Oligometastases from prostate cancer: local treatment with stereotactic body radiotherapy (SBRT)

Current Treatment Paradigms and Clinical Outcomes in Oligometastatic Prostate Cancer Patients: A Targeted Literature Review

CONTEXT

Prostate cancer is the most common noncutaneous malignancy among men in the USA and Europe. There is no consensus definition of oligometastatic prostate cancer (omPC), which is often considered in two subgroups, synchronous (de novo) and metachronous (oligorecurrent), and may include patients with a low metastatic disease burden.

OBJECTIVE

To summarize the epidemiology, disease definitions, mortality/survival outcomes, and treatment characteristics in both clinical trial and real-world settings among patients with synchronous, metachronous, and mixed-subtype (ie, synchronous and metachronous or undefined type) omPC, as well as low burden disease states.

EVIDENCE ACQUISITION

We searched MEDLINE and Embase to identify publications reporting on epidemiology, disease definitions, clinical outcomes, and treatment characteristics of omPC. Gray literature sources (eg, ClinicalTrials.gov) were searched for ongoing trials.

EVIDENCE SYNTHESIS

We identified 105 publications. Disease definitions varied across publications and omPC subtypes on the number and location of lesions, type of imaging used, and type of oligometastatic disease. Most studies defined omPC as five or fewer metastatic lesions. Data on the epidemiology of omPC were limited. Mortality rates and overall survival tended to be worse among synchronous versus metachronous omPC cohorts. Progression-free survival was generally longer among synchronous than among metachronous omPC cohorts but was more similar at longer time points. A summary of ongoing clinical trials investigating a variety of local, metastasis-directed, and systemic therapies in men with omPC is also provided.

CONCLUSIONS

Definitions of oligometastatic disease depend on the imaging technique used. Epidemiologic data for omPC are scarce. Survival rates differ between synchronous and metachronous cohorts, and heterogeneous treatment patterns result in varied outcomes. Ongoing clinical trials using modern imaging techniques are awaited and needed.

PATIENT SUMMARY

Definitions of oligometastatic prostate cancer (omPC) vary depending on the imaging technique used. Different treatment patterns lead to different outcomes. Robust omPC epidemiologic data are lacking.

Secondary cytoreduction surgery for recurrent epithelial ovarian cancer patients after PARPi maintenance: A multicenter, randomized, controlled clinical trial

BACKGROUND

Poly ADP-ribose polymerase inhibitors (PARPi) treatment has radically changed the treatment strategy for epithelial ovarian cancer. Cancer progression with PARPi maintenance is a new problem that has arisen in clinical practice, and the value of secondary cytoreduction surgery remains unknown.

PRIMARY OBJECTIVE

To evaluate the benefits of secondary cytoreductive surgery and to clarify the sensitivity to platinum in patients with firstline or secondline recurrent epithelial ovarian cancer who have completed ≥6 months of PARPi maintenance.

STUDY HYPOTHESIS

Carefully selected patients who progress on PARPi maintenance will benefit from secondary cytoreductive surgery.

TRIAL DESIGN

This is a multicenter phase III trial. Eligible patients will be randomly assigned at a ratio of 1:1 to either the experimental or standard arm. Patients in the experimental arm will receive secondary cytoreductive surgery followed by platinum based chemotherapy, while patients in the standard arm will be provided with chemotherapy alone.

MAJOR INCLUSION/EXCLUSION CRITERIA

Patients diagnosed with firstline or secondline recurrent epithelial ovarian cancer who had previously received ≥4 cycles of platinum based chemotherapy in initial treatment followed by PARPi maintenance therapy for ≥6 months prior to recurrence.

PRIMARY ENDPOINT

Progression free survival.

SAMPLE SIZE

400 patients.

ESTIMATED DATES FOR COMPETING ACCRUAL AND PRESENTING RESULTS

Accrual completion is expected in December 2024 with results mature after 2 years of follow-up in 2026.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05607329.

[18F]DCFPyL PET/CT versus [18F]fluoromethylcholine PET/CT in Biochemical Recurrence of Prostate Cancer (PYTHON): a prospective, open label, cross-over, comparative study

PURPOSE

Primary objective was to compare the per-patient detection rates (DR) of [18F]DCFPyL versus [18F]fluoromethylcholine positron emission tomography/computed tomography (PET/CT), in patients with first prostate cancer (PCa) biochemical recurrence (BCR). Secondary endpoints included safety and impact on patient management (PM).

METHODS

This was a prospective, open label, cross-over, comparative study with randomized treatment administration of [18F]DCFPyL (investigational medicinal product) or [18F]fluoromethylcholine (comparator). Men with rising prostate-specific antigen (PSA) after initial curative therapy were enrolled. [18F]DCFPyL and [18F]fluoromethylcholine PET/CTs were performed within a maximum time interval of 12 days. DR was defined as the percentage of positive PET/CT scans identified by 3 central imaging readers. PM was assessed by comparing the proposed pre-PET/CT treatment with the local treatment", defined after considering both PET/CTs.

RESULTS

A total of 205 patients with first BCR after radical prostatectomy (73%; median PSA = 0.46 ng/ml [CI 0.16;27.0]) or radiation therapy (27%; median PSA = 4.23 ng/ml [CI 1.4;98.6]) underwent [18F]DCFPyL- and/or [18F]fluoromethylcholine -PET/CTs, between July and December 2020, at 22 European sites. 201 patients completed the study. The per-patient DR was significantly higher for [18F]DCFPyL- compared to [18F]fluoromethylcholine -PET/CTs (58% (117/201 patients) vs. 40% (81/201 patients), p < 0.0001). DR increased with higher PSA values for both tracers (PSA ≤ 0.5 ng/ml: 26/74 (35%) vs. 22/74 (30%); PSA 0.5 to ≤ 1.0 ng/ml: 17/31 (55%) vs. 10/31 (32%); PSA 1.01 to < 2.0 ng/ml: 13/19 (68%) vs. 6/19 (32%);PSA > 2.0: 50/57 (88%) vs. 39/57 (68%) for [18F]DCFPyL- and [18F]fluoromethylcholine -PET/CT, respectively). [18F]DCFPyL PET/CT had an impact on PM in 44% (90/204) of patients versus 29% (58/202) for [18F]fluoromethylcholine. Overall, no drug-related nor serious adverse events were observed.

CONCLUSIONS

The primary endpoint of this study was achieved, confirming a significantly higher detection rate for [18F]DCFPyL compared to [18F]fluoromethylcholine, in men with first BCR of PCa, across a wide PSA range. [18F]DCFPyL was safe and well tolerated.

Outcomes of Patients With Spinal Metastases From Prostate Cancer Treated With Conventionally-Fractionated External Beam Radiation Therapy

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To evaluate the outcomes of conventionally-fractionated external beam radiation therapy (cEBRT) in the treatment of prostate cancer spinal metastases (PCSM).

METHODS

Patients who received palliative cEBRT for PCSM in our institution between 2008 and 2018 were included. Our outcomes were local progression-free survival (LPFS), overall survival (OS), pain response and toxicities graded using CTCAE version 4.03. Univariable and multivariable Cox proportional hazard regressions were performed to identify predictors for LPFS and OS.

RESULTS

A total of 100 patients with 132 sites of PCSM were identified, with a median follow-up of 54 months. Fourteen-percent of patients underwent surgical intervention before receiving cEBRT. Eighteen spinal segments (13.6%) had local progression, with a median time to local progression of 8 months. The median LPFS and OS were 7.8 and 9.0 months, respectively. The complete and partial pain response rates were 57% and 39% respectively. The incidence of grade ≥3 acute toxicities was 11%. Better ECOG performance status (0 to 1), castration-sensitive disease, spinal surgery and use of novel antiandrogen agent were identified as significant predictors for improved OS on multivariable analysis.

CONCLUSIONS

In our prostate cancer cohort, cEBRT is an effective treatment modality for local palliation of spinal metastases. More aggressive treatment approach should be considered for patients with excellent performance status and castration-sensitive disease in light of their expected longer survival. Further studies are warranted to identify the predictors for radiotherapy response in this population.

