Metastasis-directed therapy in oligometastatic prostate cancer

PURPOSE OF REVIEW

To summarize the recent findings on the subject of metastasis-directed therapy (MDT) in the treatment of oligometastatic prostate cancer (omPCa).

RECENT FINDINGS

Evidence from two randomized clinical trials (RCTs) and a meta-analysis show favorable toxicity profiles, and the potential to delay androgen-deprivation therapy (ADT) for up to two years in nearly half of patients with metachronous hormone-sensitive omPCa. Another RCT showed promising results of MDT as treatment-escalation method combined with androgen receptor signaling inhibitors (ARSI) in first-line treatment for castration-resistant omPCa.Surveys by radiation oncologists and consensus guidelines advocate for MDT across various omPCa scenarios. Multiple single-arm trials present encouraging results; however, the evidence for the benefit of MDT is still weak requiring further investigation to assess its impact on pivotal endpoints, such as survival and quality of life.

SUMMARY

MDT is a promising approach in omPCa, and can be used to defer ADT in newly diagnosed metachronous omPCa patients, or to add to ARSI treatment at first diagnosis of castration-resistance. Ongoing prospective trials are needed to guide its optimal utilization in other settings, and patients should be informed about the evolving landscape of systemic therapies with proven survival benefits alongside MDT options.

Stereotactic ablative radiation therapy in metastatic prostate cancer

PURPOSE OF REVIEW

The evolving role of stereotactic ablative radiation therapy (SABR) as metastasis-directed therapy (MDT) for oligometastatic prostate cancer (omPCa) will be discussed.

RECENT FINDINGS

Oligometastatic disease (OMD) is an intermediate state between localized and wide-spread malignant disease. OMD has recently been spotlighted given the increasing demonstration of clinical benefit from local therapies despite presence of metastatic disease and allure of the curative potential of MDT in select cases. Among the different forms of MDT, SABR has rapidly become a widely adopted treatment modality. Significant efforts in this space have focused on omPCa, owing to its relatively indolent biology, presence of a sensitive and specific serum biomarker and recent advances in molecular imaging. While most studies have evaluated the role of SABR MDT in hormone sensitive omPCa, new emerging clinical data also suggests benefits of SABR MDT for even castration-resistant disease.

SUMMARY

Treating omPCa with SABR MDT appears to generate an efficacy signal with minimal morbidity across both hormone-sensitive and castration-resistant disease. However, additional definitive omPCa trial data are needed. Future research efforts should investigate biomarkers for this heterogeneous disease space and the role of SABR MDT in combination with systemic agents to improve upon standard of care treatments.

Treatment modalities and survival outcomes in prostate cancer parenchymal brain metastasis

BACKGROUND

Prostate cancer (PCa) parenchymal brain metastases are uncommon and troubling observations in the course of the disease. Our study aims to evaluate the prevalence of brain metastases among PCa patients while reporting various therapeutic modalities, clinical features, and oncological outcomes.

METHODS

We retrospectively identified 34 patients with parenchymal brain metastasis out of 4575 patients using a prospectively maintained database that contains clinicopathologic characteristics of PCa patients between January 2012 and December 2021. Based on the three treatment modalities used, the patients were divided into three groups: stereotactic radiosurgery (SRS), whole brain radiotherapy (WBRT), and systemic therapy alone. The Kaplan-Meier curve was used to calculate overall survival [OS] probability and the Cox proportional hazards regression model was used to compare between groups.

RESULTS

At the time of brain metastasis diagnosis, the median age was 66 years, the median (interquartile range [IQR]) prostate-specific antigen (PSA) was 2.2 (0.1-26.6) ng/ml and the median (IQR) months from initial PCa diagnosis to brain metastasis development was 70.8 (27.6-100.9). The median (IQR) primary Gleason score was 8 (7-9) and over a median (IQR) follow-up time of 2.2 (1.2-16.5) months, 76.5% (n = 26) of the patients died. Thirteen (38.2%) patients had solitary lesion, whereas 21 (61.8%) had ≥2 lesions. The lesions were supratentorial in 19 (55.9%) patients, infratentorial in six (17.6%), and both sides in nine (26.5%). Among all 34 patients, 10 (29.4%) were treated with SRS, seven (20.6%) with WBRT, and 17 (50%) with systemic therapy alone. OS varied greatly between the three treatment modalities (log-rank test, p = 0.049). Those who were treated with SRS and WBRT had better OS compared with patients who were treated with systemic therapy alone (hazard ratio: 0.37, 95% confidence interval: 0.16-0.86, p = 0.022).

CONCLUSIONS

In our single-institutional study, we confirmed that PCa brain metastasis is associated with poor survival outcomes and more advanced metastatic disease. Furthermore, we found that SRS and WBRT for brain metastasis in patients with recurrent PCa appear to be associated with improved OS as compared with systemic therapy alone and are likely secondary to selection bias.

Progress in Oligometastatic Prostate Cancer: Emerging Imaging Innovations and Therapeutic Approaches

Prostate cancer (PCa) exhibits a spectrum of heterogeneity, from indolent to highly aggressive forms, with approximately 10-20% of patients experiencing metastatic PCa. Oligometastatic PCa, characterized by a limited number of metastatic lesions in specific anatomical locations, has gained attention due to advanced imaging modalities. Although patients with metastatic PCa typically receive systemic therapy, personalized treatment approaches for oligometastatic PCa are emerging, including surgical and radiotherapeutic interventions. This comprehensive review explores the latest developments in the field of oligometastatic PCa, including its biological mechanisms, advanced imaging techniques, and relevant clinical studies. Oligometastatic PCa is distinct from widespread metastases and presents challenges in patient classification. Imaging plays a crucial role in identifying and characterizing oligometastatic lesions, with new techniques such as prostate-specific membrane antigen positron emission tomography demonstrating a remarkable efficacy. The management strategies encompass cytoreductive surgery, radiotherapy targeting the primary tumor, and metastasis-directed therapy for recurrent lesions. Ongoing clinical trials are evaluating the effectiveness of these approaches. Oligometastatic PCa occupies a unique position between locally advanced and high-volume metastatic diseases. While a universally accepted definition and standardized diagnostic criteria are still evolving, emerging imaging technologies and therapeutic strategies hold promise for improving the patient outcomes in this intermediate stage of PCa.

