3D MR-spectroscopic imaging assessment of metabolic activity in the prostate during the PSA "bounce" following 125iodine brachytherapy

PSA bounce: understanding temporal fluctuations in prostate cancer after external radiotherapy

PURPOSE

Prostate-specific antigen (PSA) bounce is a transient elevation in PSA levels commonly observed after radiotherapy. This study aims to investigate the characteristics, timing, and clinical implications of PSA bounce (PSA-B) in prostate cancer patients treated with external beam radiotherapy (EBRT), exploring potential causes and its relevance in patient management.

MATERIALS AND METHODS

Between 2013 and 2019, 629 patients with localized prostate cancer were treated with EBRT. After excluding patients with fewer than four PSA measurements or follow-up under 3 years (n = 184), 445 patients were analyzed. The median follow-up duration was 5.9 years (36-105 months). PSA-B was defined as a rise of ≥ 0.2 ng/mL above the nadir, followed by a subsequent decline to or below the nadir. PSA relapse was defined according to Phoenix definition.

RESULTS

A total of 64 patients (14.4%) experienced PSA-B at a median of 31 months (6-68 months). Univariable analysis identified age (p < 0.001), risk group (p < 0.001), perineural invasion (p < 0.007), radiotherapy duration (p < 0.001), and the absence of concurrent hormonal therapy (p < 0.001) as independent predictors of PSA-B. Multivariable analysis confirmed age and high-risk group as significant factors. PSA relapse occurred in 10.3% of cases, with only one patient who experienced both PSA-B and relapse.

CONCLUSIONS

PSA-B is a common phenomenon in localized prostate cancer patients post-EBRT. Factors such as age, risk group, perineural invasion, radiotherapy duration, and hormonal treatment use are associated with PSA-B occurrence. Understanding its mechanisms is crucial for optimizing prostate cancer management.

Imaging Biomarkers in Prostate Stereotactic Body Radiotherapy: A Review and Clinical Trial Protocol

Advances in imaging have changed prostate radiotherapy through improved biochemical control from focal boost and improved detection of recurrence. These advances are reviewed in the context of prostate stereotactic body radiation therapy (SBRT) and the ARGOS/CLIMBER trial protocol. ARGOS/CLIMBER will evaluate 1) the safety and feasibility of SBRT with focal boost guided by multiparametric MRI (mpMRI) and ¹⁸F-PSMA-1007 PET and 2) imaging and laboratory biomarkers for response to SBRT. To date, response to prostate SBRT is most commonly evaluated using the Phoenix Criteria for biochemical failure. The drawbacks of this approach include lack of lesion identification, a high false-positive rate, and delay in identifying treatment failure. Patients in ARGOS/CLIMBER will receive dynamic ¹⁸F-PSMA-1007 PET and mpMRI prior to SBRT for treatment planning and at 6 and 24 months after SBRT to assess response. Imaging findings will be correlated with prostate-specific antigen (PSA) and biopsy results, with the goal of early, non-invasive, and accurate identification of treatment failure.

Characteristics of PSA Bounce after Radiotherapy for Prostate Cancer: A Meta-Analysis

The rate and characteristics of prostate-specific antigen (PSA) bounce post-radiotherapy remain unclear. To address this issue, we performed a meta-analysis. Reports of PSA bounce post-radiotherapy with a cutoff of 0.2 ng/mL were searched by using Medline and Web of Science. The primary endpoint was the occurrence rate, and the secondary endpoints were bounce characteristics such as amplitude, time to occurrence, nadir value, and time to nadir. Radiotherapy modality, age, risk classification, androgen deprivation therapy, and the follow-up period were extracted as clinical variables. Meta-analysis and univariate meta-regression were performed with random-effect modeling. Among 290 search-positive studies, 50 reports including 26,258 patients were identified. The rate of bounce was 31%; amplitude was 1.3 ng/mL; time to occurrence was 18 months; nadir value was 0.5 ng/mL; time to nadir was 33 months. Univariate meta-regression analysis showed that radiotherapy modality (29.7%), age (20.2%), and risk classification (12.2%) were the major causes of heterogeneity in the rate of bounce. This is the first meta-analysis of PSA bounce post-radiotherapy. The results are useful for post-radiotherapy surveillance of prostate cancer patients.

