Association of Presalvage Radiotherapy PSA Levels After Prostatectomy With Outcomes of Long-term Antiandrogen Therapy in Men With Prostate Cancer

Drug Intensification in Future Postoperative Radiotherapy Practice in Biochemically-Relapsing Prostate Cancer Patients

Although salvage prostate bed radiotherapy is highly effective in biochemically-relapsing prostate cancer patients following prostatectomy, relapses remain frequent and improvements are needed. Randomized phase 3 trials have shown the benefit of adding androgen-depriving therapy to irradiation, but not all patients benefit from this combination. Preclinical studies have shown that novel agents targeting the androgen receptor, DNA repair, PI3K/AKT/mTOR pathways, or the hypoxic microenvironment may help increase the response to prostate bed irradiation while minimizing potential side effects. This perspective review focuses on the most relevant molecules that may have an impact when combined with salvage radiotherapy, and underlines the strategies that need to be developed to increase the efficacy of salvage post-prostatectomy radiotherapy in prostate cancer patients.

Post-Operative Radiotherapy in Prostate Cancer: Is It Time for a Belt and Braces Approach?

Approximately 30% of patients treated with radical prostatectomy (RP) for prostate cancers experience biochemical recurrence (BCR). Post-operative radiation therapy (RT) can be either offered immediately after the surgery in case of aggressive pathological features or proposed early if BCR occurs. Until recently, little data were available regarding the optimal RT timing, protocol, volumes to treat, and the benefit of adding androgen deprivation therapies to post-operative RT. In this review, we aim to pragmatically discuss current literature data on these points. Early salvage RT appears to be the optimal post-operative approach, improving oncological outcomes especially with low prostate-specific antigen (PSA) levels, as well as sparing several unnecessary adjuvant treatments. The standard RT dose is still 64–66 Gy to the prostate bed in conventional fractionation, but hypofractionation protocols are emerging pending on late toxicity data. Several scientific societies have published contouring atlases, even though they are heterogeneous and deserve future consensus. During salvage RT, the inclusion of pelvic lymph nodes is also controversial, but preliminary data show a possible benefit for PSA > 0.34 ng/ml at the cost of increased hematological side effects. Concomitant ADT and its duration are also discussed, possibly advantageous (at least in terms of metastasis-free survival) for PSA rates over 0.6 ng/ml, taking into account life expectancy and cardiovascular comorbidities. Intensified regimens, for instance, with new-generation hormone therapies, could further improve outcomes in carefully selected patients. Finally, recent advances in molecular imaging, as well as upcoming breakthroughs in genomics and artificial intelligence tools, could soon reshuffle the cards of the current therapeutic strategy.

Salvage therapy for prostate cancer after radical prostatectomy

More than 40% of men with intermediate-risk or high-risk prostate cancer will experience a biochemical recurrence after radical prostatectomy. Clinical guidelines for the management of these patients largely focus on the use of salvage radiotherapy with or without systemic therapy. However, not all patients with biochemical recurrence will go on to develop metastases or die from their disease. The optimal pre-salvage therapy investigational workup for patients who experience biochemical recurrence should, therefore, include novel techniques such as PET imaging and genomic analysis of radical prostatectomy specimen tissue, as well as consideration of more traditional clinical variables such as PSA value, PSA kinetics, Gleason score and pathological stage of disease. In patients without metastatic disease, the only known curative intervention is salvage radiotherapy but, given the therapeutic burden of this treatment, importance must be placed on accurate timing of treatment, radiation dose, fractionation and field size. Systemic therapy also has a role in the salvage setting, both concurrently with radiotherapy and as salvage monotherapy.

[Salvage radiotherapy after prostatectomy - what do do in case of elevated post operative PSA or macroscopic relapse?]

The management of the postoperative biological relapse of prostate cancer is most often based on salvage radiotherapy (RT) and a variable duration of hormone therapy (HT) in addition. The indications for RT±HT become more consensual for the adjuvant postoperative situation or in the event of a rising PSA level after a period where an undetectable PSA level was achieved. On the other hand, in the event of detectable PSA immediately postoperatively or in the event of a biological recurrence with macroscopic relapse in the prostate bed seen on conventional imaging assessment, the treatment options are still being evaluated. This article will describe these 2 situations and their current management but also will come through assessments with the contribution of modern imaging and new treatment options in terms of RT dose and RT±HT combination.