EAU Biochemical Recurrence Risk Classification and PSA Kinetics Have No Value for Patient Selection in PSMA-Radioguided Surgery (PSMA-RGS) for Oligorecurrent Prostate Cancer

OBJECTIVE

To assess the influence of biochemical recurrence (BCR) risk groups and PSA kinetics on the outcomes of radioguided surgery against prostate-specific membrane antigen (PSMA-RGS). Currently, neither BCR risk group nor PSA doubling time (PSA-DT), or PSA velocity (PSA-V) are actively assigned or relevant for counseling prior to PSMA-RGS.

METHODS

We retrospectively analyzed PSMA-RGS cases for oligorecurrent prostate cancer between 2014 and 2023. BCR risk groups, PSA-DT, and PSA-V were analyzed as predictors for complete biochemical response (cBR, PSA < 0.2 ng/mL), BCR-free, and therapy-free survival (BCRFS, TFS).

RESULTS

Of 374 included patients, only 21/374 (6%) and 201/374 (54%) were classified as low- and high-risk BCR (no group assignment possible in 152/374, 41%). A total of 13/21 (62%) patients with low- and 120/201 (60%) with high-risk BCR achieved cBR (p = 1.0). BCR classification was no predictor for BCRFS (HR:1.61, CI: 0.70-3.71, p = 0.3) or subsequent TFS (HR:1.07, CI: 0.46-2.47, p = 0.9). A total of 47/76 (62%) patients with PSA-DT ≤ 6 mo and 50/84 (60%) with PSA-DT > 6 mo achieved cBR (p = 0.4). PSA-DT was not associated with cBR (OR: 0.99, CI: 0.95-1.03, p = 0.5), BCRFS (HR: 1.00, CI: 0.97-1.03, p = 0.9), or TFS (HR: 1.02, CI: 0.99-1.04, p = 0.2). Consistent negative findings were recorded for PSA-V.

CONCLUSIONS

The BCR risk groups and PSA kinetics do not predict the oncological success of PSMA-RGS performed at low absolute PSA values. Indolent low-risk BCR is rarely treated by PSMA-RGS.

American Radium Society Appropriate Use Criteria for the use of liver-directed therapies for nonsurgical management of liver metastases: Systematic review and guidelines

The liver is a common site of cancer metastases. Systemic therapy is widely accepted as the standard treatment for liver metastases (LM), although select patients with liver oligometastases may be candidates for potentially curative liver resection. Recent data support the role of nonsurgical local therapies such as ablation, external beam radiotherapy, embolization, and hepatic artery infusion therapy for management of LM. Additionally, for patients with advanced, symptomatic LM, local therapies may provide palliative benefit. The American Radium Society gastrointestinal expert panel, including members representing radiation oncology, interventional radiology, surgical oncology, and medical oncology, performed a systemic review and developed Appropriate Use Criteria for the use of nonsurgical local therapies for LM. Preferred Reporting Items for Systematic reviews and Meta-Analyses methodology was used. These studies were used to inform the expert panel, which then rated the appropriateness of various treatments in seven representative clinical scenarios through a well-established consensus methodology (modified Delphi). A summary of recommendations is outlined to guide practitioners on the use of nonsurgical local therapies for patients with LM.

Node Oligorecurrence in Prostate Cancer: A Challenge

Within the oligometastatic state, oligorecurrent lymph node disease in prostate cancer represents an interesting clinical entity characterized by a relatively indolent biology that makes it unique: it can be treated radically, and its treatment is usually associated with a long period of control and excellent survival. Additionally, it is an emergent situation that we are facing more frequently mainly due to (a) the incorporation into clinical practice of the PSMA-PET that provides strikingly increased superior images in comparison to conventional imaging, with higher sensitivity and specificity; (b) the higher detection rates of bone and node disease with extremely low levels of PSA; and (c) the availability of high-precision technology in radiotherapy treatments with the incorporation of stereotaxic body radiotherapy (SBRT) or stereotaxic ablative radiotherapy (SABR) technology that allows the safe administration of high doses of radiation in a very limited number of fractions with low toxicity and excellent tolerance. This approach of new image-guided patient management is compelling for doctors and patients since it can potentially contribute to improving the clinical outcome. In this work, we discuss the available evidence, areas of debate, and potential future directions concerning the utilization of new imaging-guided SBRT for the treatment of nodal recurrence in prostate cancer.

Role of radiation in oligometastases and oligoprogression in metastatic non-small cell lung cancer: consensus and controversy

INTRODUCTION

The oligometastatic state in non-small cell lung cancer (NSCLC) has recently become well-established. However, the specific definition of oligometastases remains unclear. Several smaller randomized studies have investigated the safety and efficacy of radiation as metastasis-directed therapy (MDT) in oligometastatic NSCLC, which have led the way to larger studies currently accruing patients globally.

AREAS COVERED

This review covers the definitions of 'oligometastases' and explains why the oligometastatic state is becoming increasingly relevant in metastatic NSCLC. This includes the rationale for MDT in oligometastatic NSCLC, specifically reviewing stereotactic body radiation therapy (SBRT) as a treatment strategy. This review details many randomized trials that support radiation as MDT and introduces trials that are currently accruing patients. Finally, it explores some of the controversies that warrant further investigation.