Inhibition of CXCR4 Enhances the Efficacy of Radiotherapy in Metastatic Prostate Cancer Models

Radiotherapy (RT) is a standard treatment for patients with advanced prostate cancer (PCa). Previous preclinical studies showed that SDF1α/CXCR4 axis could mediate PCa metastasis (most often to the bones) and cancer resistance to RT. We found high levels of expression for both SDF1α and its receptor CXCR4 in primary and metastatic PCa tissue samples. In vitro analyses using PCa cells revealed an important role of CXCR4 in cell invasion but not radiotolerance. Pharmacologic inhibition of CXCR4 using AMD3100 showed no efficacy in orthotopic primary and bone metastatic PCa models. However, when combined with RT, AMD3100 potentiated the effect of local single-dose RT (12 Gy) in both models. Moreover, CXCR4 inhibition also reduced lymph node metastasis from primary PCa. Notably, CXCR4 inhibition promoted the normalization of bone metastatic PCa vasculature and reduced tissue hypoxia. In conclusion, the SDF1α/CXCR4 axis is a potential therapeutic target in metastatic PCa patients treated with RT.

Prognostic differences between oligometastatic and polymetastatic disease after resection in patients with colorectal cancer and hepatic or lung metastases: Retrospective analysis of a large cohort at a single institution

BACKGROUND

Long-term survival data are lacking, and prognostic factors are not well-defined for patients with colorectal cancer and hepatic or lung metastases. This study evaluated the outcomes after resection of oligometastatic hepatic or lung metastases from colorectal cancer and sought to identify prognostic factors.

METHODS

We retrospectively investigated 1,123 patients with colorectal cancer and hepatic or pulmonary metastases who underwent curative surgery between January 1991 and December 2016.

RESULTS

Of the 1,123 patients, 719 had hepatic metastases, 287 had pulmonary metastases, and 117 had both. The 5-year overall survival rate was 52.3% in the hepatic metastases group, 70.4% in the pulmonary metastases group, and 71.4% in the hepatic and pulmonary metastases group (P < .001). In total, 1,045 patients had oligometastases (1-5 metastatic lesions in 1 or 2 organs) and 78 had polymetastases (≥6 metastases in 1 or 2 organs). Prognosis was significantly better in patients with oligometastases than in those with polymetastases. The 5-year overall survival rate was 59.0% in the oligometastases group and 35.3% in the polymetastases group (P < .001); the respective 5-year relapse-free survival rates were 37.5% and 11.6% (P < .001). Multivariable analysis identified predictors of both poor overall survival and relapse-free survival to be a high carcinoembryonic antigen level before the first metastasectomy, largest metastasis measuring ≥2 cm, polymetastases, and synchronous metastases.

CONCLUSION

Prognosis after curative resection was better in patients with oligometastatic colorectal cancer in the liver or lung than in those with polymetastases. Multidisciplinary decision-making strategies, including about surgery, should be based on number of metastases rather than their site.

Using PSMA imaging for prognostication in localized and advanced prostate cancer

The use of prostate-specific membrane antigen (PSMA)-directed applications in modern prostate cancer management has evolved rapidly over the past few years, helping to establish new treatment pathways and provide further insights into prostate cancer biology. However, the prognostic implications of PSMA-PET have not been studied systematically, owing to rapid clinical implementation without long follow-up periods to determine intermediate-term and long-term oncological outcomes. Currently available data suggest that traditional prognostic factors and survival outcomes are associated with high PSMA expression (both according to immunohistochemistry and PET uptake) in men with localized and biochemically recurrent disease. Treatment with curative intent (primary and/or salvage) often fails when PSMA-positive metastases are present; however, the sensitivity of PSMA-PET in detecting all metastases is poor. Low PSMA-PET uptake in recurrent disease is a favourable prognostic factor; however, it can be associated with poor prognosis in conjunction with high ¹⁸F-fluorodeoxyglucose uptake in metastatic castration-resistant prostate cancer. Clinical trials embedding PSMA-PET for guiding management with reliable oncological outcomes are needed to support ongoing clinical use.

Oligometastatic Prostate Cancer: Current Status and Future Challenges

In accordance with the spectrum theory of metastatic disease, an oligometastatic clinical state has been proposed as an intermediary step along the natural history of cancer with few (typically 1-3) metastatic lesions identifiable on imaging that may be amenable to metastasis-directed therapy. Effective therapy of oligometastatic disease is anticipated to impact cancer evolution by delaying progression and improving patient outcome at a minimal or acceptable cost of toxicity. There has been increasing recognition of oligometastatic disease in prostate cancer with the advent of new-generation imaging agents, most notably the recently approved PET radiotracers based on targeting prostate-specific membrane antigen. Early clinical trials with metastasis-directed therapy of oligometastases have provided evidence for delaying the employment of systematic therapy and improving outcome in selected patients. Despite these encouraging results, much needs to be investigated and learned about the underlying biology of the oligometastatic state along the evolutionary clinical course of prostate cancer, the identification of relevant imaging and nonimaging predictive and prognostic biomarkers, and the development of treatment strategies to optimize short-term and long-term patient outcome. We provide a review of the current status and the lingering challenges of this rapidly evolving clinical space in prostate cancer.

Bone-only oligometastatic prostate cancer: can SABR improve outcomes? A single-center experience

Purpose

Ablative treatment of oligometastases has shown survival benefit with certain tumors, although these effects still are to be demonstrated in prostate cancer.

Materials and Methods

We analysed the toxicity and clinical control results obtained in patients with bone-only oligometastatic prostate cancer treated with stereotactic ablative radiotherapy (SABR). Retrospective study on patients with metachronous oligoprogression and synchronous de novo bone-only oligometastatic prostate cancer treated with SABR and androgen deprivation therapy.

Results

Treatment schedules varied according to location and organs at risk, with biologically equivalent dose (BED) ≥100 Gy. Fifty-five bone lesions (31 patients) were treated and evaluated for toxicity, local control, progression-free survival (PFS), and overall survival (OS). After a 41-month follow-up, there was minimal acute or chronic toxicity and no G3 toxicity. The local control at 3 and 5 years was 100% and 87.1%, respectively. Median PFS and OS were 43 and 98 months, respectively. The best result in PFS was obtained with BED ≥230 Gy, delaying time to the next systemic therapy by 28.5 months.

Conclusion

The use of SABR in bone oligometastases of prostate cancer is safe with minimal toxicity and excellent results in local control and PFS, delaying the start of the next systemic therapy.

Nodal and osseous oligometastatic prostate cancer: a cohort including the introduction of PSMA-PET/CT-guided stereotactic and hypofractionated radiotherapy with elective nodal therapy

PURPOSE

Oligometastatic prostate cancer is heavily investigated, and conventionally fractionated elective nodal treatment appears to increase biochemical relapse-free (bRFS) survival. The novelty of this report is to present elective nodal radiotherapy (ENRT) with simultaneous integrated boost with stereotactic (SBRT) or hypofractionated radiotherapy (HoFRT) for tolerance and for bRFS which we compared with SBRT of the involved field (IF) only.

MATERIALS AND METHODS

Patients between 2018 and 2021 with and oligometastatic prostate cancer treated with SBRT or hypofractionation were eligible. A radiobiologically calculated simultaneous integrated boost approach enabled to encompass elective nodal radiotherapy (ENRT) with high doses to PSMA-positive nodes. A second group had only involved field (IF) nodal SBRT.

RESULTS

A total of 44 patients with 80 lesions of initially intermediate- (52%) or high-risk (48%) D'Amico omPC were treated with SBRT to all visible PSMA-PET/CT lesions and 100% of the treated lesions were locally controlled after a median follow-up was 18 months (range 3-42 months). Most lesions (56/80; 70%) were nodal and the remainder osseous. Median bPFS was 16 months and ADT-free bPFS 18 months. ENRT (31 patients) versus IF (13 patients) prevented regional relapse more successfully. At univariate analysis, both initial PSA and length of the interval between primary diagnosis and biochemical failure were significant for biochemical control. Treatment was well tolerated and only two patients had toxicity ≥ grade 3 (1 GU and 1 GI, each).

DISCUSSION/CONCLUSION

SBRT and hypofractionated radiotherapy at curative doses with ENRT was more effective to delay ADT than IF, controlled all treated lesions and was well tolerated.