Diagnostic performance of imaging techniques for detecting of local recurrence after prostate brachytherapy

PURPOSE

The purpose of this study was to evaluate MRI and fluorocholine PET/CT diagnostic performances for the detection of local recurrence following prostate brachytherapy for localised prostate cancer.

MATERIAL AND METHODS

In this single-centre study, we retrospectively reviewed data from 21 patients treated by brachytherapy for localised prostate cancer and diagnosed with biochemical recurrence according to Phoenix Criteria, who underwent MRI and fluorocholine PET/CT. We included patients with local relapse suspicion according to imaging exams, with biopsy for the final assessment of local recurrence. Patient analysis data were supplemented by segment analysis using an 8-segment model.

RESULTS

The fluorocholine PET/CT was positive for 81% and negative for 19% of patients. The sensitivity and specificity were 92% and 33% with diagnosis accuracy of 67%. The MRI was positive for 57% and negative for 43% of patients. The sensitivity and specificity were 67% and 56% with diagnosis accuracy of 62%. There was no statistically significant difference between fluorocholine PET/CT and MRI accuracy (P=0.63). On a segment-based analysis, the sensitivity and specificity were 44% and 82% for fluorocholine PET/CT with diagnosis accuracy of 78%. For MRI, specificity was 91% diagnosis accuracy was 82%.

CONCLUSION

Both MRI and fluorocholine PET/CT permit to highlight local recurrence sites after prostate brachytherapy. Confirmation biopsies are, however, necessary since this accuracy is insufficient.

Good prognosis following a PSA bounce after high dose rate brachytherapy and external radiotherapy in prostate cancer

BACKGROUND

PSA kinetics after curative radiotherapy for prostate cancer is an important part of the posttreatment evaluation. We analysed PSA bounce occurrence after combined high dose rate brachytherapy (HDR-BT) and external radiotherapy (ERT).

MATERIAL & METHODS

We analysed 623 patients treated from 1995 to 2008. The median age was 66 years (47-79). The median initial PSA was 12 ng/ml (0.1-224). Neoadjuvant endocrine therapy was given to 429 patients. ERT was given with 2 Gy fractions to 50 Gy and HDR-BT in two 10 Gy fractions. The median follow-up was 11 years (range 2-266 months). PSA bounce was defined as a temporary rise in PSA >0.2 ng/ml. PSA failure was defined according to the Phoenix definition.

RESULTS

PSA bounce occurred in 159 patients (26%), where 56 patients had a bounce amplitude >2 ng/ml and 31 patients had multiple bounces. Median time to bounce peak was 15 (3-103) months with a median bounce value of 1.5 (0.3-12)ng/ml. Younger age and lower Gleason scores were associated with PSA bounce. In a Cox regression analysis with PSA bounce as a time-dependent covariate and adjusted for other prognostic factors, PSA bounce was associated with a lower risk for PSA failure (HR = 0.42; 95% confidence interval 0.26-0.70).

CONCLUSION

PSA bounce after HDR-BT combined with ERT is common and associated with a good prognosis. As the relapse risk after an early bounce is very low, the findings should alert clinicians not to initiate salvage treatment too early. Research in prospective identification of PSA bounce is clinically relevant.

Prostate-Specific Antigen (PSA) Bounce After Dose-Escalated External Beam Radiation Therapy Is an Independent Predictor of PSA Recurrence, Metastasis, and Survival in Prostate Adenocarcinoma Patients

PURPOSE

To evaluate the difference in prostate-specific antigen (PSA) recurrence-free, distant metastasis-free, overall, and cancer-specific survival between PSA bounce (PSA-B) and non-bounce patients treated with dose-escalated external beam radiation therapy (DE-EBRT).

METHODS AND MATERIALS

During 1990-2010, 1898 prostate adenocarcinoma patients were treated with DE-EBRT to ≥75 Gy with ≥5 years follow-up. Patients receiving neoadjuvant/concurrent androgen-deprivation therapy (n=1035) or with fewer than 4 PSA values obtained 6 months or more after post-EBRT completion (n=87) were excluded. The evaluable 776 patients were treated (median, 81.0 Gy). Prostate-specific antigen bounce was defined as a ≥0.2-ng/mL increase above the interval PSA nadir, followed by a decrease to nadir or below. Prostate-specific antigen relapse was defined as post-radiation therapy PSA nadir + 2 ng/mL. Median follow-up was 9.2 years (interquartile range, 6.9-11.3 years).