Should androgen deprivation therapy and other systemic treatments be used in men with prostate cancer and a rising PSA post-local treatments?

Biochemical recurrence is an evolving space in prostate cancer, with increasing multidisciplinary involvement. Androgen deprivation therapy has shown proof of its value in complementing salvage radiotherapy in high-risk biochemical relapsing patients; ongoing trials aim to further refine this treatment combination. As systemic treatments, and notably next-generation androgen receptor targeted agents, have moved towards early hormone-sensitive and non-metastatic stages, the prostate specific antigen (PSA)-relapse disease stage will be undoubtedly challenged by future evidence from such ongoing clinical trials. With the use of modern imaging and newer molecular technologies, including integration of tumoral genomic profiling and liquid biopsies in risk stratification, a path towards a precision oncology-focused approach will become a reality to guide in the future decisions for patients with a diagnosis of biochemical recurrence.

[Postoperative radiotherapy for prostate cancer: when to propose it? What is the place for androgen deprivation?]

PURPOSE

While there is no high-level evidence showing superiority of surgery over radiation treatment, radical prostatectomy is the most common treatment option for patients with localized, non-metastatic disease. Nearly 30% of all patients undergoing surgery will develop a biochemical recurrence in 10 years. In fact, more than 30% of contemporary patients treated with RP will harbor aggressive disease characteristics at final pathology.

MATERIAL AND MEHODS

We conducted a review of the literature evaluating the timing of radiotherapy and the place of androgen deprivation after prostatectomie totale.

RESULTS

Four trials randomizing adjuvant radiotherapy and surveillance found an advantage in biochemical relapse-free survival in favor of immediate irradiation after radical prostatectomy, called adjuvant. However, in these studies, more than 40% of patients in the arm without adjuvant radiotherapy did not relapse at 10 years of follow-up. More recently, the question of the optimal time of this post-operative, adjuvant RT or during biological relapse has arisen through three trials (RADICALS-RT, RAVES, GETUG-AFU 17). These trials did not show a benefit for adjuvant radiotherapy in terms of event-free survival, a PSA-based endpoint, while confirming the toxicities observed during irradiation immediately after surgery. The optimal duration of hormonal therapy when associated with post-prostatectomy radiation therapy remains controversial.

CONCLUSION

Early salvage radiotherapy is a new standard of treatment and adjuvant radiotherapy could be reserved for very selected patients. The role of hormone therapy is well defined in salvage situation, but its duration is still being studied.

A comprehensive assessment of 68Ga-PSMA-11 PET in biochemically recurrent prostate cancer: Results from a prospective multi-center study in 2005 patients

We prospectively investigated the performance of the prostate-specific membrane antigen (PSMA) ligand ⁶⁸Ga-PSMA-11 for detecting prostate adenocarcinoma in patients with elevated prostate-specific-antigen (PSA) after initial therapy. Methods: ⁶⁸Ga-PSMA-11 hybrid positron emission tomography (PET) was performed in 2005 patients at the time of biochemical recurrent prostate cancer (BCR) following either radical prostatectomy (RP) (50.8 %), definitive radiation therapy (RT) (19.7 %), or RP with post-operative RT (PORT) (29.6 %). Presence of prostate cancer was assessed qualitatively (detection rate = positivity rate) and quantitatively on a per-patient and per-region basis creating a disease burden estimate from presence or absence of local (prostate/prostate bed), nodal (N1: pelvis) and distant metastatic (M1: distant soft tissue and bone) disease. The primary study endpoint was the positive predictive value (PPV) of ⁶⁸Ga-PSMA-11 PET/CT confirmed by histopathology. Results: Following prostatectomy, the scan detection rate increased significantly with rising PSA levels (44.8 % at PSA < 0.25 to 96.2 % at PSA > 10 ng/mL; P < 0.001). The detection rate significantly increased with rising PSA levels in each individual region, overall disease burden, prior androgen deprivation, clinical T-stage, and Gleason grading from prostatectomy specimen (P < 0.001). Following RT, the detection rate for in-gland prostate recurrence was 64.0 % compared to 20.6 % prostate bed recurrences after RP and 13.3 % following PORT. PSMA-positive pelvic nodal disease was detected in 42.7 % following RP, in 40.8 % after PORT and 38.8 % after RT. In patients with histopathologic validation the PPV per-patient was 0.82 (146/179). The SUV_max of histologically proven true positive lesions was significantly higher than false positive lesions (median 11.0 (IQR 6.3 - 22.2) vs 5.1 (IQR 2.2 - 7.4) P < 0.001). Conclusion: We confirmed a high PPV of ⁶⁸Ga-PSMA-11 PET in BCR and the PSA level as the main predictor of scan positivity.

