follow-up of at least 3 years after RP for clinically localized prostate cancer. None of the patients received neoadjuvant/adjuvant therapy. Subjects were categorized according to PSA level 3 months after RP (3M-PSA): <0.010 ng/mL (group 1; n = 119) or 0.010-0.100 ng/mL (group 2; n = 55). BCR was defined as two consecutive rises in PSA level ≥0.2 ng/mL.

RESULTS

At a median follow-up of 69.5 months (range 36-113 months), 32 (18.4 %) patients experienced BCR. The median time to BCR was 16 months (range 4-98 months) after RP. The 5-year BCR-free survival rate was 92.6 and 57.4 % in groups 1 and 2, respectively. Patients in group 1 had a significantly higher BCR-free survival rate than those in group 2 (log-rank P < 0.001). According to the Cox proportional hazards model, patients with a 3M-PSA level of <0.010 ng/mL were at lower risk for BCR (P < 0.001), along with pathologic Gleason sum 6 (P = 0.028). PSA nadir level after RP was also a risk factor for BCR (log-rank P < 0.001). Area under the receiver operating characteristic curve for 3M-PSA to predict BCR was almost equivalent to that for the PSA nadir level (0.855 vs. 0.849).

CONCLUSIONS

3M-PSA is an independent predictor of BCR-free survival. Our findings might be used for a risk-adjusted follow-up protocol.

NADiA ProsVue prostate-specific antigen slope is an independent prognostic marker for identifying men at reduced risk of clinical recurrence of prostate cancer after radical prostatectomy

OBJECTIVE

To validate the hypothesis that men displaying serum prostate-specific antigen (PSA) slopes ≤ 2.0 pg/mL/mo after prostatectomy, measured using a new immuno-polymerase chain reaction diagnostic test (NADiA ProsVue), have a reduced risk of clinical recurrence as determined by positive biopsy, imaging findings, or death from prostate cancer.

MATERIALS AND METHODS

From 4 clinical sites, we selected a cohort of 304 men who had been followed up for 17.6 years after prostatectomy for clinical recurrence. We assessed the prognostic value of a PSA slope cutpoint of 2.0 pg/mL/mo against established risk factors to identify men at low risk of clinical recurrence using uni- and multivariate Cox proportional hazards regression and Kaplan-Meier analyses.

RESULTS

The univariate hazard ratio of a PSA slope >2.0 pg/mL/mo was 18.3 (95% confidence interval 10.6-31.8) compared with a slope ≤ 2.0 pg/mL/mo (P <.0001). The median disease-free survival interval was 4.8 years vs >10 years in the 2 groups (P <.0001). The multivariate hazard ratio for PSA slope with the covariates of preprostatectomy PSA, pathologic stage, and Gleason score was 9.8 (95% confidence interval 5.4-17.8), an 89.8% risk reduction for men with PSA slopes ≤ 2.0 pg/mL/mo (P <.0001). The Gleason score (<7 vs ≥ 7) was the only other significant predictor (hazard ratio 5.4, 95% confidence interval 2.1-13.8, P = .0004).

CONCLUSION

Clinical recurrence after radical prostatectomy is difficult to predict using established risk factors. We have demonstrated that a NADiA ProsVue PSA slope of ≤ 2.0 pg/mL/mo after prostatectomy is prognostic for a reduced risk of prostate cancer recurrence and adds predictive power to the established risk factors.

Parameters derived from the postoperative decline in ultrasensitive PSA improve the prediction of radical prostatectomy outcome

PURPOSE

Contemporary tools estimating increased risk of prostate cancer (PCa) relapse after radical prostatectomy (RP) are far from perfect and there has been an intensive search for additional predictive variables. We aimed to explore whether the parameters of postoperative ultrasensitive prostate-specific antigen (PSA) decline provide additional information for predicting PCa progression.

METHODS

A total of 319 consecutive men, with at least 2 years of follow-up after RP for clinically localized PCa were subjected to this study. Intensive postoperative measurements of ultrasensitive PSA resulted in total of 4028 PSA values available for statistical evaluation. Biochemical recurrence (BCR) was defined as PSA ≥0.2 ng/ml. The accuracy of predictive models was quantified with the area under the curve.

RESULTS

Over a median follow-up of 43 months (24-99 months), 107 patients (34%) experienced BCR after RP. In patients with BCR, significantly higher values of PSA nadir (p < 0.001) and a decreased time interval from surgery to reach PSA nadir (p < 0.001) were observed. A multivariable Cox regression model confirmed that PSA nadir >0.01 ng/ml (HR 6.01, 95% CI: 3.89-9.52) and time to PSA nadir <3 months (HR 2.86, 95% CI: 1.74-5.01) were independent predictors of BCR. The inclusion of PSA nadir and the time to PSA nadir into the model resulted in improvement of predictive accuracy by 16% over the model designed on the basis of established parameters.

CONCLUSIONS

Our results demonstrate that the level of PSA nadir and the time to PSA nadir determined by ultrasensitive assay significantly improve the identification of patients who are at high risk of disease recurrence after RP.