RESULTS

One hundred twenty-three patients (15.9%) experienced PSA-B after DE-EBRT at a median of 24.6 months (interquartile range, 16.1-38.5 months). On multivariate analysis, younger age (P=.001), lower Gleason score (P=.0003), and higher radiation therapy dose (P=.0002) independently predicted PSA-B. Prostate-specific antigen bounce was independently associated with decreased risk for PSA relapse (hazard ratio [HR] 0.53; 95% confidence interval [CI] 0.33-0.85; P=.008), distant metastatic disease (HR 0.34; 95% CI 0.12-0.94; P=.04), and all-cause mortality (HR 0.53; 95% CI 0.29-0.96; P=.04) on multivariate Cox analysis. Because all 50 prostate cancer-specific deaths in patients without PSA-B were in the non-bounce cohort, competing-risks analysis was not applicable. A nonparametric competing-risks test demonstrated that patients with PSA-B had superior cancer-specific survival compared with patients without PSA-B (P=.004).

CONCLUSIONS

Patients treated with dose-escalated radiation therapy for prostate adenocarcinoma who experience posttreatment PSA-B have improved PSA recurrence-free survival, distant metastasis-free survival, overall survival, and cancer-specific survival outcomes.

Tumour and immune cell dynamics explain the PSA bounce after prostate cancer brachytherapy

BACKGROUND

Interstitial brachytherapy for localised prostate cancer may be followed by transient increases in prostate-specific antigen (PSA) that resolve without therapy. Such PSA bounces may be associated with an improved outcome but often cause alarm in the patient and physician, and have defied explanation.

METHODS

We developed a mathematical model to capture the interactions between the tumour, radiation and anti-tumour immune response. The model was fitted to data from a large cohort of patients treated exclusively with interstitial brachytherapy. Immunohistological analysis for T-cell infiltration within the same tumours was also performed.

RESULTS

Our minimal model captures well the dynamics of the tumour after therapy, and suggests that a strong anti-tumour immune response coupled with the therapeutic effect of radiation on the tumour is responsible for the PSA bounce. Patients who experience a PSA bounce had a higher density of CD3 and CD8 cells within the tumour that likely contribute to the PSA bounce and the overall better outcomes observed.

CONCLUSIONS

Our observations provide a novel and unifying explanation for the PSA bounce in patients with early prostate cancer and also have implications for the use of immune-based therapies in such patients to improve outcomes.

Metabolic Imaging in Humans

Metabolic imaging enhances understanding of disease metabolisms and holds great potential as a measurement tool for evaluating disease prognosis and treatment effectiveness. Advancement of techniques, such as magnetic resonance spectroscopy, positron emission tomography, and mass spectrometry, allows for improved accuracy for quantification of metabolites and present unique possibilities for use in clinic. This article reviews and discusses literature reports of metabolic imaging in humans published since 2010 according to disease type, including cancer, degenerative disorders, psychiatric disorders, and others, as well as the current application of the various related techniques.

Stratification of the aggressiveness of prostate cancer using pre-biopsy multiparametric MRI (mpMRI)