EXPERT OPINION

Radiation treatment, specifically SBRT, has been shown to be safe, convenient, and cost-effective as MDT. As systemic therapy, including targeted agents and immunotherapy, continues to improve, the precise role(s) and timing of radiation therapy may evolve. However, radiation therapy as MDT will continue to be an integral part of treatment in patients with oligometastatic NSCLC.

Comprehensive analysis of Japanese nationwide cohort data of particle beam therapy for pulmonary, liver and lymph node oligometastases: particle beam therapy versus high-precision X-ray radiotherapy

Japanese national oncological experts convened to evaluate the efficacy and safety of particle beam therapy (PT) for pulmonary, liver and lymph node oligometastases (P-OM, L-OM and LN-OM, respectively) and to conduct a statistically comparative analysis of the local control (LC) rate and overall survival (OS) rate of PT versus those of X-ray stereotactic body radiotherapy (X-SBRT) and X-ray intensity-modulated radiotherapy (X-IMRT). They conducted [1] an analysis of the efficacy and safety of metastasis-directed therapy with PT for P-OM, L-OM and LN-OM using a Japanese nationwide multi-institutional cohort study data set; [2] a systematic review of X-ray high-precision radiotherapy (i.e. X-SBRT/X-IMRT) and PT for P-OM, L-OM and LN-OM; and [3] a statistical comparison between LC and OS of the cohort data set in PT and that of the extracted historical data set in X-SBRT/X-IMRT from the preceding systematic review. Safety was evaluated as the incidence of grade ≥ 3 adverse events, while statistical comparisons of LC and OS were conducted by estimating the incidence rate ratios (IRR) for local progression and mortality, respectively. This study demonstrated that PT provided durable LC (3-year LC rate: 72.8-83.2%) with acceptable OS (3-year OS rate: 38.5-68.1%) and risk of severe toxicity incidence of 0.8-3.5% in radical metastasis-directed therapy for P-OM, L-OM and LN-OM. Compared to LC with X-SBRT or X-IMRT, LC with PT was potentially superior for P-OM; superior for L-OM; and equivalent for LN-OM. In particular, this study demonstrated that PT may be a new treatment option for L-OM tumors measuring > 5 cm.

Is The Patient Actually Failing On Enzalutamide? A Case Report And Issues To Consider In Enzalutamide-Resistant Oligo Progressive Metastatic Castrate-Resistant Prostate Cancer

BACKGROUND

Metastatic castrate-resistant prostate cancer (mCRPC) is a challenging disease, especially in heavily pretreated patients. Androgen pathway inhibitors have contributed to a notable improvement in the overall survival and quality of life in patients with mCRPC during the last decade. Still, a considerable percentage of patients are unable to draw benefits from this drug category and are deprived of a treatment that offers limited toxicity and preserves a good quality of life. The mechanisms leading to this pre-existing or acquired resistance, as well as the possible strategies to overcome this resistance have been put at the center of scientists' attention.

CASE PRESENTATION

With the present report we present the case of a 70-year-old patient with mCRPC, who was apparently an enzalutamide non-responder, but a multimodal approach with enzalutamide continuation and irradiation to his symptomatic oligoprogressive disease converted him to a responder with clinical, biochemical and imaging response; furthermore, we discuss the existing data providing evidence for the use of metastasis-directed therapy in combination with androgen pathway inhibitors in order to overcome drug resistance in patients with oligoprogressive disease.

CONCLUSION

A considerable proportion of patients with oligometastatic or oligoprogressive prostate cancer who seem not to respond to androgen pathway inhibitors, such as enzalutamide, due to preexisting or acquired resistance, could benefit from MDT with a multimodal treatment approach. This strategy allows androgen pathway inhibitor continuation beyond biochemical progression and delays the switch to next-line systemic treatment.

A Retrospective Multicenter Analysis of the Incidence of Bone-Only Disease at PSMA PET/CT in Castration Resistant Prostate Cancer Patients

PSMA PET/CT has unprecedented accuracy for localization of initial or recurrent prostate cancer (PC), which can be applied in a metastasis-directed therapy approach. PSMA PET/CT (PET) also has a role in the selection of patients for metastasis-directed therapy or radioligand therapy and therapy assessment in CRPC patients. The purpose of this multicenter retrospective study was to determine the incidence of bone-only metastasis in CRPC patients who underwent PSMA PET/CT for restaging, as well as identifying potential predictors of bone-only PET positivity. The study analyzed data from 179 patients from two centers in Essen and Bologna. Results showed that 20.1% of the patients had PSMA uptake only in the bone, with the most frequent lesions located in the vertebrae, ribs, and hip bone. Half half of the patients showed oligo disease in bone and may benefit from a bone-metastasis-directed therapy. Initial positive nodal status and solitary ADT were shown to be negative predictors of osseous metastasis. The role of PSMA PET/TC in this patient population needs to be further explored in terms of its role in the evaluation and adoption of bone-specific therapies.

Difficulties in Defining Oligometastatic Prostate Cancer: Implications for Clinical Trial Accrual and Community Practice Adoption of Metastasis-Directed Therapy Approaches

BACKGROUND

Metastasis-directed therapy is widely utilized for oligometastatic prostate cancer patients, but standard imaging does not always identify metastases definitively and, even with PSMA PET, there may be equivocal findings. Not all clinicians have access to detailed imaging review, particularly outside of academic cancer centers, and PET scan access is also limited. We sought to understand how imaging interpretation impacted recruitment to a clinical trial for oligometastatic prostate cancer.