Clinical application of radiotherapy in patients with oligometastatic ovarian cancer: a sharp tool to prolong the interval of systemic treatment

BACKGROUND

With the advances of radiation technology, treatment of oligometastatic disease, with limited metastatic burden, have more chances to achieve long-term local control. Here we aim to evaluate the efficacy and safety of radiotherapy (RT) in oligometastatic ovarian cancer patients.

METHODS

A retrospective analysis collecting 142 patients (189 lesions) with oligometastatic ovarian cancer were included in the study. All pateints received radiotherapy and the curative effect and response rate were evaluated by diagnostic imaging after 1-3 months of radiotherapy with RECIST. Endpoints were the rate of complete response (CR), chemotherapy-free interval (CFI), local control (LC) rate and overall survival (OS) rate. Toxicity was evaluated by the Radiation Therapy Oncology Group (RTOG). Logistic and Cox regression were used for the uni- and multivariate analysis of factors influencing survival outcomes.

RESULTS

From 2013.1.1 to 2020.12.30, a total of 142 ovarian cancer patients (189 oligometastasis lesions) were included in the analysis. Prescribed doses to an average GTV of 3.10 cm were 1.8-8 Gy/fraction, median BED (28-115, a/b = 10 Gy), 5-28 fractions. For 179 evaluable lesions, the cases of CR, partial response (PR), stable disease (SD) and progressive disease (PD) after radiotherapy were 22,39,38 and 80 respectively. The disease control rate (DCR): CR + PR + SD was 55.31%, and the objective response rate (ORR): CR + PR was 34.08%. No patient developed grade 3 or higher side effect. The median CFI was 14 months (1-99 months), and the LC rate was 69.7%, 54.3% and 40.9% in 1 year, 2 years and 5 years respectively. GTV < 3 cm before treatment, platinum sensitivity, time from the last treatment ≥ 6 months, single lesion and BED(a/b = 10 Gy) ≥ 60 are the factors of good LC (p < 0.05). The total OS of 1 year, 2 years and 5 years were 67.1%, 52.6% and 30.3%, respectively. Single lesion (HR 0.598, 95%CI 0.405-0.884), DCR (HR 0.640, 95% CI 0.448-0.918) and ORR(HR 0.466, 95% CI 0.308-0.707) were the significant factors influencing 5-year OS.

CONCLUSION

For patients with oligometastatic ovarian cancer, radiotherapy has high LC, long chemotherapy-free interval, and survival benefits. Subgroup analysis shows that patients with single lesion and good local treatment results have higher overall survival rate, suggesting that active treatment is also beneficial for oligometastatic ovarian cancer patients.

Radiotherapy in Oligometastatic Prostate Cancer

Prostate cancer ranges from localized, low risk to metastatic, morbid disease. While radiotherapy is commonly incorporated in the treatment of early disease or for palliation of symptomatic lesions, its role in extending survival in metastatic disease is less well-established. Here, we review the available evidence surrounding localized radiotherapy in the presence of oligometastatic disease and metastasis-directed therapy in both hormone-sensitive and hormone-resistant prostate cancer. We further outline potential future incorporation of radiotherapy as an immune-sensitizing therapy and the importance of highly sensitive imaging modalities in considering radiotherapy in metastatic disease.

Stereotactic radiosurgery for bone metastases in oligometastatic prostate cancer patients: DESTROY-2 clinical trial subanalysis

INTRODUCTION

Aim of this analysis was to report toxicity and clinical outcomes in oligorecurrent prostate cancer (PCa) patients treated with single fraction stereotactic radiosurgery (SRS) for bone metastases.

METHODS

We separately analyzed clinical data of PCa patients with bone oligometastases enrolled in a prospective phase I trial (DESTROY-2). DESTROY-2 was based on SRS delivered using volumetric modulated arc therapy in patients with primary or metastatic tumors in several extra-cranial body sites. Acute and late toxicity, biochemical tumor response, local control (LC), distant metastases-free (DPFS), progression-free (PFS), time to next-line systemic treatment-free (NEST-FS), and overall survival (OS) were calculated.

RESULTS

Data on 37 PCa patients, carrying out 50 bone metastases, candidates for curative-intent treatment and treated with SRS at our Institution were collected. SRS dose ranged between 12 and 24 Gy. One grade 1 acute skin toxicity in one patient treated on the hip (24 Gy) and one grade 1 late skin toxicity in a patient with a scapular lesion (24 Gy) were recorded. No cases of bone fracture were registered in the treated population. With a median follow-up of 25 months (range 3-72 months) 2-year actuarial LC, DPFS, PFS, and OS were 96.7%, 58.1%, 58.1%, and 95.8%, respectively. Median and 2-year NEST-FS were 30 months (range 1-69 months) and 51.2%, respectively.

CONCLUSIONS

Data analysis showed few toxicity events, high local control rate and prolonged NEST-FS after linear accelerator-based radiosurgery of bone oligometastases from PCa. The possibility of postponing systemic treatments in patients with oligometastatic PCa by means of SRS should be taken into account. Further prospective studies on larger series are needed to confirm the reported results.

Spine Stereotactic Body Radiotherapy for Prostate Cancer Metastases and the Impact of Hormone Sensitivity Status on Local Control

BACKGROUND

Stereotactic body radiotherapy (SBRT) is used to deliver ablative dose of radiation to spinal metastases.

OBJECTIVE

To report the first dedicated series of spine SBRT specific to prostate cancer (PCa) metastases with outcomes reported according to hormone sensitivity status.

METHODS

A prospective database was reviewed identifying patients with PCa treated with spine SBRT. This included those with hormone-sensitive PCa (HSPC) and castrate-resistant PCa (CRPC). The primary end point was MRI-based local control (LC).

RESULTS

A total of 183 spine segments in 93 patients were identified; 146 segments had no prior radiation and 37 had been previously radiated; 27 segments were postoperative. The median follow-up was 31 months. At the time of SBRT, 50 patients had HSPC and the remaining 43 had CRPC. The most common fractionation scheme was 24-28 Gy in 2 SBRT fractions (76%). LC rates at 1 and 2 years were 99% and 95% and 94% and 78% for the HSPC and CRPC cohorts, respectively. For patients treated with de novo SBRT, a higher risk of local failure was observed in patients with CRPC (P = .0425). The 1-year and 2-year overall survival rates were significantly longer at 98% and 95% in the HSPC cohort compared with 79% and 65% in the CRPC cohort (P = .0005). The cumulative risk of vertebral compression fracture at 2 years was 10%.

CONCLUSION

Favorable LC rates were observed after spine SBRT for PCa metastases; strategies to improve long-term LC in patients with CRPC require further investigation.

Local control of 1-5 fraction radiotherapy regimens for spinal metastases: an analysis of the impacts of biologically effective dose and primary histology

BACKGROUND

This analysis evaluates the impacts of biologically effective dose (BED) and histology on local control (LC) of spinal metastases treated with highly conformal radiotherapy to moderately-escalated doses.

MATERIALS AND METHODS

Patients were treated at two institutions from 2010-2020. Treatments with less than 5 Gy per fraction or 8 Gy in 1 fraction were excluded. The dataset was divided into three RPA classes predictive of survival (1). The primary endpoint was LC.

RESULTS

223 patients with 248 treatments met inclusion criteria. Patients had a median Karnofsky Performance Status (KPS ) of 80, and common histologies included breast (29.4%), non-small cell lung cancer (15.7%), and prostate (13.3%). A median 24 Gy was delivered in 3 fractions (BED: 38.4 Gy) to a median planning target volume (PTV) of 37.3 cc. 2-year LC was 75.7%, and 2-year OS was 42.1%. Increased BED was predictive of improved LC for primary prostate cancer (HR = 0.85, 95% CI: 0.74-0.99). Patients with favorable survival (RPA class 1) had improved LC with BED ≥ 40 Gy (p = 0.05), unlike the intermediate and poor survival groups. No grade 3-5 toxicities were reported.

CONCLUSIONS

Moderately-escalated treatments were efficacious and well-tolerated. BED ≥ 40 Gy may improve LC, particularly for prostate cancer and patients with favorable survival.

[Stereotactic body radiation therapy for non-spine bone oligometastatic disease]

PURPOSE

Stereotaxic radiotherapy is performed regularly for the irradiation of non-spine bone metastases, but its place is not well understood.