Risk stratification, based on the Gleason score (GS) of a prostate biopsy, is an important decision-making tool in prostate cancer management. As low-grade disease may not need active intervention, the ability to identify aggressive cancers on imaging could limit the need for prostate biopsies. We assessed the ability of multiparametric MRI (mpMRI) in pre-biopsy risk stratification of men with prostate cancer. One hundred and twenty men suspected to have prostate cancer underwent mpMRI (diffusion MRI and MR spectroscopic imaging) prior to biopsy. Twenty-six had cancer and were stratified into three groups based on GS: low grade (GS ≤ 6), intermediate grade (GS = 7) and high grade (GS ≥ 8). A total of 910 regions of interest (ROIs) from the peripheral zone (PZ, range 25-45) were analyzed from these 26 patients. The metabolite ratio [citrate/(choline + creatine)] and apparent diffusion coefficient (ADC) of voxels were calculated for the PZ regions corresponding to the biopsy cores and compared with histology. The median metabolite ratios for low-grade, intermediate-grade and high-grade cancer were 0.29 (range: 0.16, 0.61), 0.17 (range: 0.13, 0.32) and 0.13 (range: 0.05, 0.23), respectively (p = 0.004). The corresponding mean ADCs (×10(-3) mm(2) /s) for low-grade, intermediate-grade and high-grade cancer were 0.99 ± 0.08, 0.86 ± 0.11 and 0.69 ± 0.12, respectively (p < 0.0001). The combined ADC and metabolite ratio model showed strong discriminatory ability to differentiate subjects with GS ≤ 6 from subjects with GS ≥ 7 with an area under the curve of 94%. These data indicate that pre-biopsy mpMRI may stratify PCa aggressiveness noninvasively. As the recent literature data suggest that men with GS ≤ 6 cancer may not need radical therapy, our data may help limit the need for biopsy and allow informed decision making for clinical intervention. Copyright © 2015 John Wiley & Sons, Ltd.

Distinguishing prostate-specific antigen bounces from biochemical failure after low-dose-rate prostate brachytherapy

Purpose

The purpose of this study was to characterize benign prostate-specific antigen (PSA) bounces of at least 2.0 ng/mL and biochemical failure as defined by the Phoenix definition after prostate brachytherapy at our institution, and to investigate distinguishing features between three outcome groups: patients experiencing a benign PSA bounce, biochemical failure, or neither.

Material and methods

Five hundred and thirty consecutive men treated with low-dose-rate brachytherapy with follow-up of at least 3 years were divided into outcome groups experiencing bounce, failure, or neither. A benign bounce was defined as a rise of at least 2.0 ng/mL over the pre-rise nadir followed by a decline to 0.5 ng/mL or below, without intervention. Patient and tumor characteristics, treatment variables, and PSA kinetics were analyzed between groups.

Results

Thirty-two (6.0%) men experienced benign bounces and 47 (8.9%) men experienced failure. Men experiencing a bounce were younger (p = 0.01), had a higher 6-month PSA level (p = 0.03), and took longer to reach a final nadir (p < 0.01). Compared to the failure group, men with bounce had a lower pre-treatment PSA level (p = 0.01) and experienced a rise of at least 2.0 ng/mL that occurred sooner after the implant (p < 0.01) with a faster PSA doubling time (p = 0.01). Only time to PSA rise independently differentiated between bounce and failure (p < 0.01), with a benign bounce not being seen after 36 months post-treatment. Prostate-specific antigen levels during a bounce reached levels as high as 12.6 ng/mL in this cohort, and in some cases took over 5 years to decline to below 0.5 ng/mL.

Conclusions

Although there is substantial overlap between the features of benign PSA bounces and failure, physicians may find it useful to evaluate the timing, absolute PSA level, initial response to treatment, and rate of rise when contemplating management for a PSA rise after low-dose-rate brachytherapy.

Interpreting a rising prostate-specific antigen after brachytherapy for prostate cancer

The aim of the present study was to review the English language literature on the topic of prostate-specific antigen bounce after brachytherapy and present a summary of the current knowledge. Although ultimately prostate-specific antigen is a reliable measure of success after prostate brachytherapy, it can be very misleading in the first 3 years because of the frequency with which temporary benign rises in prostate-specific antigen occur. We have reviewed the English language literature on the topic of prostate-specific antigen bounce under the following headings: prostate neoplasms, brachytherapy, biochemical definition of prostate-specific antigen failure, "benign prostate-specific antigen bounce" and "prostate-specific antigen spike". We included brachytherapy delivered as either low dose rate or high dose rate, and either as monotherapy or as a boost combined with external beam radiotherapy. A benign self-limited rise in prostate-specific antigen after prostate brachytherapy is seen in an average of 35% of patients, but increases in frequency with younger age. In patients aged less than 55 years, it is observed in up to 68%. Other factors, such as sexual activity, dose, prostate volume and the use of high dose rate versus low dose rate have been implicated in affecting the frequency of the benign bounce. Benign increases in prostate-specific antigen are frequent after prostate brachytherapy. It is important to recognize and correctly diagnose this phenomenon in order to avoid unnecessary salvage treatment.