Outcomes and Prediction Models for Exclusive Prostate Bed Salvage Radiotherapy among Patients with Biochemical Recurrence after Radical Prostatectomy

BACKGROUND

The addition of androgen-deprivation therapy (ADT) or pelvic radiation to prostate bed salvage radiotherapy (SRT) has been debated for prostate cancer patients with biochemical recurrence (BCR) after radical prostatectomy. This study aimed to assess the outcomes and propose prediction models for exclusive prostate bed SRT.

METHODS

This is a prospective observational cohort study with patients who underwent SRT with a pre-SRT PSA < 1.5 ng/mL after radical prostatectomy. Patients were treated with 70-Gy SRT to the prostate bed exclusively. Kaplan-Meier survival analyses and Cox regression analyses were applied for depicting and predicting BCR-free survival, ADT-free survival, and metastasis-free survival (MFS). Regression-based coefficients were used to develop nomograms.

RESULTS

A total of 105 patients were included and 91 patients were eligible. The median follow-up period was 39 months. The 5-year BCR-free survival, ADT-free survival, and MFS were 37%, 50%, and 66%, respectively. Multivariable analysis showed that a pre-SRT PSA < 0.45 ng/mL was the only independent factor associated with longer BCR-free survival (p = 0.034), while a PSA-DT > 8 months had better ADT-free survival (p = 0.008). Patients with a PSA-DT > 8 months showed a 100% MFS and a 43% 5-year absolute benefit in MFS than a PSA-DT ≤ 8 months. All patients with a pre-SRT PSA < 0.45 ng/mL and PSA-DT > 8 months were free from subsequent ADT and any metastasis.

CONCLUSIONS

In patients with a PSA < 0.45 ng/mL and PSA-DT > 8 months for post-prostatectomy BCR, prostate bed SRT provided excellent outcomes without the need for concomitant ADT or pelvic radiotherapy.

The prognostic value, sensitivity, and specificity of multiparametric magnetic resonance imaging before salvage radiotherapy for prostate cancer

AIM

To determine the operational characteristics of pelvic magnetic resonance imaging (MRI) prior to salvage radiation therapy (SRT) for biochemically recurrent prostate cancer following radical prostatectomy.

METHODS AND MATERIALS

We reviewed the medical records of 386 patients who underwent MRI prior to SRT. We assessed associations of pre-SRT MRI findings with biochemical recurrence (BCR), distant metastasis (DM), prostate cancer-specific mortality (PCSM), and salvage androgen deprivation therapy (ADT) use following SRT. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI for detecting local recurrence were also calculated.

RESULTS

Pre-SRT MRI was positive for local recurrence in 216 patients (56%), indeterminate in 46 (12%), and negative in 124 (32%). On univariate analysis, BCR following SRT was significantly less likely for patients with positive (HR: 0.58, 95% CI: 0.42-0.8) or indeterminate (HR: 0.6: 0.36-1) MRI findings, compared to patients with negative imaging (p = 0.003). These associations remained significant on multivariate analysis (p < 0.05) and across pre-SRT PSA groups. For the entire cohort, the sensitivity of MRI for local recurrence was 61.0% (53.5-68.1%), specificity 60.0% (44.3-73.0%), PPV 86.1% (78.9-91.5%) and NPV 27.6% (19.0-37.5%). Sensitivity of MRI was better in men with higher pre-SRT PSA (80.0% for PSA > 1.0), and specificity was improved with lower pre-SRT PSA (73.9% for PSA 0.1-0.5).