MATERIALS AND METHODS

This article in stereotaxic radiotherapy of non-spine bones oligometastases presents the current scientific data relating to the indications, to virtual simulation, to the delineation of target volumes, to the total dose and fractionation, to the efficacy and tolerance.

RESULTS

Oligometastatic patients are classified into 4 categories: oligorecurrences, oligometastasis, oligopersistence, oligoprogression. The prognosis will be evaluated according to the following characteristics: primary tumor, quantitative characteristics, kinetics, qualitative characteristics. The delineation of GTV includes extensions to the soft tissue and bone marrow with the aid of MRI and PET. The CTV corresponds to a margin of 2 to 5mm and the PTV to a margin of 2mm. The most widely used irradiation schemes are: 1 single fraction of 18 to 24Gy/1 fr; 24Gy/2 fr; 27 to 30Gy/3 fr; 30 to 35Gy/5 fr. Stereotaxis provides 90% local control at 1 year and good pain control. The side effects are not very marked.

CONCLUSION

Stereotaxic radiotherapy is feasible, non-invasive, minimally toxic and effective with good local control and good pain relief. The main issue remains selecting the patients most likely to benefit from it.

SEOR SBRT-SG stereotactic body radiation therapy consensus guidelines for non-spine bone metastasis

The use of stereotactic body radiation therapy (SBRT) to treat non-spine bone metastases (NSBM) is becoming increasingly common in clinical practice. The clinical advantages of SBRT include good pain control and high local control rates, although only limited data are available. The Spanish Society of Radiation Oncology (SEOR) SBRT group recently convened a task force of experts in the field to address key questions related to SBRT for NSBM, including treatment indications, planning, techniques, and dose fractionation. The task force reviewed the available literature to develop evidence-based recommendations for the safe application of NSBM SBRT and to standardize and optimize SBRT processes. The present document provides a comprehensive analysis of the available data, including ongoing clinical trials and controversies, providing clinically applicable recommendations.

Long-Lasting Palliation of Bone Oligometastatic Prostate Cancer After Repeated Stereotactic Body Radiotherapy

Background: Oligometastatic disease has emerged as a distinct clinical state, with a tumor burden intermediate between localized and extensive systemic disease. Oligometastatic prostate cancer has generally been classified as ≤3 metastases in bone or lymph nodes only. Improvements in diagnostic modalities such as functional imaging allow a greater frequency of oligometastases diagnosis. Selected bone oligometastatic prostate cancer patients can be treated with metastasis-directed stereotactic body radiotherapy (SBRT) rather than androgen deprivation therapy (ADT). We describe a case representative of this scenario.

Case Report: A 72-year-old male underwent surgery and salvage radiotherapy for a Gleason score 7 (3+4) adenocarcinoma confined in the prostate but with microscopic-positive surgical margins. Eight months after the end of radiotherapy, bone metastasis was diagnosed and treated with SBRT only because the patient refused ADT. In the subsequent 10 years, 6 more courses of SBRT were administered for new bone oligometastases encountered during follow-up. Neither local recurrence nor toxicity was observed after SBRT treatments. The patient, who is now 83 years old, has a Karnofsky Performance Status score of 90% and has preserved a satisfactory potentia coeundi.

Conclusion: SBRT is a promising treatment for patients with bone oligometastatic prostate cancer, providing a high control rate within the irradiated volume and low toxicity. The ability to administer consecutive SBRT courses when new bone oligometastases are encountered in other sites can delay initiation of ADT. This case report reflects emerging trends for bone oligometastases treatment with metastasis-directed radiotherapy.

Outcomes of metastasis-directed therapy of bone oligometastatic prostate cancer

Background

The aim of this work was to investigate the outcome of metastasis-directed radiotherapy (MDT) in prostate cancer patients with bone metastases following current ESTRO/EORTC subclassifications for oligometastatic disease.

Methods

Clinical data of 80 consecutive oligometastatic patients with 115 bone lesions receiving MDT between 2011 and 2019 were retrospectively evaluated. Hormone-sensitive (77.5%) and castrate-resistant (22.5%) patients were included. MDT was delivered with conventional fractionated or stereotactic body radiotherapy (SBRT) techniques. Kaplan–Meier method, log rank test, as well as Cox regression were used to calculate local control (LC) and biochemical and clinical progression-free survival (bPFS/cPFS).

Results

At the time of MDT 31% of patients had de-novo synchronous oligometastatic disease, 46% had de-novo metachronous oligorecurrence after primary treatment and 23% had either de-novo oligoprogressive disease, repeat oligometastatic disease or induced oligometastatic disease. The median BED₃ was 93.3 Gy (range 75.8–95.3 Gy). Concomitant ADT was administered in 69% of patients. After a median follow-up of 23 months the median bPFS and cPFS were 16.5 and 21.5 months, respectively. The 2-year LC rate was 98.3%. In multivariate analysis, age ≤ 70 (HR = 2.60, 95% CI 1.20–5.62, p = 0.015) and concomitant ADT (HR = 0.26, 95% CI 0.12–0.58, p = 0.001) significantly correlated with cPFS. Category of oligometastatic disease and hormone-sensitivity were predictive for cPFS in univariate analysis. Of 45 patients with biochemical relapse, nineteen patients (42.2%) had repeat oligometastatic disease. Fourteen patients (31%) underwent a second course of MDT. No patients experienced grade ≥ 3 toxicities.

Conclusions

MDT is safe and offers high local control rates in bone oligometastases of prostate cancer. At 2 years after treatment, more than 2 out of 5 patients are progression-free.

Trial registration Retrospectively registered.

Oligometastatic Bone Disease in Castration-Sensitive Prostate Cancer Patients Treated With Stereotactic Body Radiotherapy Using 68Ga-PSMA PET/CT: TROD 09-004 Study

PURPOSE

To evaluate the outcomes of metastasis-directed treatment (MDT) using stereotactic body radiotherapy (SBRT) for bone-only oligometastasis (OM) detected with gallium prostate-specific membrane antigen (68Ga-PSMA) PET/CT in castration-sensitive prostate cancer (PC) patients.

METHODS

In this multi-institutional study, clinical data of 74 PC patients with 153 bone lesions who were undergoing MDT were retrospectively evaluated. Twenty-seven patients (36.5%) had synchronous, and 47 (63.5%) had metachronous OM. All patients had PC with 5 metastases or fewer detected by 68Ga-PSMA PET/CT and treated using SBRT with a median dose of 20 Gy. The prognostic factors for PC-specific survival (PCSS) and progression-free survival (PFS) were analyzed.

RESULTS

The median follow-up was 27.3 months. Patients with synchronous OM were older and received higher rates of androgen deprivation therapy after SBRT compared with patients with metachronous OM. The 2-year PCSS and PFS rates were 92.0% and 72.0%, respectively. A prostate-specific antigen (PSA) decline was observed in 56 patients (75.7%), and 48 (64.9%) had a PSA response defined as at least 25% decrease of PSA after MDT. The 2-year local control rate per lesion was 95.4%. In multivariate analysis, single OM and PSA response after MDT were significant predictors for better PCSS and PFS. In-field recurrence was observed in 4 patients (6.5%) with 10 lesions at a median of 13.1 months after MDT completion. No serious late toxicity was observed.

CONCLUSIONS

We demonstrated that SBRT is an efficient and well-tolerated treatment option for PC patients with 5 bone-only oligometastases or fewer detected with 68Ga-PSMA PET/CT.

Radiotherapy of oligometastatic prostate cancer: a systematic review

BACKGROUND

Due to improved imaging sensitivity, the term "oligometastatic" prostate cancer disease is diagnosed more often, leading to an increasing interest in metastasis-directed therapy (MDT). There are two types of radiation based MDT applied when treating oligometastatic disease: (1) stereotactic body radiation therapy (SBRT) generally used for bone metastases; or (2) SBRT for isolated nodal oligometastases combined with prophylactic elective nodal radiotherapy. This review aims to summarize current evidence data, which may shed light on the optimal management of this heterogeneous group of patients.