Imaging techniques for local recurrence of prostate cancer: for whom, why and how?

Since there are salvage solutions, it is important to detect local recurrence of prostate cancer as early as possible. The first sign is "biochemical failure" in that the prostate specific antigen (PSA) concentration rises again. The definition of biochemical failure varies depending on the initial treatment: PSA greater than 0.2ng/mL after prostatectomy, nadir+2ng/mL after radiotherapy. There is no standardised definition of biochemical failure after cryotherapy, focused ultrasound, or brachytherapy. Magnetic resonance imaging (MRI) (particularly dynamic MRI) can detect local recurrence with good sensitivity. The role of spectroscopy is still under discussion. For the moment, ultrasound techniques are less effective than MRI.

Permanent 125I-seed prostate brachytherapy: early prostate specific antigen value as a predictor of PSA bounce occurrence

Purpose

To evaluate predictive factors for PSA bounce after ¹²⁵I permanent seed prostate brachytherapy and identify criteria that distinguish between benign bounces and biochemical relapses.

Materials and methods

Men treated with exclusive permanent ¹²⁵I seed brachytherapy from November 1999, with at least a 36 months follow-up were included. Bounce was defined as an increase ≥ 0.2 ng/ml above the nadir, followed by a spontaneous return to the nadir. Biochemical failure (BF) was defined using the criteria of the Phoenix conference: nadir +2 ng/ml.

Results

198 men were included. After a median follow-up of 63.9 months, 21 patients experienced a BF, and 35.9% had at least one bounce which occurred after a median period of 17 months after implantation (4-50). Bounce amplitude was 0.6 ng/ml (0.2-5.1), and duration was 13.6 months (4.0-44.9). In 12.5%, bounce magnitude exceeded the threshold defining BF. Age at the time of treatment and high PSA level assessed at 6 weeks were significantly correlated with bounce but not with BF. Bounce patients had a higher BF free survival than the others (100% versus 92%, p = 0,007). In case of PSA increase, PSA doubling time and velocity were not significantly different between bounce and BF patients. Bounces occurred significantly earlier than relapses and than nadir + 0.2 ng/ml in BF patients (17 vs 27.8 months, p < 0.0001).

Conclusion

High PSA value assessed 6 weeks after brachytherapy and young age were significantly associated to a higher risk of bounces but not to BF. Long delays between brachytherapy and PSA increase are more indicative of BF.

MR imaging of treated prostate cancer

Many management options are available to patients with newly diagnosed prostate cancer. Magnetic resonance (MR) imaging plays an important role in initial staging of prostate cancer, but it also aids in tumor detection when there is clinical or biochemical suspicion of residual or recurrent disease after treatment. The purpose of this review is to describe the normal appearances of the prostatic region after different kinds of treatment for prostate cancer and to discuss how these appearances differ from those of recurrent and residual disease. Several MR imaging techniques used in evaluating patients with prostate cancer are described, including conventional MR imaging sequences (mainly T1- and T2-weighted sequences), MR spectroscopic imaging, diffusion-weighted imaging, and dynamic contrast agent-enhanced MR imaging. Clinical considerations, together with the different approaches for interpreting serum prostate-specific antigen values in the posttreatment setting, are also presented. All forms of treatment alter the MR imaging features of the prostatic region to a greater or lesser extent, and it is important to be able to recognize expected posttreatment appearances and distinguish them from the features of recurrent or residual cancer to aid subsequent clinical management.

Early choline levels from 3-tesla MR spectroscopy after exclusive radiation therapy in patients with clinically localized prostate cancer are predictive of plasmatic levels of PSA at 1 year

PURPOSE

To investigate the time course response of prostate metabolism to irradiation using magnetic resonance spectroscopy (MRS) at 3-month intervals and its impact on biochemical control.

METHODS AND MATERIALS

Between January 2008 and April 2010, 24 patients with localized prostate cancer were prospectively enrolled in the Evaluation of the Response to Irradiation with MR Spectroscopy (ERIS) trial. All the patients had been treated with intensity-modulated radiation therapy with or without long-term adjuvant hormonal therapy (LTHT) and underwent 3-T MRS and prostate-specific antigen (PSA) assays at baseline and every 3 months thereafter up to 12 months.