CONCLUSIONS

Positive or indeterminate MRI findings prior to SRT were associated with improved biochemical control following SRT, across PSA levels. The sensitivity and specificity of MRI for local recurrence were 61% and 58.7%, respectively.

Integrating Prostate-specific Antigen Kinetics into Contemporary Predictive Nomograms of Salvage Radiotherapy After Radical Prostatectomy

BACKGROUND

Salvage radiotherapy (SRT) is an established treatment for men with biochemical recurrence following radical prostatectomy (RP). There are several risk factors associated with adverse outcomes; however, the value of postoperative prostate-specific antigen (PSA) kinetics is less clear in the ultrasensitive PSA era.

OBJECTIVE

To characterize the impact of PSA kinetics on outcomes following SRT and generate nomograms to aid in identifying patients with an increased risk of adverse clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

A multi-institutional analysis was conducted of 1005 patients with prostate cancer treated with SRT after RP, with a median follow-up of 5 years.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Variables examined include immediate postoperative PSA, postoperative PSA doubling time (DT), and pre-SRT PSA, in addition to previously identified predictive factors. Multivariable survival analyses were completed using Fine-Gray competing risk regression. Rates of biochemical failure (BF), distant metastasis (DM), and prostate cancer-specific mortality (PCSM) were estimated by the cumulative incidence method. Nomograms were generated from multivariable competing risk regression with bootstrap cross-validation.

RESULTS AND LIMITATIONS

Factors associated with BF after SRT include PSA DT <6 mo, initial postoperative PSA ≥0.2 ng/ml, higher pre-SRT PSA, lack of androgen deprivation therapy, a higher Gleason score (GS), negative margins, seminal vesicle invasion, lack of pelvic nodal radiation, radiation total dose <66 Gy, a longer RP to SRT interval, and older age (p < 0.05 for each). Factors associated with DM include PSA DT <6 mo, pre-SRT PSA, a higher GS, and negative margins. Factors associated with PCSM include PSA DT not calculable or <6 mo and a higher GS. Nomograms were generated to estimate the risks of BF (concordance index [CI] 0.74), DM (CI 0.77), and PCSM (CI 0.77). Limitations include retrospective nature, broad treatment eras, institutional variations, and multiple methods available for the estimation of PSA DT.

CONCLUSIONS

Postoperative PSA kinetics, particularly pre-SRT PSA and PSA DT, are strongly associated with adverse oncologic outcomes following SRT and should be considered in management decisions.

PATIENT SUMMARY

In this report of men with prostate cancer who developed a prostate-specific antigen (PSA) recurrence after prostatectomy, we found that PSA levels after surgery and how quickly a PSA level doubles significantly impact the chance of prostate cancer recurrence after salvage radiation therapy. Based on this information, we created a tool to calculate a man's chance of cancer recurrence after salvage radiation therapy, and these estimations can be used to discuss whether additional treatment with radiation should be considered.

Radiotherapy in nodal oligorecurrent prostate cancer

Objective

The current article encompasses a literature review and recommendations for radiotherapy in nodal oligorecurrent prostate cancer.

Materials and methods

A literature review focused on studies comparing metastasis-directed stereotactic ablative radiotherapy (SABR) vs. external elective nodal radiotherapy (ENRT) and studies analyzing recurrence patterns after local nodal treatment was performed. The DEGRO Prostate Cancer Expert Panel discussed the results and developed treatment recommendations.

Results

Metastasis-directed radiotherapy results in high local control (often > 90% within a follow-up of 1–2 years) and can be used to improve progression-free survival or defer androgen deprivation therapy (ADT) according to prospective randomized phase II data. Distant progression after involved-node SABR only occurs within a few months in the majority of patients. ENRT improves metastases-free survival rates with increased toxicity in comparison to SABR according to retrospective comparative studies. The majority of nodal recurrences after initial local treatment of pelvic nodal metastasis are detected within the true pelvis and common iliac vessels.