METHODS

A systematic review of the Medline database through PubMed was performed according to PRISMA guidelines. All relevant studies published up to November 2020 were identified and screened. Fifty-six titles were included. Besides outcome parameters, different prognostic and predictive factors were assessed, including site of metastases, time between primary treatment and MDT, use of systemic therapies, hormone sensitivity, as well as pattern of recurrence.

FINDINGS

Evidence consists largely of retrospective case series and no consistent precise definition of oligometastasis exists, however, most investigators seem to acknowledge the need to distinguish between patients presenting with what is frequently called "synchronous" versus "metachronous" oligometastatic disease. Available data on radiotherapy as MDT demonstrate high local control rates and a small but relevant proportion of patients without progressive disease after 2 years. This holds true for both hormone sensitive and castration resistant prostate cancer diseases. The use of 68Ga-PSMA PET/CT for staging increased dramatically. Radiation doses and field sizes varied considerably among the studies. The search for relevant prognostic and predictive factors is ongoing.

CONCLUSIONS

To our best knowledge this review on oligometastatic prostate cancer included the largest number of original articles. It demonstrates the therapeutic potential and challenges of MDT for oligometastatic prostate cancer. Prospective studies are under way and will provide further high-level evidence.

Positron Emission Tomography and Whole-body Magnetic Resonance Imaging for Metastasis-directed Therapy in Hormone-sensitive Oligometastatic Prostate Cancer After Primary Radical Treatment: A Systematic Review

CONTEXT

Next-generation imaging includes positron emission tomography (PET) imaging and whole-body magnetic resonance imaging (wbMRI) including diffusion-weighted imaging. Accurate quantification of oligometastatic disease using next-generation imaging is important to define the role and value of metastasis-directed therapy (MDT).

OBJECTIVE

To perform a review of next-generation imaging modalities in the detection of recurrent oligometastatic hormone-sensitive prostate cancer in men who received prior radical treatment for localized disease.

EVIDENCE ACQUISITION

MEDLINE, Scopus, Cochrane Libraries, and Web of Science databases were systematically searched for studies reporting next-generation imaging and oncological outcomes. An expert panel of urologists, radiation oncologists, radiologists, and nuclear medicine physicians performed a nonsystematic review of strengths and limitations of currently available imaging options for detecting the presence and extent of recurrent oligometastatic disease.

EVIDENCE SYNTHESIS

From 370 articles identified, three clinical trials and 21 observational studies met the following inclusion criteria: metachronous oligometastatic recurrence after radical treatment for prostate cancer, MDT, and hormone-sensitive patients. Androgen deprivation therapy (ADT) was allowed before MDT. Next-generation imaging modalities included PET/computed tomography and/or PET/MRI with the following tracers: choline (n = 1), NaF (n = 1), and prostate-specific membrane antigen (PSMA; n = 1) for clinical trials; choline (n = 7) or PSMA (n = 11) or both (n = 3) for observational studies. The number of metastases ranged from two to five lesions in most studies. In PSMA-based studies, progression-free survival ranged from 19% to 100%, whereas in studies employing choline, progression-free survival ranged from 16% to 93%. Overall, ADT-free survival ranged from 48% to 79%, while local control was reported as 75-100% and prostate-specific antigen response as 23-94%. Among the different PET tracers and wbMRI, PSMA PET is emerging as the most accurate imaging technique in defining the oligometastatic status.

CONCLUSIONS

PSMA and choline PET contribute to guiding MDT in men with hormone-sensitive oligometastatic prostate cancer. Further studies are warranted to ascertain their role and optimize the timing of imaging for such patients.

PATIENT SUMMARY

We looked at the evidence regarding the use of modern imaging techniques to direct additional treatments in men with early spread of prostate cancer after they receive their initial radical treatment. We found that next-generation imaging, in particular prostate-specific membrane antigen and choline positron emission tomography, can successfully guide metastasis-directed therapies, and further trials should evaluate which modalities are best suited to improve outcomes for our patients.

Role of 18F-Fluciclovine and Prostate-Specific Membrane Antigen PET/CT in Guiding Management of Oligometastatic Prostate Cancer: AJR Expert Panel Narrative Review

Twenty-five years ago, oligometastatic disease was proposed as an intermediary clinical state of cancer with unique implications for therapies that may impact cancer evolution and patient outcome. Identification of limited metastases that are potentially amenable to targeted therapies fundamentally depends on the sensitivity of diagnostic tools, including new-generation imaging methods. For men with biochemical recurrence after definitive therapy of the primary prostate cancer, PET/CT using either the FDA-approved radiolabeled amino acid analogue ¹⁸F-fluciclovine or investigational radiolabeled agents targeting prostate-specific membrane antigen (PSMA) enables identification of early metastases at lower serum PSA levels than was previously feasible using conventional imaging. Evidence supports PSMA PET/CT as the most sensitive imaging modality available for identifying disease sites in oligometastatic prostate cancer. PSMA PET/CT will likely become the modality of choice after regulatory approval and will drive the development of trials of emerging metastasis-directed therapies such as stereotactic ablative body radiation and radioguided surgery. Indeed, numerous ongoing or planned clinical trials are studying advances in management of oligometastatic prostate cancer based on this heightened diagnostic capacity. In this rapidly evolving clinical environment, radiologists and nuclear medicine physicians will play major roles in facilitating clinical decision making and management of patients with oligometastatic prostate cancer.

External beam radiotherapy for prostate cancer: What are the current research trends and hotspots?

Background

The external beam radiotherapy (EBRT) applied for prostate cancer (PCa) has been one of the most important and hottest research fields over recent decades. This study aimed to explore the research hotspots of EBRT in PCa and help the researchers have a clear and intuitive reference basis for later researches.

Methods

The literature scientometric analysis related to “EBRT applied for PCa” was conducted via the Web of Science Core Collection from 2010 to 2019. The Microsoft Office Excel 2019 and CiteSpace V. 5.7.R1 software were introduced for visualizing and analyzing the data.

Results

A total of 7860 relevant papers were extracted and downloaded. A total of 7828 papers were extracted and analyzed after data cleansing by CiteSpace. The tendency of published papers was comprehensively increasing from 2010 to 2019. Among all 73 countries/regions, USA published the most papers, accounting for 39%, which was the most active contributor with most publications. Australia (Centrality: 0.18), England (Centrality: 0.12) were cooperating most cohesively with other countries. Univ Toronto was the most productive institute (229), while Harvard Univ (Centrality: 0.67) had extensive collaborations with other institutes. The International journal of Radiation Oncology Biology Physics had the largest number of publications and the highest number of co‐citations. Briganti A had the largest volume of publications. D'Amico AV had the highest number of co‐citations. Four latest and largest clusters were identified as oligometastases, salvage therapy (SRT), prostate‐specific membrane antigen (PSMA), and hypofractionation. Thirteen references became strongest burst citations lasting until 2019. The studies of “oligometastases,” “SRT,” “PSMA,” “hypofractionation,” “postoperative radiotherapy,” and “dose and fraction regimen changes” were prevailing in the recent years.

Conclusion

The “oligometastases,” “SRT,” “PSMA,” “hypofractionation,” “postoperative radiotherapy,” and “dose and fraction regimen changes” may be the state‐of‐art research frontiers, and related studies will advance in this field over time.

SBRT in non-spine bone metastases: a literature review

Stereotactic Body Radiotherapy (SBRT) is a technique for delivering high doses of radiation to tumors while preserving the normal tissues located around this area. Bone metastases are frequent in cancer patients. They can be distressingly painful or may cause pathological fractures. Radiation therapy is a fundamental aspect of treatment for bone metastases. The objective of this study is to analyze the literature on non-spine bone metastasis treated with SBRT, including immobilization, volume delineation, dose and fractionation, local control, side effects, and assessment of response after treatment. Full-text articles written in English language and published in the last 10 years were included in this review and were accessible on PubMed and MEDLINE. We examined 78 articles. A total of 40 studies were included in this review. Most were retrospective studies. The articles included were evaluated for content and validation. The immobilization systems and imaging tests used for tumor delimitation were variable between studies. The use of CTV (Clinical Target Volume) has not been defined. Doses and fractions were variable from 15 to 24 Gy/1 fraction to 24-50 Gy in 3-5 fractions, with local control being around 90% with a low rate of side effects. We review state of the art in SBRT non-spine metastases. SBRT can result in better local control and pain management in non-spine bone metastases patients. We need more research in volume delineation determining whether or not to use CTV and the role of MRI in volume contouring, optimal doses, and fractionation according to histology and a reliable response assessment tool. Studies that compare SBRT to conventional radiotherapy in local control and pain control are needed.