METHODS

IRB approval was obtained to review medical records from all patients screened for the institutional IRB-approved clinical trial for men with oligometastatic prostate cancer involving androgen deprivation plus stereotactic radiation to all metastatic sites, as well as radium223 (NCT03361735). Clinical trial inclusion required at least one bone metastatic lesion and no more than five total sites of metastasis, including soft tissue sites. Tumor board discussion records were reviewed, along with results from additional radiology studies ordered or confirmatory biopsies performed. Clinical characteristics such as PSA level and Gleason score were studied for association with likelihood of oligometastatic disease confirmation.

RESULTS

At the time of data analysis, 18 subjects were deemed eligible and 20 were not eligible. The most common reasons for ineligibility were no confirmed bone metastasis in 16 patients (59%) and too many metastatic sites in 3 (11%). The median PSA of eligible subjects was 3.28 (range 0.4-45.5), whereas the median PSA of those found to be ineligible was 10.45 (range 3.7-26.3) when there were too many metastases identified, and 2.7 (range 0.2-34.5) when metastases were unconfirmed. PET imaging (PSMA or fluciclovine PET) increased the number of metastases, while MRI resulted in downstaging to non-metastatic disease.

CONCLUSIONS

This research suggests that additional imaging (i.e., at least two independent imaging modalities of a possible metastatic lesion) or tumor board adjudication of imaging findings may be critical to correctly identify patients appropriate for enrollment in oligometastatic protocols. This should be considered as trials of metastasis-directed therapy for oligometastatic prostate cancer accrue and results are translated to broader oncology practice.

Prostate and metastasis-directed focal therapy in prostate cancer: hype or hope?

INTRODUCTION

The paradigm of focal therapy's role in metastatic patients is being challenged by evolving attitudes and emerging data. At the current time, specifically regarding prostate cancer, does the evidence indicate this is more hype or hope?

AREAS COVERED

We searched the literature via PubMed, MEDLINE, and Embase for studies from 2014 to the present addressing focal therapy with non-palliative intent in metastatic prostate cancer patients, emphasizing prospective trials when available. We sought to address all common clinical scenarios: de novo synchronous diagnosis, oligorecurrence, oligoprogression, and mCRPC disease.

EXPERT OPINION

Current evidence is strongest, and in our opinion practice-changing, for prostate-directed RT in de novo metastatic patients with low metastatic burden. Metastasis-directed therapy with SBRT is consistently shown to have low rates of toxicity, and promising rates of ADT-free survival and progression-free survival. These can be utilized on a patient-by-patient basis with these endpoints in mind, but do not yet show sufficient benefit to be standard of care. This is a rich area of ongoing research, and many trials should publish in the coming years to shed light on many unanswered questions, including the role of cytoreductive prostatectomy, systemic therapy combined with MDT, and the integration of modern PET imaging.

Oligometastatic Prostate Cancer Treated with Metastasis-Directed Therapy Guided by Positron Emission Tomography: Does the Tracer Matter?

The superior diagnostic accuracy of [68Ga]Ga-prostate-specific membrane antigen-11 (PSMA) ([68Ga]Ga-PSMA-11) compared to [18F]F-Fluorocholine Positron Emission Tomography/Computed Tomography (PET/CT) in Prostate Cancer (PCa) is established. However, it is currently unclear if the added diagnostic accuracy actually translates into improved clinical outcomes in oligometastatic PCa patients treated with [68Ga]Ga-PSMA-11 PET-guided metastasis-directed therapy (MDT). The present study aimed to assess the impact of these two imaging techniques on Progression-Free Survival (PFS) in a real-world sample of oligometastatic PCa patients submitted to PET-guided MDT. Thirty-seven oligometastatic PCa patients treated with PET-guided MDT were retrospectively enrolled. MDT was guided by [18F]F-Fluorocholine PET/CT in eleven patients and by [68Ga]Ga-PSMA-11 PET/CT in twenty-six. Progression was defined as biochemical recurrence (BR), radiological progression at subsequent PET/CT imaging, clinical progression, androgen deprivation therapy initiation, or death. Clinical and imaging parameters were assessed as predictors of PFS. [18F]F-Fluorocholine PET-guided MDT was associated with significantly lower PFS compared to the [68Ga]Ga-PSMA-11 group (median PFS, mPFS 15.47 months, 95% CI: 4.13−38.00 vs. 40.93 months, 95% CI: 40.93−40.93, respectively; p < 0.05). Coherently, the radiotracer used for PET-guided MDT resulted in predictive PFS at the univariate analysis, as well as the castration-resistant status at the time of MDT and the PSA nadir after MDT. However, in the multivariate analysis, castration resistance and PSA nadir after MDT remained the sole independent predictors of PFS. In conclusion, in the present proof-of-concept study, [68Ga]Ga-PSMA-11 provided higher PFS rates than [18F]F-Fluorocholine imaging in oligometastatic PCa patients receiving PET-guided MDT. Although preliminary, this finding suggests that enlarging the “tip of the iceberg”, by detecting a major proportion of the submerged disease thanks to next-generation imaging may favourably impact the oncological outcome of oligometastatic PCa treated with MDT.

Defining the optimal template of salvage lymph node dissection for unilateral pelvic nodal recurrence of prostate cancer following radical prostatectomy

OBJECTIVES

Several retrospective studies have shown that salvage bilateral pelvic lymph node dissection (sLND) is a valid treatment option in the setting of oligorecurrent nodal prostate cancer following radical prostatectomy. Little is known about the optimal template of such sLND in patients with strictly unilateral pelvic recurrence on PET-CT imaging. In this study, we investigated whether a unilateral pelvic sLND could be sufficient in such a setting.

METHODS

We retrospectively collected data of patients treated with sLND between 2010 and 2019 at the University Hospitals, Leuven. Patients were included if they developed recurrence following radical prostatectomy, characterized by ≤3 unilateral pelvic lymph node metastases on Choline or PSMA PET-CT and received a super-extended bilateral pelvic sLND as first metastasis-directed therapy. As a primary endpoint, we investigated in how many cases a unilateral sLND would have been sufficient.