Conclusion

ENRT with or without a boost should be preferred to SABR in pelvic nodal recurrences. In oligometastatic prostate cancer with distant (extrapelvic) nodal recurrences, SABR alone can be performed in selected cases. Application of additional systemic treatments should be based on current guidelines, with ADT as first-line treatment for hormone-sensitive prostate cancer. Only in carefully selected patients can radiotherapy be initially used without additional ADT outside of the current standard recommendations. Results of (randomized) prospective studies are needed for definitive recommendations.

Prednisone reduction for metastatic castration-resistant prostate cancer with recurrent pulmonary tuberculosis: Case report

INTRODUCTION

Prednisone (10 mg/d) is often used in combination with docetaxel or abiraterone in the treatment of advanced prostate cancer. LATITUDE studies have confirmed that the combination of abiraterone and prednisone (5 mg/d) can be used for the treatment of newly diagnosed high-risk metastatic castration-sensitive prostate cancer, and have achieved satisfactory results. However, it has not been reported that abiraterone combined with prednisone (5 mg/d) in the treatment of metastatic castration-resistant prostate cancer (mCRPC).

PATIENT CONCERNS

Here, we present a case of high-risk advanced prostate cancer with old pulmonary tuberculosis (PTB). The patient developed a relapse of old tuberculosis in both lungs that were discovered following 14 months of continuous application of prednisone (10 mg/d).

DIAGNOSIS

The histopathological findings showed prostate adenocarcinoma carcinoma with a Gleason score of 10 (5+5). Further laboratory investigations were suggestive of positive mycobacterium tuberculosis complex DNA in pleural effusion and sputum.

INTERVENTIONS

The patient underwent endocrine therapy, chemotherapy of docetaxel plus prednisone, radiotherapy, and abiraterone combined with prednisone treatment, but he eventually developed into the mCRPC stage. Then, prednisone was reduced to 5 mg/d plus abiraterone, and combined with anti-tuberculosis treatment according to multi-disciplinary diagnosis and treatment.

OUTCOME

Two months later, pleural effusion and atelectasis were relieved, and PSA was remained stable at a low level. The patient achieved complete remission.

CONCLUSION

We cannot, with complete certainty, say that this patient, or any patient, developed old PTB recurrence due to the use of prednisone. Based on the current evidence, endocrine therapy is the foundation, radiotherapy can reduce the tumor load, and early application of abiraterone is beneficial to survival for the high-risk mCRPC. The long-term use of prednisone can be appropriately reduced in mCRPC with old PTB, and a satisfactory curative effect can be achieved. More prospective trials are warranted before a definite recommendation could be drawn.

Validation of a 22-Gene Genomic Classifier in Patients With Recurrent Prostate Cancer: An Ancillary Study of the NRG/RTOG 9601 Randomized Clinical Trial

Question

Can a genomic biomarker estimate the risk of prostate cancer clinical end points in men who received salvage radiation for rising prostate-specific antigen levels after surgery?

Findings

In this ancillary study of 352 men randomized to placebo or hormone therapy in the NRG/RTOG 9601 clinical trial of salvage radiation, the Decipher genomic classifier was independently associated with the risk of metastasis, prostate cancer–specific mortality, and overall survival.

Meaning

These findings suggest that the Decipher genomic classifier is a promising biomarker to risk stratify men to better enable hormone therapy treatment decisions for biochemical recurrence of their prostate cancer after surgery.

Importance

Decipher (Decipher Biosciences Inc) is a genomic classifier (GC) developed to estimate the risk of distant metastasis (DM) after radical prostatectomy (RP) in patients with prostate cancer.

Objective

To validate the GC in the context of a randomized phase 3 trial.

Design, Setting, and Participants

This ancillary study used RP specimens from the phase 3 placebo-controlled NRG/RTOG 9601 randomized clinical trial conducted from March 1998 to March 2003. The specimens were centrally reviewed, and RNA was extracted from the highest-grade tumor available in 2019 with a median follow-up of 13 years. Clinical-grade whole transcriptomes from samples passing quality control were assigned GC scores (scale, 0-1). A National Clinical Trials Network–approved prespecified statistical plan included the primary objective of validating the independent prognostic ability of GC for DM, with secondary end points of prostate cancer–specific mortality (PCSM) and overall survival (OS). Data were analyzed from September 2019 to December 2019.