Local and metastatic curative radiotherapy in patients with de novo oligometastatic prostate cancer

The aim of this observational study is to investigate whether local consolidative treatment delivered to the primary site and metastatic tumour burden may add survival benefit to de novo oligometastatic prostate cancer (Oligo-PCa) patients. We retrospectively reviewed all Oligo-PCa patients treated with radiotherapy to the primary tumor sites and metastatic tumor burden at our institution between March 2010 and June 2019. All patients having ≤ 5 metastases involving nodes and/or bones, loco-regional and/or extra-pelvic sites, were included. Most of the patients had started androgen deprivation therapy with or without docetaxel as standard of care before radiotherapy. The Kaplan Meier analysis was performed to estimate survival outcomes. The univariate analysis tested possible prognostic factors increasing the rate of biochemical relapse. We analysed 37 Oligo-PCa patients. Twenty-eight (75.7%) had loco-regional metastases, in 9 patients (24.3%) the metastatic tumour burden was extra-pelvic. Nineteen (51.4%) had bone metastases, 21 (56.8%) nodal involvement and 7 (18.9%) both. Twenty (54.1%) had a single metastasis. The median follow-up was 55.5 months. The median overall survival (OS) was 68.8 months, the 2- and 5-year OS rates were 96.9% and 65.4%. The median biochemical relapse free survival (b-RFS) was 58 months and the 2- and 5-year b-RFS rates were 73.3% and 39.3%. The 2- and 5-year local relapse free survival rates were 93.9% and 83.7%. On the univariate analysis post-treatment PSA level ≤ 1 ng/ml was significantly related with the b-RFS (p = 0.004). Curative approach in Oligo-PCa patients involving both the primary tumor and metastatic sites may be feasible and well tolerate. Many patients presented longer survival and PSA at first follow-up was the most important prognostic factor. Further trials are needed to confirm our results and to evaluate if patients with PSA at first follow-up > 1 ng/ml may benefit from further treatments.

Metastasis-directed therapy and prostate-targeted therapy in oligometastatic prostate cancer: a systematic review

INTRODUCTION

The aim of this review was to summarize the available evidence on the role of metastasis-directed therapy (MDT) and/or prostate-targeted therapy (PTT) in the setting of oligometastatic prostate cancer (PCa).

EVIDENCE ACQUISITION

We searched PubMed, the Web of Science, and the Cochrane Library databases. The following keywords were used: ("prostate cancer" OR "prostate carcinoma" OR "prostate neoplasm" OR "prostate tumor") AND ("oligometastatic" OR "oligometastasis" OR "PSMA") AND ("surgery" OR "prostatectomy" OR "radical prostatectomy" OR "cytoreductive" OR "local treatment" OR "radiotherapy" OR "stereotactic" OR "stereotaxic") AND ("survival" OR "mortality").

EVIDENCE SYNTHESIS

After evaluating the selection criteria, 81 studies were evaluated for our endpoints. We included 22 studies for PTT of synchronous mPCa. There have been no randomized studies on cytoreductive prostatectomy (cRP). Four prospective studies showed that cRP was feasible but did not contribute to a positive effect on overall survival (OS). Regarding PTT-radiotherapy, two randomized controlled phase 3 trials showed that OS was improved in men with a low metastatic burden. Regarding MDT of metachronous lymph node recurrence, we included 29 retrospective studies. For MDT of oligometastases, we included 30 studies. One randomized phase 2 trial showed that androgen deprivation therapy-free survival improved with stereotactic body radiation therapy compared to that with surveillance; however, benefits on OS remain unclear.

CONCLUSIONS

We performed a comprehensive overview of the current literature on MDT and PTT. The feasibility of MDT and PTT is supported by several retrospective studies. Nevertheless, there remains a lack of high-quality trials to prove its survival benefits. Results from ongoing prospective trials data are awaited.

Single‐fraction image‐guided robotic radiosurgery efficiently controls local prostate cancer recurrence after radical prostatectomy

Purpose

To assess the therapeutic potential of single‐fraction robotic stereotactic ablative body radiotherapy (SABR) in patients with locally recurrent prostate cancer (PC) after radical prostatectomy (RP).

Materials and methods

We included 35 patients with biochemical failure after RP with single‐site local recurrence in the prostate bed diagnosed by PSMA PET/CT. About 20/35 pts had previously received post‐surgical adjuvant radiation therapy.

High‐resolution multiparametric magnetic resonance imaging (mpMRI) for exact visualization of tumor tissue was performed at 1.5 (n = 23; Siemens Magnetom Aera) or 3 Tesla (n = 12; Siemens Magnetom VIDA, Siemens Healthineers, Erlangen, Germany). Using the MRI and PET/CT dataset for planning, SABR was carried out after ultrasound‐guided placement of a single gold fiducial marker at the site of tumor recurrence using a CyberKnife M6 unit (Accuray Inc., Sunnyvale, USA). Due to the high diagnostic accuracy of PSMA PET/CT and mpMRI, pre‐SABR biopsy of tumor tissue was not deemed necessary. PSMA PET/CT performed in median 88 days before SABR confirmed the absence of distant metastases. MpMRI was performed at a median of 22 days prior to the intervention. SABR was performed in a single fraction with a dose of 20 (5/35), 21 (27/35) or 22 (3/35) Gy. Follow‐up serum PSA was measured every 3 months thereafter.

Results

Median patient age was 72 years (57‐80 years) and median time from RP to SABR was 96.8 months (IQR, 69.3‐160.2). Median serum PSA before SABR was 1.38 ng/mL (IQR 0.75‐2.72). At 3 months, median PSA had dropped significantly in 27/35 patients to a median of 0.35 ng/mL (IQR 0.25‐0.68). At 6 months, 30/35 patients showed biochemical response to SABR, while five patients were progressing: three had systemic disease on PSMA PET/CT, while two patients had rising PSA values without a visible correlate on PET/CT. The median follow‐up time was 16 months. Grade 1 genitourinary (GU) toxicity was reported in 3/35 patients (9%) and grade 1 gastrointestinal (GI) toxicity in 2/35 patients (6%), respectively.

Conclusion

SABR is an efficient new treatment option in the management of single‐site local recurrent PC without the evidence of systemic disease; due to its very low toxicity, it is an alternative to surgical re‐treatment or other focal therapies. It can significantly delay the onset of androgen deprivation therapy (ADT) in biochemical failure after radical prostatectomy.

Solitary rib lesions showing prostate-specific membrane antigen (PSMA) uptake in pre-treatment staging 68 Ga-PSMA-11 positron emission tomography scans for men with prostate cancer: benign or malignant?

OBJECTIVES

To determine the proportion of solitary rib lesions on pre-treatment ⁶⁸ Gallium-labelled prostate-specific membrane antigen (PSMA)/computed tomography (CT) scans in men with prostate cancer that are malignant and examine any predictive factors.

PATIENTS AND METHODS

This retrospective single tertiary referral institution cohort study of men reviewed the results of ⁶⁸ Ga-PSMA-11 positron emission tomography (PET)/CT scans performed for primary staging prior to treatment of prostate cancer from July 2014 to September 2019. Men with PSMA uptake outside the prostate in only the rib lesion were included. A solitary rib lesion was considered to be malignant if it increased in size on follow-up imaging. A lesion was considered benign if the prostate-specific antigen (PSA) level remained <0.1 µg/L following a radical prostatectomy (RP), <2 µg/L above nadir following radiotherapy (RT) as per the Phoenix criteria, histology was benign on rib biopsy, or follow-up imaging showed no growth of the rib lesion. If a lesion did not meet these criteria it was considered indeterminate.