RESULTS

After radiation, the mean normalized citrate level (citrate/water) decreased significantly over time, both in the peripheral zone (PZ) (p = 0.0034) and in the entire prostate (p = 0.0008), whereas no significant change was observed in mean normalized choline levels (choline/water) in the PZ (p = 0.84) and in the entire prostate (p = 0.95). At 6 months after radiation, the mean choline level was significantly lower in the PZ for patients with a PSA value of ≤0.5 ng/mL at 12 months (4.9 ± 1.7 vs. 7.1 ± 1.5, p = 0.0378). Similar results were observed at 12 months in the PZ (6.2 ± 2.3 vs. 11.4 ± 4.1, p = 0.0117 for choline level and 3.4 ± 0.7 vs. 16.1 ± 6.1, p = 0.0054 for citrate level) and also in the entire prostate (6.2 ± 1.9 vs. 10.4 ± 3.2, p = 0.014 for choline level and 3.0 ± 0.8 vs. 13.3 ± 4.7, p = 0.0054 for citrate level). For patients receiving LTHT, there was no correlation between choline or citrate levels and PSA value, either at baseline or at follow-up.

CONCLUSIONS

Low normalized choline in the PZ, 6 months after radiation, predicts which patients attained a PSA ≤0.5 ng/mL at 1 year. Further analyses with longer follow-up times are warranted to determine whether or not these new biomarkers can conclusively predict the early radiation response and the clinical outcome for patients with or without LTHT.

A decade in prostate cancer: from NMR to metabolomics

Over the past 30 years, continuous progress in the application of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance spectroscopic imaging (MRSI) to the detection, diagnosis and characterization of human prostate cancer has turned what began as scientific curiosity into a useful clinical option. In vivo MRSI technology has been integrated into the daily care of prostate cancer patients, and innovations in ex vivo methods have helped to establish NMR-based prostate cancer metabolomics. Metabolomic and multimodality imaging could be the future of the prostate cancer clinic--particularly given the rationale that more accurate interrogation of a disease as complex as human prostate cancer is most likely to be achieved through paradigms involving multiple, instead of single and isolated, parameters. The research and clinical results achieved through in vivo MRSI and ex vivo NMR investigations during the first 11 years of the 21st century illustrate areas where these technologies can be best translated into clinical practice.

Prostate specific antigen bounce is related to overall survival in prostate brachytherapy

PURPOSE

To investigate the association between prostate specific antigen (PSA) bounce and disease outcome after prostate brachytherapy.

METHODS AND MATERIALS

We analyzed 975 patients treated with (125)I implantation monotherapy between 1992 and 2006. All patients had tumor Stage ≤ 2c, Gleason score ≤ 7 prostate cancer, a minimum follow-up of 2 years with at least four PSA measurements, and no biochemical failure in the first 2 years. Median follow-up was 6 years. Bounce was defined as a PSA elevation of +0.2 ng/mL with subsequent decrease to previous nadir. We used the Phoenix +2 ng/mL definition for biochemical failure. Additional endpoints were disease-specific and overall survival. Multivariate Cox regression analysis was performed to adjust for potential confounding factors.

RESULTS

Bounce occurred in 32% of patients, with a median time to bounce of 1.6 years. More than 90% of bounces took place in the first 3 years after treatment and had disappeared within 2 years of onset. Ten-year freedom from biochemical failure, disease-specific survival, and overall survival rates were, respectively, 90%, 99%, and 88% for the bounce group and 70%, 93%, and 82% for the no-bounce group. Only 1 patient (0.3%) died of prostate cancer in the bounce group, compared with 40 patients (6.1%) in the no-bounce group. Adjusted for confounding, a 70% biochemical failure risk reduction was observed for patients experiencing a bounce (hazard ratio 0.31; 95% confidence interval 0.20-0.48).

CONCLUSIONS

A PSA bounce after prostate brachytherapy is strongly related to better outcome in terms of biochemical failure, disease-specific survival, and overall survival.