Intervention

Salvage radiotherapy (sRT) with or without 2 years of bicalutamide.

Main Outcomes and Measures

The preplanned primary end point of this study was the independent association of the GC with the development of DM.

Results

In this ancillary study of specimens from a phase 3 randomized clinical trial, GC scores were generated from 486 of 760 randomized patients with a median follow-up of 13 years; samples from a total of 352 men (median [interquartile range] age, 64.5 (60-70) years; 314 White [89.2%] participants) passed microarray quality control and comprised the final cohort for analysis. On multivariable analysis, the GC (continuous variable, per 0.1 unit) was independently associated with DM (hazard ratio [HR], 1.17; 95% CI, 1.05-1.32; P = .006), PCSM (HR, 1.39; 95% CI, 1.20-1.63; P < .001), and OS (HR, 1.17; 95% CI, 1.06-1.29; P = .002) after adjusting for age, race/ethnicity, Gleason score, T stage, margin status, entry prostate-specific antigen, and treatment arm. Although the original planned analysis was not powered to detect a treatment effect interaction by GC score, the estimated absolute effect of bicalutamide on 12-year OS was less when comparing patients with lower vs higher GC scores (2.4% vs 8.9%), which was further demonstrated in men receiving early sRT at a prostate-specific antigen level lower than 0.7 ng/mL (−7.8% vs 4.6%).

Conclusions and Relevance

This ancillary validation study of the Decipher GC in a randomized trial cohort demonstrated association of the GC with DM, PCSM, and OS independent of standard clinicopathologic variables. These results suggest that not all men with biochemically recurrent prostate cancer after surgery benefit equally from the addition of hormone therapy to sRT.

Trial Registration

ClinicalTrials.gov identifier: NCT00002874

Intermediate clinical endpoints for surrogacy in localised prostate cancer: an aggregate meta-analysis

BACKGROUND

The international Intermediate Clinical Endpoints in Cancer of the Prostate working group has established metastasis-free survival as a surrogate for overall survival in localised prostate cancer based on the findings of 19 predominantly radiotherapy-based trials. We sought to comprehensively assess aggregate trial-level performance of commonly reported intermediate clinical endpoints across all randomised trials in localised prostate cancer.

METHODS

For this meta-analysis, we searched PubMed for all trials in localised or biochemically recurrent prostate cancer published between Jan 1, 1970, and Jan 15, 2020. Eligible trials had to be randomised, therapeutic, reporting overall survival and at least one intermediate clinical endpoint, and with a sample size of at least 70 participants. Trials of metastatic disease were excluded. Intermediate clinical endpoints included biochemical failure, local failure, distant metastases, biochemical failure-free survival, progression-free survival, and metastasis-free survival. Candidacy for surrogacy was assessed using the second condition of the meta-analytical approach (ie, correlation of the treatment effect of the intermediate clinical endpoint and overall survival), using R2 weighted by the inverse variance of the log intermediate clinical endpoint hazard ratio. The intermediate clinical endpoint was deemed to be a surrogate for overall survival if R2 was 0·7 or greater.

FINDINGS

75 trials (53 631 patients) were included in our analysis. Median follow-up was 9·1 years (IQR 5·7-10·6). Biochemical failure (R2 0·38 [95% CI 0·11-0·64]), biochemical failure-free survival (R2 0·12 [0·0030-0·33]), biochemical failure and clinical failure (R2 0·28 [0·0045-0·65]), and local failure (R2 0·085 [0·00-0·37]) correlated poorly with overall survival. Progression-free survival (R2 0·46 [95% CI 0·22-0·67]) showed moderate correlation with overall survival, and metastasis-free survival (R2 0·78 [0·59-0·89]) correlated strongly.

INTERPRETATION

Intermediate clinical endpoints based on biochemical and local failure did not meet the second condition of the meta-analytical approach and are not surrogate endpoints for overall survival in localised prostate cancer. Our findings validate metastasis-free survival as the only identified surrogate endpoint for overall survival to date.