RESULTS

A total of 62 men had PSMA uptake in a solitary rib lesion; 54 went on to have RPs and eight underwent RT. In all, 61 of the men (98.4%) met the criteria for a benign rib lesion. Only one man had a false-negative malignant lesion. This man had a rib lesion with a low maximum standardised uptake value (SUV_max ) of 2.21 reported as benign, but the postoperative PSA level was 0.67 µg/L and the rib lesion progressed on follow-up imaging, with development of widespread metastases. Of the benign rib lesions, there were four false positives reported as possible metastases. Three had percutaneous rib biopsies, two of which came back with benign histology and one was indeterminate. The indeterminate biopsy patient had a RP and his postoperative PSA level was <0.1 µg/L. A total of 43 (69.4%) men with benign rib lesions had a SUV_max greater than the SUV_max of the malignant lesion.

CONCLUSION

To our knowledge, this is the first cohort study of men with PSMA-avid solitary rib lesions on pre-treatment ⁶⁸ Ga-PSMA PET/CT staging scans for prostate cancer. Our results indicate that the vast majority of these lesions have low-intensity uptake and are benign. Intervention to confirm this is not usually required.

[Treatment concepts for primary oligometastatic prostate cancer]

BACKGROUND

About 5% of prostate cancer patients have distant metastases at diagnosis. In these metastatic hormone-sensitive prostate cancers (mHSPC), systemic therapy is recommended, according to the guidelines. Moreover, metastasis-directed therapy (MDT) is discussed to prolong survival.

OBJECTIVES

The contemporary literature concerning local therapy and MDT in patients with mHSPC is summarized.

METHODS

Selective literature search.

RESULTS

In 2018, randomized controlled data on local therapy in mHSPC patients were published by the authors of the STAMPEDE study. Here, patients were randomized between standard of care (SOC) ± radiotherapy to the prostate (RT). Within the overall cohort, no difference regarding 3‑year overall survival (OS) was observed. Within a prespecified subgroup of patients with low metastatic burden. Similar results were observed in numerous retrospective studies analyzing radical prostatectomy; prospective randomized studies are pending. For MDT, there are no sufficient data in mHSPC patients yet.

CONCLUSIONS

In the current guidelines, systematic therapy is standard of care in mHSPC patients. In patients with low metastatic burden, a survival benefit was observed when adding percutaneous RT to the prostate. Retrospective studies also suggest a benefit when adding RP. However, whether MDT prolongs survival is still unknown.

Randomized Pilot Study of 20 Gy in 5 Fractions versus 27 Gy in 3 Fractions Radiotherapy for Treating Painful Bone Metastases: A Single Institution Experience

Purpose:

Radiotherapy is a very effective tool in the treatment of painful bone metastases. The aim of this study was to compare the palliative effect of radiotherapy between the standard fractionation schedule 20 Gy over 5 fractions (20Gy/5fr) and the high biological dose schedule 27 Gy over 3 fractions (27Gy/3fr) which is frequently used in Stereotactic body radio-surgery (SBRT).

Methods:

Patients were randomized to receive (20Gy/5fr)or (27Gy/3fr). The primary aim of the study was pain relief using the numeric rating scale (NRS), after three months of radiation therapy. Secondary end points include pain relief immediately after finishing radiation therapy (within one week), and narcotic relief after three months of radiation therapy.

Results:

Twenty-two patients with painful bone metastases were included. 12 patients received (20Gy/5fr) and 10 patients received (27Gy/3fr). Male patients were predominant on both arms (81.8%) with a mean age of 58 years [ranging between 19-72 years]. For pain relief after three months of radiation therapy, partial pain relief was documented in 9 patients (75%) with (20Gy/5fr) and in 8 patients (80%) with (27Gy/3fr) with a p- value of 0.6. Additionally, narcotic relief after three months was equal for both groups. For immediate pain relief, partial pain relief was seen in one patient (8%) with (20Gy/5fr) versus seven patients (70%) with (27Gy/3fr) with a p value of 0.06. The increase in immediate pain relief in the 27Gy arm was numerically but not statistically significant.

Conclusion:

SBRT and standard fractionation radiation therapy had equal effectiveness for pain relief, when the assessment was done after three months of radiation therapy. Interestingly, SBRT had a better immediate pain relief.

Stereotactic body radiation therapy in the treatment of ovarian cancer

BACKGROUND

This study evaluates the outcomes and toxicity of stereotactic body radiation therapy (SBRT) in ovarian cancer.

METHODS

This retrospective analysis considered all patients treated with SBRT from 2009 to 2018 with a primary ovarian tumor. Follow-up included PET-CT and CT scans at 2-3 month intervals. Statistical analysis primarily consisted of univariate analysis, Cox proportional hazards analysis, and the Kaplan-Meier method.

RESULTS

The study included 35 patients with 98 treatments for lymph nodes (51), local recurrence (21), and de novo solid metastases (26). Median biologically effective dose (BED), gross tumor volume, and planning target volume were 38.40 Gy, 10.41 cc, and 25.21 cc, respectively. 52 lesions showed complete radiographic response, and two-year local control was 80%. Median overall survival (OS) was 35.2 months, and two-year progression-free survival (PFS) was 12%. On univariate analysis, Eastern Cooperative Oncology Group performance status > 0 was predictive of decreased OS (p = 0.0024) and PFS (p = 0.044). Factors predictive of local failure included lower BED (p = 0.016), treatment for recurrence (p = 0.029), and higher pre-treatment SUV (p = 0.026). Kaplan-Meier analysis showed BED ≤35 Gy (p < 0.005) and treatment for recurrence (p = 0.01) to be predictive of local failure. On Cox proportional hazards analysis, treatment of lymph nodes was predictive of complete radiographic response (hazard ratio (HR) = 4.95), as was higher BED (HR = 1.03). Toxicity included 27 cases of grade < 3 toxicity, and one grade 5 late toxicity of GI bleed from a radiation therapy-induced duodenal ulcer.

CONCLUSIONS

SBRT provides durable local control with minimal toxicity in ovarian cancer, especially with BED > 35 Gy and treatment for lymph nodes.

Stereotactic Body Radiotherapy for Oligometastatic Prostate Cancer Recurrence: A Meta-analysis

PURPOSE

The purpose of this study was to evaluate the treatment efficacy of stereotactic body radiotherapy (SBRT) in oligometastatic prostate cancer recurrence and to assess whether there is any relationship between biologically effective dose (BED) and local control (LC).

MATERIALS AND METHODS

Eligible studies were identified on Medline, Embase, and the Cochrane Library, and the proceedings of annual meetings through May 2019 were also identified. A meta-regression analysis was performed to assess whether there is a relationship between BED and LC. In the univariate analysis, studies were separated by the study design, the number of metastatic sites, the site of metastases, radiotherapy machine, and prostate-specific antigen level at the time of SBRT. A P-value <0.05 was considered significant.

RESULTS

Twenty-three observational studies with a total of 1441 lesions treated were included in the meta-analysis. The proportional rate of LC, progression-free survival, and androgen deprivation-free survival was 0.976 (95% confidence interval [CI]: 0.96-0.98), 0.413 (95% CI: 0.378-0.477), and 20.1 months (95% CI: 14.5-25.6), respectively. In the meta-regression, a linear relationship between BED and LC was detected (P=0.017). Stratifying the BED into 3 levels (BED<100 Gy3, BED 100 to 130 Gy3, and BED>130 Gy3), a significant difference was observed between BED<100 Gy3 (LC=88%) versus BED>100 Gy3 (LC=96%). The rate of any acute and late grade ≥2 toxicity was 1.3% and 1.2%, respectively.

CONCLUSIONS

The LC rate with SBRT was excellent with minimal severe acute/late toxicity. Our data suggest a dose relationship between BED and LC, with BED >100 Gy3 resulting in better rates of LC.

A phase III randomized-controlled, single-blind trial to improve quality of life with stereotactic body radiotherapy for patients with painful bone metastases (ROBOMET)

BACKGROUND

Bone metastases represent an important source of morbidity in cancer patients, mostly due to severe pain. Radiotherapy is an established symptomatic treatment for painful bone metastases, however, when conventional techniques are used, the effectiveness is moderate. Stereotactic body radiotherapy (SBRT), delivering very high doses in a limited number of fractions in a highly conformal manner, could potentially be more effective and less toxic.