RESULTS

In total, 44 patients with strictly unilateral pelvic recurrence were treated with super-extended bilateral pelvic sLND. In 5 out of 44 (11%) patients, histological examination showed presence of prostate cancer in the contralateral hemi-pelvis. In the group with a single positive node on imaging prior to sLND, only 1 out of 27 (3%) patients had contralateral disease at final pathology. No one (0%) in this group subsequently developed recurrence in the contralateral hemi-pelvis following sLND.

CONCLUSIONS

In conclusion, this study suggests that unilateral pelvic sLND could be sufficient in patients with a single unilateral pelvic lymph node recurrence on PET/CT imaging.

Choline PET/CT in recurrent prostate cancer

Purpose

Biochemical recurrence (BR) occurs in up to 40% of patients with prostate cancer (PCa) treated with primary radical prostatectomy (RP). Choline PET/CT may show, in a single-step examination, the site of tumor recurrence earlier than traditional imaging methods, particularly at low prostate-specific antigen (PSA) levels, thus influencing subsequent treatment.

Methods/patients

Patients with recurrent and non-metastatic prostate cancer (nmPCa), who were assessed with choline PET/CT, were included in the analysis. Based on imaging results, the following therapeutic strategies were chosen: radiotherapy to the prostatic bed, androgen deprivation therapy (ADT), and chemotherapy or stereotactic body radiotherapy (SBRT) to either the pelvic lymph nodes or distant metastases. We assessed the impact of age, PSA levels, Gleason score (GS), and adjuvant therapy on oncological outcomes.

Results

Data from 410 consecutive nmPCa patients with BR who underwent RP as primary treatment were analyzed. One hundred seventy-six (42.9%) patients had a negative choline PET/CT, and 234 (57.1%) patients resulted positive. In the multivariate analysis, only chemotherapy and PSA at recurrence were significant independent prognostic factors on overall survival (OS). In the PET-positive subgroup, the number of relapses, PSA post-prostatectomy, and chemotherapy impacted on OS. PSA (post-surgery and at recurrence) affected progression-free survival (PFS) in the univariate analysis. In the multivariate analysis, GS, the number of relapse sites, and PSA (post-surgery and at recurrence) were significant prognostic factors for disease-free survival (DFS).

Conclusion

Choline PET/CT provides better accuracy than conventional imaging for the assessment of nmPCa with BR after prostatectomy, thereby enabling salvage strategies and improving quality of life.

The current role of precision surgery in oligometastatic prostate cancer

Oligometastatic prostate cancer (omPCa) is a novel intermediate disease state characterized by a limited volume of metastatic cells and specific locations. Accurate staging is paramount to unmask oligometastatic disease, as provided by prostate-specific membrane antigen-positron emission tomography. Driven by the results of prospective trials employing conventional and/or modern staging modalities, the treatment landscape of omPCa has rapidly evolved over the last years. Several treatment-related questions comprising the concept of precision strikes are under development. For example, beyond systemic therapy, cohort studies have found that cytoreductive radical prostatectomy (CRP) can confer a survival benefit in select patients with omPCa. More importantly, CRP has been consistently shown to improve long-term local symptoms when the tumor progresses across disease states due to resistance to systemic therapies. Metastasis-directed treatments have also emerged as a promising treatment option due to the visibility of oligometastatic disease and new technologies as well as treatment strategies to target the novel PCa colonies. Whether metastases are present at primary cancer diagnosis or detected upon biochemical recurrence after treatment with curative intent, targeted yet decisive elimination of disseminated tumor cell hotspots is thought to improve survival outcomes. One such strategy is salvage lymph node dissection in oligorecurrent PCa which can alter the natural history of progressive PCa. In this review, we will highlight how refinements in modern staging modalities change the classification and treatment of (oligo-)metastatic PCa. Further, we will also discuss the current role and future directions of precision surgery in omPCa.

Highlighting the Place of Metastasis-Directed Therapy in Isolated Liver Metastases in Prostate Cancer: A Case Report

Metastatic prostate cancer remains a challenge for clinicians. Metastases involve mainly the bone compartment and can manifest as oligometastatic disease. In this setting, the role of metastasis-directed therapies (MDT) including surgery and/or stereotactic body radiotherapy is currently evaluated. Visceral metastases are less common and have very poor prognosis in mPC. Whether treating isolated visceral metastases such as liver metastases with MDT could increase the prognosis remains unknown. We report the management of a prostate cancer patient who progressed on androgen deprivation therapy with apparition of two liver metastases. We describe the feasibility of combining MDT with abiraterone acetate and prednisone in a patient with metastatic castration-resistant prostate cancer. MDT allowed the interruption of abiraterone acetate, preventing cumulative toxicity of this agent.

Volumetric burden of metastatic lesions drives outcomes in patients with extracranial oligometastatic disease

Background

We hypothesized that the total volume of metastases at initial oligometastatic (OM) presentation to stereotactic body radiation therapy (SBRT) is an important prognostic factor that can refine the definition of OM disease.

Methods

Patients with extracranial oligometastatic cancer (≤5 lesions) treated with SBRT were included in an international multi‐institutional database. Multivariable Cox and competing risks regression models were used to determine the relationship between distant progression‐free survival (DPFS), widespread progression (WSP), and overall survival (OS) with the total planning target volume (PTV) at initial OM presentation to SBRT. All models were adjusted for histology, pre‐SBRT systemic therapy, osseous‐only lesions, and number of metastases.