FUNDING

Prostate Cancer Foundation and National Institutes of Health.

A Systematic Review and Meta-analysis of Local Salvage Therapies After Radiotherapy for Prostate Cancer (MASTER)

CONTEXT

Management of locally recurrent prostate cancer after definitive radiotherapy remains controversial due to the perceived high rates of severe genitourinary (GU) and gastrointestinal (GI) toxicity associated with any local salvage modality.

OBJECTIVE

To quantitatively compare the efficacy and toxicity of salvage radical prostatectomy (RP), high-intensity focused ultrasound (HIFU), cryotherapy, stereotactic body radiotherapy (SBRT), low-dose-rate (LDR) brachytherapy, and high-dose-rate (HDR) brachytherapy.

EVIDENCE ACQUISITION

We performed a systematic review of PubMed, EMBASE, and MEDLINE. Two- and 5-yr recurrence-free survival (RFS) rates and crude incidences of severe GU and GI toxicity were extracted as endpoints of interest. Random-effect meta-analyses were conducted to characterize summary effect sizes and quantify heterogeneity. Estimates for each modality were then compared with RP after adjusting for individual study-level covariates using mixed-effect regression models, while allowing for differences in between-study variance across treatment modalities.

EVIDENCE SYNTHESIS

A total of 150 studies were included for analysis. There was significant heterogeneity between studies within each modality, and covariates differed between modalities, necessitating adjustment. Adjusted 5-yr RFS ranged from 50% after cryotherapy to 60% after HDR brachytherapy and SBRT, with no significant differences between any modality and RP. Severe GU toxicity was significantly lower with all three forms of radiotherapeutic salvage than with RP (adjusted rates of 20% after RP vs 5.6%, 9.6%, and 9.1% after SBRT, HDR brachytherapy, and LDR brachytherapy, respectively; p ≤ 0.001 for all). Severe GI toxicity was significantly lower with HDR salvage than with RP (adjusted rates 1.8% vs 0.0%, p < 0.01), with no other differences identified.

CONCLUSIONS

Large differences in 5-yr outcomes were not uncovered when comparing all salvage treatment modalities against RP. Reirradiation with SBRT, HDR brachytherapy, or LDR brachytherapy appears to result in less severe GU toxicity than RP, and reirradiation with HDR brachytherapy yields less severe GI toxicity than RP. Prospective studies of local salvage for radiorecurrent disease are warranted.

PATIENT SUMMARY

In a large study-level meta-analysis, we looked at treatment outcomes and toxicity for men treated with a number of salvage treatments for radiorecurrent prostate cancer. We conclude that relapse-free survival at 5 years is equivalent among salvage modalities, but reirradiation may lead to lower toxicity.

Outcome After 68Ga-PSMA-11 versus Choline PET-Based Salvage Radiotherapy in Patients with Biochemical Recurrence of Prostate Cancer: A Matched-Pair Analysis

The purpose of this analysis was primarily to analyze biochemical-recurrence free survival (BRFS) after positron emission tomography (PET)-guided salvage radiotherapy (sRT) in a large cohort, and to further compare BRFS after PSMA vs. choline PET/ computer tomography (CT)-based sRT. This retrospective analysis is based on 421 patients referred for PSMA or choline PET/CT after radical prostatectomy due to biochemically recurrent or persistent disease. BRFS (PSA: 0.2 ng/mL) was defined as the study endpoint. Cox regression analyses were performed to assess the impact of different clinical parameters on BRFS. Additionally, propensity score matching was performed to adjust patient cohorts (PSMA vs. choline PET/CT-based sRT). The median follow-up time was 30 months. BRFS at three years after sRT was 58%. In the multivariate analysis, only PSA before PET imaging and PSA before sRT were significantly associated with BRFS (p < 0.05). After propensity score matching, 272 patients were further analyzed; there was no significant difference in three-year BRFS between patients with PSMA PET-based vs. choline PET-based sRT (55% vs. 63%, p = 0.197). The present analysis confirmed the overall high BRFS rates after PET-based sRT and the strong prognostic effect of PSA level prior to sRT. PSMA PET-based sRT did not have superior BRFS rates when compared with choline PET-based sRT.