Nucleic Acid Detection Immunoassay for Prostate-Specific Antigen Based on Immuno-PCR Methodology

BACKGROUND

Serum prostate-specific antigen (PSA) concentrations after radical prostatectomy typically become undetectable with the use of current immunometric assay methods. Despite modern surgical techniques, 15%–30% of prostate cancer patients undergoing radical prostatectomy develop a biochemical recurrence during follow-up. Unfortunately, poor analytical sensitivity of standard PSA assays delays biochemical recurrence detection, and because of day-to-day assay imprecision ultrasensitive PSA assays cannot assess PSA kinetics. We developed an immuno-PCR assay for total PSA that has a limit of quantification &gt;10 times lower than current ultrasensitive assays.

METHODS

The 2-site immunometric assay for total PSA employed 2 monoclonal antibodies, one conjugated to a double-stranded DNA label and the other bound to paramagnetic microparticles. After several washing steps, quantification cycles were determined and values were converted to PSA concentrations. We characterized analytical performance and compared accuracy with a commercially available total PSA assay.

RESULTS

The limit of quantification was 0.65 ng/L and the assay was linear in the range of 0.25–152.0 ng/L. Total imprecision estimates at PSA concentrations of 3.8, 24.1, and 69.1 ng/L were &lt;15.2%, &lt;9.4%, and &lt;10.6%, respectively. Recovery of supplemented PSA ranged from 87.5% to 119.2% (mean 100.3%). Dilution recovery ranged from 96.4% to 115.3% (mean 102.3%). There was no high-dose hook effect up to 50 000 ng/L of PSA. Comparison with the commercial PSA assay showed a regression slope of 1.06 and a correlation coefficient of 0.996.

CONCLUSIONS

The analytical characteristics of the assay support the use of this assay for the accurate and precise measurement of serum PSA, even at sub–nanogram-per-liter concentrations.

Postprostatectomy radiation therapy: an evidence-based review

While the majority of men with localized prostate cancer who undergo a radical prostatectomy will remain disease free, men with certain clinical and pathological features are known to be at an increased risk for developing a biochemical recurrence and, ultimately, distant metastatic disease. The optimal management of these patients continues to be a source of controversy. To date, three randomized Phase III trials have demonstrated that adjuvant radiation therapy (ART) for patients with certain adverse pathological features results in an improvement in several clinically-relevant end points, including biochemical recurrence-free survival and overall survival. Despite the evidence from these trials showing a benefit for ART, many believe that ART results in overtreatment and unwarranted treatment morbidity for a significant number of patients. Many physicians, therefore, instead advocate for close observation followed by early salvage radiation therapy (SRT) at the time of a biochemical recurrence. The purpose of this review is to evaluate the evidence for and to distinguish between ART and early SRT. We will also highlight current and future areas of research for this patient population, including radiation treatment dose escalation, hypofractionation and androgen deprivation therapy. We will also discuss the cost–effectiveness of ART and early SRT.

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.

Clinical evaluation of a novel method for the measurement of prostate-specific antigen, AccuPSA(TM) , as a predictor of 5-year biochemical recurrence-free survival after radical prostatectomy: results of a pilot study

Study Type - Diagnostic (validating cohort) Level of Evidence 1b What's known on the subject? and What does the study add? Nadir Ultrasensitive PSA levels has some value for predicting BCR following RD. AccuPSA assays lower limit of PSA quantification of <0.01 pg/ml greatly enhances sensitivity and specificity of nadir PSA to predict BCR following RP. Our pilot study shows an AccuPSA of 3 pg/ml has a sensitory and specificity of 100% and 75% respectively for predicting 5 year BCR following RP. OBJECTIVES • To conduct a proof of concept study to evaluate a novel digital single molecule immunoassay (AccuPSA(TM) ) that detects prostate-specific antigen (PSA) a thousandfold more sensitively than current PSA detection methods. • To determine the ability of the AccuPSA(TM) assay to predict 5-year biochemical recurrence (BCR)-free survival after radical prostatectomy (RP). PATIENTS AND METHODS • A total of 31 frozen serum specimens were obtained from specimen logs maintained at New York University Langone Medical Center and the Johns Hopkins University School of Medicine on men who had undergone RP. Those men without evidence of BCR had a minimum of 5 years' PSA follow-up. • In all cases, preoperative and pathological information were available, as was a serum specimen 3-6 months after RP, with a PSA level of <0.1 ng/mL measured by conventional PSA methods at the time of serum collection. • Specimens were tested using the AccuPSA(TM) method. • A Cox proportional hazard model and Kaplan-Meier analysis were used to determine whether AccuPSA(TM) predicted the risk of BCR. RESULTS • Overall, 11/31 (35.5%) men developed BCR. • Mean AccuPSA(TM) nadir levels were significantly different (P < 0.001) between the non-BCR group (2.27 pg/mL) and the BCR group (46.99 pg/mL). • Using a multivariate Cox proportional hazard model, AccuPSA(TM) nadir level was a significant predictor of BCR-free survival (P < 0.01). • Kaplan-Meier analysis of up to 5 years follow-up showed that 100% of men with AccuPSA(TM) nadir values <3 pg/mL did not develop BCR, whereas 62.5% of men with values >3 pg/mL developed BCR (P= 0.00024). • The sensitivity, specificity, positive predictive value and negative predictive value of the AccuPSA(TM) method was 100%, 75%, 69% and 100%, respectively. CONCLUSIONS • AccuPSA(TM) assay predicts 5-year BCR- free survival after RP. • Identifying a reliable predictor of BCR soon after RP has important implications for frequency of PSA testing, selection of candidates for adjuvant therapy, and reassuring a large subset of men that they are not at risk of recurrence. • Larger studies are needed to validate these findings.