Results

In total, 961 patients were included. The median follow‐up was 24.4 months (IQR: 13.8–37.5). Total PTV had a significant effect on DPFS in the first 18 months after SBRT and was most profound in the first 6 months, when each twofold increase in total PTV conferred a 40.6% increased risk of distant progression (p < 0.001). Each twofold increase in total PTV increased the risk of WSP by 45.4% in the first 6 months (p < 0.001). Total PTV had a significant effect on OS in the first 2 years after SBRT, with each twofold PTV change increasing the risk of death by 60.7% during the first 6 months (p < 0.001) and by 34% thereafter (p < 0.001). Exploratory gross tumor volume (GTV) analysis confirmed the PTV‐based observations.

Conclusion

The total volumetric burden of metastases at initial OM presentation to SBRT is strongly and independently prognostic for the risk of distant and widespread progression and survival. We propose that this metric should drive the definition of OM disease and guide treatment decision‐making.

Oligometastatic Disease Detection with 68Ga-PSMA-11 PET/CT in Hormone-Sensitive Prostate Cancer Patients (HSPC) with Biochemical Recurrence after Radical Prostatectomy: Predictive Factors and Clinical Impact

Metastasis-directed therapy (MDT) in oligometastatic prostate cancer has the potential of delaying the start of androgen deprivation therapy (ADT) and disease progression. We aimed to analyze the efficacy of PSMA-PET/CT in detecting oligometastatic disease (OMD), to look for predictive factors of OMD, and to evaluate the impact of PSMA-PET/CT findings on clinical management. We retrospectively analyzed a homogeneous population of 196 hormone-sensitive prostate cancer patients (HSPC), considered potential candidates for MDT, with a PSMA-PET/CT performed at biochemical recurrence (BCR) after radical prostatectomy (RP). Multivariable logistic regression analysis was performed based on several clinico-pathological factors. Changes in clinical management before and after PSMA-PET/CT were analyzed. The OMD detection rate was 44% for a total positivity rate of 60%. PSMA-PET/CT positivity was independently related to PSA (OR (95% CI), p) (1.7 (1.3-2.3), p < 0.0001) and PSAdt (0.4 (0.2-0.8), p = 0.013), and OMD detection was independently related to PSA (1.6 (1.2-2.2), p = 0.001) and no previous salvage therapy (0.3 (0.1-0.9), p = 0.038). A treatment change was observed in 58% of patients, mostly to perform MDT after OMD detection (60% of changes). This study showed that PSMA-PET/CT is an excellent imaging technique to detect OMD early in HSPC patients with BCR after RP, changing therapeutic management mostly into MDT.

Progression-free survival in patients with 68Ga-PSMA-PET-directed SBRT for lymph node oligometastases

BACKGROUND

Prostate cancer oligometastatic disease can be treated using stereotactic body radiotherapy (SBRT) in order to postpone start of systemic treatments such as androgen deprivation therapy (ADT). 68Ga-PSMA-PET/CT imaging allows for diagnosis of oligometastases at lower PSA values. We analysed a cohort of patients with prostate cancer lymph node oligometastases detected on PSMA-PET/CT.

MATERIALS AND METHODS

Ninety patients with metachronous oligometastatic prostate cancer received SBRT for 1-3 lymph node metastases diagnosed on 68Ga-PSMA-PET/CT. The primary end point was progression free survival (PFS), with disease progression defined as occurrence of either target lesion progression, new metastatic lesion or biochemical progression. Secondary outcomes were biochemical PFS (BPFS), ADT-free survival (ADT-FS), toxicity and quality of life (QoL). Baseline patient characteristics were tested for association with PFS and a preliminary risk score was created.

RESULTS

Median follow-up was 21 months (interquartile range 10-31 months). Median PFS and BPFS were 16 and 21 months, respectively. Median ADT-FS was not reached (73% (95%-CI 62-86%) at 24 months). In multivariable analysis, younger age, higher PSA prior to SBRT and extrapelvic location were associated with shorter PFS. Grade 1 fatigue was the most predominant acute toxicity (34%). Highest grade toxicity was grade 2 for acute and late events. QoL analysis showed mild, transient increase in fatigue at 1-4 weeks after SBRT.

CONCLUSION

A median PFS of 16 months was attained after SBRT for patients with PSMA-PET positive oligometastatic lymph nodes from prostate cancer. Higher pre-SBRT PSA, younger age and extrapelvic location were found to be predictors of shorter PFS.

Efficacy of PSMA PET-Guided Radiotherapy for Oligometastatic Castrate-Resistant Prostate Cancer

Purpose

To assess the outcome of radiotherapy (RT) to all PSMA ligand positive metastases for patients with castrate-resistant prostate cancer (mCRPC).

Patients and methods

A total of 42 patients developed oligometastatic mCRPC and received PSMA PET-guided RT of all metastases. The main outcome parameters were biochemical progression-free survival (bPFS), and second-line systemic treatment free survival (SST-FS).

Results

A total of 141 PSMA ligand-positive metastases were irradiated. The median follow-up time was 39.0 months (12-58 months). During the follow-up five out of 42 (11.9%) patients died of progressive mPCa. Five out of 42 (11.9%) patients showed no biochemical responses and presented with a PSA level ≥10% of the baseline PSA at first PSA level measurement after RT and were classified as non-responders. The median PSA level before RT was 4.79 ng/mL (range, 0.4-46.1), which decreased significantly to a median PSA nadir level of 0.39 ng/mL (range, <0.07-32.8; p=0.002). The median PSA level at biochemical progression after PSMA ligand-based RT was 2.75 ng/mL (range, 0.27-53.0; p=0.24) and was not significantly different (p=0.29) from the median PSA level (4.79 ng/mL, range, 0.4-46.1) before the PSMA ligand-based RT. The median bPFS was 12.0 months after PSMA ligand PET-based RT (95% CI, 11.2-15.8) and the median SST-FS was 15.0 months (95% CI, 14.0-21.5).

Conclusion

In well-informed and closely followed-up patients, PSMA PET-guided RT represents a viable treatment option for patients with oligometastatic mCRPC to delay further systemic therapies.

Long-term clinical outcomes of external beam radiation therapy for oligometastatic prostate cancer: A combination of prostate-targeted treatment and metastasis-directed therapy

OBJECTIVE

To assess the efficacy of combination of prostate-targeted treatment and metastasis-directed therapy for oligometastatic prostate cancer.

METHODS

We retrospectively evaluated the clinical outcomes of synchronously diagnosed oligometastatic prostate cancer patients treated with external beam radiation therapy for the prostate and all metastatic lesions (≤3 lesions) at Kyoto University Hospital between January 2004 and April 2019. The prescribed dose was basically ≥70 Gy for the prostate with or without whole pelvic irradiation, and ≥45 Gy for the metastatic lesions. Clinical outcomes were compared with a contemporary cohort of 55 synchronous oligometastatic prostate cancer patients treated with the standard of care.

RESULTS

In total, 16 consecutive patients with synchronous oligometastatic prostate cancer were analyzed. The median follow-up period was 7.4 years. The 8-year overall survival, prostate cancer-specific survival, biochemical failure-free, clinical failure-free and castration-resistant prostate cancer-free rates were 64.8%, 71.3%, 38.5%, 47.3% and 67.3%, respectively. No grade 3 or higher radiation-induced late toxicities occurred. Patients with prostate-targeted treatment plus metastasis-directed therapy had a significantly higher castration-resistant prostate cancer-free rate than those without prostate-targeted treatment plus metastasis-directed therapy (P = 0.00741).

CONCLUSIONS

Prostate-targeted treatment plus metastasis-directed therapy through external beam radiation therapy can result in favorable long-term disease-free and survival outcomes with acceptable morbidities among synchronous oligometastatic prostate cancer patients. Therefore, this approach may represent a promising treatment strategy for this population. Further investigation is required.

Metastasis-Directed Radiotherapy for Oligometastatic Castration-Resistant Prostate Cancer

The treatment effects of metastasis-directed therapy in patients with oligometastatic disease have received much attention. In our case, a 72-year-old man with oligometastatic castration-resistant prostate cancer was referred to our hospital. The patient had undergone radical radiotherapy with a total dose of 76 Gy in 36 fractions for localized prostate cancer nine years prior to the first visit. Positron emission tomography showed a slight increase in accumulation in the para-aortic lymph nodes. The patient received conventional radiotherapy at a total dose of 50 Gy in 25 fractions to the para-aortic region as oligometastasis-directed local therapy. After radiotherapy, his prostate-specific antigen (PSA) level decreased slightly, but it increased again soon after. According to the results of positron emission tomography, the accumulation around the para-aortic lymph nodes had decreased; however, a slight increase in accumulation in the sub/supra-clavicular lymph nodes was observed. He received radiotherapy at a total dose of 50 Gy in 25 fractions to the sub/supra-clavicular region. We confirmed a significant reduction in lesion volume and a downward trend in PSA levels.

Metastasis-directed therapy has shown remarkable effectiveness in controlling disease without severe treatment-related adverse events. Metastasis-directed therapy is considered as one of the treatment options in patients who need salvage therapy.

Oncological Outcome of Combining Cytoreductive Prostatectomy and Metastasis-Directed Radiotherapy in Patients with Prostate Cancer and Bone Oligometastases: A Retrospective Cohort Study

Background

The current standard of care for metastatic prostate cancer (mPCa) is androgen deprivation therapy (ADT) with or without anti-androgen and chemotherapy. The aim of this study was to evaluate the efficacy and safety of a multimodal approach including local primary tumor therapy, metastasis-directed therapy (MDT), and hormonal therapy in patients with oligometastatic prostate cancer (PCa).

Methods

We reviewed data of patients with PCa and bone oligometastases at diagnosis treated in three institutions with ADT followed by cytoreductive surgery with or without metastases-directed radiotherapy. Oligometastases were defined as the presence of five or fewer metastatic lesions with the absence of visceral metastases. In this retrospective cohort study, 58 patients underwent cytoreductive radical prostatectomy and ADT. Of these, 26 patients (45%) received stereotactic body radiation therapy (SBRT) to all metastatic sites as a MDT. Oncological outcomes were analyzed using the Kaplan–Meier method.

Results

The median follow-up period was 46.2 months. Of the 58 patients, the 3-year castration-resistant prostate cancer (CRPC)-free survival and cancer-specific survival was 75.9% and 91.4%, respectively. Pre- or post-treatment predictive factors for progression to CRPC, including prostate-specific antigen (PSA) level at diagnosis ≥20 ng/mL, Gleason grade groups 5, clinical T stage cT3b-4, PSA nadir level of ≥0.05 ng/mL, and no MDT with SBRT, were significantly associated with progression to CRPC. Subgroup analysis showed that the MDT group had significantly better CRPC-free survival than the non-MDT group with Gleason grade groups 1–4 (HR=0.228; 95% CI= 0.056–0.926). A total of 3.4% of the patients had grade 2 acute genitourinary toxicities and 5.2% had grade 2 acute gastrointestinal toxicities. No late grade >2 adverse events were observed.

Conclusion

This multi-center, retrospective cohort study revealed the feasibility of combining cytoreductive prostatectomy and metastasis-directed radiotherapy for newly-diagnosed oligometastatic PCa. This treatment strategy has the potential to delay the progression to CRPC.

Long-term clinical outcomes of salvage pelvic radiation therapy for oligo-recurrent pelvic lymph nodes after definitive external-beam radiation therapy for non-metastatic prostate cancer

Although salvage external-beam radiation therapy (EBRT) is an attractive treatment option for pelvic lymph nodal recurrence (PeNR) in patients with prostate cancer (PCa), limited data are available regarding its long-term efficacy. This study examined the long-term clinical outcomes of patients who underwent salvage pelvic radiation therapy (sPRT) for oligo-recurrent pelvic lymph nodes after definitive EBRT for non-metastatic PCa. Patients who developed PeNR after definitive EBRT and were subsequently treated with sPRT at our institution between November 2007 and December 2015 were retrospectively analyzed. The prescribed dose was 45-50.4 Gy (1.8-2 Gy per fraction) to the upper pelvis, with up to 54-66 Gy (1.8-2 Gy per fraction) for recurrent nodes. Long-term hormonal therapy was used as neoadjuvant and/or adjuvant therapy. The study population consisted of 12 consecutive patients with PeNR after definitive EBRT (median age: 73 years). The median follow-up period was 58.9 months. The 5-year overall survival, PCa-specific survival, biochemical failure-free, clinical failure-free, and castration-resistant PCa-free rates were 82.5, 100.0, 62.3, 81.8, and 81.8%, respectively. No grade 2 or higher sPRT-related late toxicities occurred. In conclusion, more than half of the study patients treated with sPRT had a long-term disease-free status with acceptable morbidities. Moreover, most of the patients maintained hormonal sensitivity. Therefore, this approach may be a promising treatment method for oligo-recurrent pelvic lymph nodes.

A Trial-Based Cost-Utility Analysis of Metastasis-Directed Therapy for Oligorecurrent Prostate Cancer

The optimal management of patients with oligorecurrent prostate cancer (PCa) is unknown. There is growing interest in metastasis-directed therapy (MDT) for this population. The objective was to assess cost-utility from a Belgian healthcare payer’s perspective of MDT and delayed androgen deprivation therapy (ADT) in comparison with surveillance and delayed ADT, and with immediate ADT. A Markov decision-analytic trial-based model was developed, projecting the results over a 5-year time horizon with one-month cycles. Clinical data were derived from the STOMP trial and literature. Treatment costs were derived from official government documents. Probabilistic sensitivity analyses showed that MDT is cost-effective compared to surveillance (ICER: €8393/quality adjusted life year (QALY)) and immediate ADT (dominant strategy). The ICER is most sensitive to utilities in the different health states and the first month MDT cost. At a willingness-to-pay threshold of €40,000 per QALY, the cost of the first month MDT should not exceed €8136 to be cost-effective compared to surveillance. The Markov-model suggests that MDT for oligorecurrent PCa is potentially cost-effective in comparison with surveillance and delayed ADT, and in comparison with immediate ADT.

The role of hormone therapy and chemotherapy in oligometastatic prostate cancer

Oligometastatic disease was proposed by Hellman and Weichselbaum in 1995 as an intermediate tumour state between localised lesions and widespread metastases, characterised by the limited number and size of metastases in specific organs such as lung, liver, bone or even brain. The oligometastatic state has increasingly been recognised as a unique clinical state during which local ablative treatment can be effective in several types of cancer, including prostate cancer. However, the role of systemic therapy, such as hormone therapy and chemotherapy, is not yet well known. Some promising data for local ablative therapy have emerged, but it remains unclear whether local therapy can eliminate the need for, androgen-deprivation therapy (ADT), or reduce the required duration. In addition, several randomised phase III trials have demonstrated survival benefits from the addition of docetaxel or abiraterone to ADT in patients with metastatic hormone-sensitive prostate cancer. These findings suggest that such aggressive treatments may improve clinical outcomes for patients with oligometastatic prostate cancer. However, the efficacy of these treatments may depend on the volume of metastases, with higher efficacy for high-volume disease. Therefore, further investigation including stratification by disease volume is warranted. This review will discuss the current evidence and controversies surrounding the role of systemic therapy in patients with oligometastatic prostate cancer.

Salvage Pelvic Lymph Node Dissection After Fluciclovine Positron Emission Tomography/Computed Tomography Detected Prostate Cancer Recurrence

Background: Multiple new systemic agents have been targeted to metastatic prostate cancer, with decreased progression of disease but no cure. Surgical management of metastatic disease has been gaining interest, primarily in the setting of high-risk prostatectomies. However, metastasis-directed surgical intervention has been employed in rare scenarios, especially in oligometastatic disease. We report here on a salvage robot-assisted pelvic lymph node dissection for a solitary metastatic site.

Case Presentation: A 63-year-old Hispanic man who was initially treated with prostatectomy for intermediate risk cancer developed rapid biochemical recurrence. After salvage radiation, fluciclovine positron emission tomography (PET)/computed tomography (CT) scan showed a solitary pelvic lymph node metastasis. A robot-assisted laparoscopic pelvic lymph node dissection was carried out, with subsequent nadir of his prostate-specific antigen at 0.026.

Conclusion: To our knowledge, this is the first report of salvage pelvic lymph node dissection after metastatic detection by fluciclovine PET/CT scan. Our patient experienced a complete biochemical response; however, it remains to be seen whether this will be a lasting response. Surgical resection of metastatic sites in prostate cancer offers a safe alternative to systemic therapy and avoids systemic side effects.

Perspective on cytoreduction and metastasis-directed therapy in node positive and metastatic urothelial carcinoma of the bladder

The outcome of node positive or metastatic urothelial carcinoma of the bladder (mUCB) is poor and palliative chemotherapy has long been considered the only treatment option for this patient group. Cytoreduction and metastasis-directed therapy, either by surgery or radiotherapy, has been successfully applied in other metastatic solid tumors in order to increase survival. In this article, we explore the literature supporting cytoreduction and metastasis-directed therapy in node positive and mUCB and try to define a patient cohort that could benefit from these treatments. From these data, it is clear that a selected group of patients survive a long time or could even be cured, however the data are scarce and the level of evidence is low. The criteria of a randomized clinical trial, to deliver the necessary evidence, are proposed.