METHODS

This is a phase III, randomized-controlled, single-blind, multicenter study evaluating the response rate of antalgic radiotherapy for painful bone metastases and the acute toxicity associated with this treatment. A total of 126 patients will be randomly assigned to receive either the standard schedule of a single fraction of 8.0 Gy delivered through three-dimensional conformal radiotherapy or a single fraction of 20.0 Gy delivered through SBRT. Primary endpoint is pain response at the treated site at 1 month after radiotherapy. Secondary endpoints are pain flare at 24-48-72 h after radiotherapy, duration of pain response, re-irradiation need, acute toxicity, late toxicity, quality of life and subsequent serious skeletal events. In a supplementary analysis, patient-compliance for a paper-and-pencil questionnaire will be compared with an electronic mode.

DISCUSSION

If a dose-escalated approach within the context of single fraction stereotactic body radiotherapy could improve the pain response to radiotherapy and minimize acute toxicity, this would have an immediate impact on the quality of life for a large number of patients with advanced cancer. Potential disadvantages of this technique include increased pain flare or a higher incidence of radiation-induced fractures.

TRIAL REGISTRATION

The Ethics committee of the GZA Hospitals (B099201732915) approved this study on September 4th 2018. Trial registered on Clinicaltrials.gov ( NCT03831243 ) on February 5th 2019.

Carbon 11-choline positron emission tomography/computed tomography and palliative local therapy for castration-resistant prostate cancer

PURPOSE

Carbon 11-choline positron emission tomography/computed tomography (11C-choline PET/CT) and subsequent local therapy for oligometastatic prostate cancer have been reported to be effective, but their effectiveness in castration-resistant prostate cancer (CRPC) remains unclear. Here, we evaluated the findings of 11C-choline PET/CT in CRPC patients and the efficacy of local treatments in correspondence of the pathologic choline uptake.

METHODS

We collected 12 cases of CRPC patients who underwent 11C-choline PET/CT between 2014 and 2016. The outcomes assessed included age, the prostate-specific antigen (PSA) value, the findings of 11C-choline PET/CT, the subsequent treatments, the PSA response following the treatments, and the progression-free survival (PFS).

RESULTS

Seven of 12 cases (median PSA, 3.29 ng/mL) had local prostate cancer and/or one or two metastatic lesions detected by the choline PET/CT. These localized lesions were treated with radiotherapy or lymphadenectomy. PSA decreased in all the seven cases and median PSA response was 86% (range, 23-100%). Median PFS was 8.5 months (range, 2.8-25.3 months). The other five cases (median PSA, 7.41 ng/mL) had multiple metastases and systemic therapies were continued in those cases.

CONCLUSIONS

11C-choline PET/CT and the correspondent local treatments may play an important role in the treatment sequence of CRPC in selected patients.

Local ablative stereotactic body radiotherapy for oligometastatic prostate cancer

PURPOSE OF REVIEW

The oligometastases is considered an intermediate state of the disease between localized and wide spread metastases. Local ablative therapy to oligometastatic prostate cancer is gaining significant traction and stereotactic body radiotherapy (SBRT) is an emerging treatment modality for this patient population. In this review, we report our literature review of SBRT to prostate oligometastases. Current evidence on the role of SBRT in oligometastatic prostate cancer reported in the last 10 years was summarized. Criteria for inclusion included studies with prostate cancer only as the primary site.

RECENT FINDINGS

The unique properties of the oligometastatic prostate cancer appear to carry a better prognosis than wide spread metastatic disease, especially if these metastases are amenable to local ablative therapies. Our literature review revealed that local ablative therapy, using SBRT to prostate oligometastases, is associated with significant 2-years local control and acceptable toxicity profile.

SUMMARY

SBRT to oligometastatic prostate cancer patients is feasible and carries an acceptable toxicity profile. The randomized phase II and III trials, currently underway, should clearly define the real benefit of this approach on progression-free and overall survival outcomes.

The role of radiotherapy in metastatic prostate cancer

The current standard of care for patients with metastatic prostate cancer includes ADT with a palliative intent. Recent studies have investigated the role of local therapy in metastatic prostate cancer. While retrospective data has shown some benefit with regard to survival and delay in initiation of ADT, there has been limited prospective Randomized data. To date, there has only been one recent randomized trial revealing a survival benefit with local radiotherapy, largely benefiting patients with the lowest burden of disease. The purpose of this review is to summarize the evidence and ongoing clinical trials regarding the role of radiotherapy in metastatic prostate cancer patients.

The Impact of 68Ga-PSMA PET/CT and PET/MRI on the Management of Prostate Cancer

Prostate-specific membrane antigen (PSMA) is a transmembrane protein with significantly increased expression in the cells and metastases of prostate carcinoma (CaP). PSMA-expression correlates with higher serum levels of prostate-specific antigen (PSA) and a higher Gleason score (GS). This finding has led to the development of novel imaging modalities such as 68Ga-/18F-labeled PSMA positron emission tomography/computed tomography (PET/CT) and positron emission tomography/magnetic resonance imaging (PET/MRI). This article reviews the literature pertaining to various new imaging technologies for the management of CaP. PSMA positron emission tomography/computed tomography appears to be an excellent diagnostic tool, that may drastically impact the management of a large number of patients with primary and recurrent CaP.

A Prospective Study on 18F-DCFPyL PSMA PET/CT Imaging in Biochemical Recurrence of Prostate Cancer

¹⁸F-DCFPyL (2-(3-{1-carboxy-5-[(6-¹⁸F-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid), a prostate-specific membrane antigen–targeting radiotracer, has shown promise as a prostate cancer imaging radiotracer. We evaluated the safety, sensitivity, and impact on patient management of ¹⁸F-DCFPyL in the setting of biochemical recurrence of prostate cancer. Methods: Subjects with prostate cancer and biochemical recurrence after radical prostatectomy or curative-intent radiotherapy were included in this prospective study. The subjects underwent ¹⁸F-DCFPyL PET/CT imaging. The localization and number of lesions were recorded. The uptake characteristics of the 5 most active lesions were measured. A pre- and posttest questionnaire was sent to treating physicians to assess the impact on management. Results: One hundred thirty subjects were evaluated. ¹⁸F-DCFPyL PET/CT localized recurrent prostate cancer in 60% of cases with a prostate-specific antigen (PSA) level of ≥0.4 to <0.5, 78% with a level of ≥0.5 to <1.0, 72% with a level of ≥1.0 to <2.0, and 92% with a level of ≥2.0. Many subjects had few lesions (1 lesion in 40.8%, 2 in 8.5%, and 3 in 4.6%). The number of lesions was significantly related to PSA by ANOVA, but there was a large overlap in the PSA values for number of lesion categories. Total lesion uptake was also significantly related to PSA level. A change in treatment intent occurred in 65.5% of subjects, disease stage changed in 65.5%, and management plans changed in 87.3%. Twenty-two subjects reported mild adverse events after the scan; all resolved completely. Conclusion:¹⁸F-DCFPyL PET/CT is safe and sensitive for the localization of biochemical recurrence of prostate cancer. This test improved decision making for referring oncologists and changed management for most subjects.

Performance and Impact of Prostate Specific Membrane Antigen-Based Diagnostics in the Management of Men with Biochemical Recurrence of Prostate Cancer and its Role in Salvage Lymph Node Dissection

Up to 50% of patients initially treated for prostate cancer in a curative intent experience biochemical recurrence, possibly requiring adjuvant treatment. However, salvage treatment decisions, such as lymph node dissection or radiation therapy, are typically based on prostate specific antigen (PSA) recurrence. Importantly, common imaging modalities (e.g., computed tomography [CT], magnetic resonance imaging, and bone scan) are limited and the detection of recurrent disease is particularly challenging if PSA is low. Prostate specific membrane antigen (PSMA) positron-emission tomography/computed tomography (PET/CT) is a novel and promising imaging modality which aims to overcome the incapability of early identification of distant and regional metastases. Within this review, we summarize the current evidence related to PSMA-PET/CT in prostate cancer men diagnosed with biochemical recurrence after local treatment with curative intent. We discuss detection rates of PSMA-PET/CT stratified by PSA-levels and its impact on clinical decision making. Furthermore, we compare different image-fusion techniques such as PSMA-PET vs. F-/C-Choline-PET scans vs. PSMA-single photon emission computed tomography/CT. Finally, we touch upon the contemporary role of radio-guided-PSMA salvage lymphadenectomy.

Oligometastases in prostate cancer: Ablative treatment

Technological advances in radiotherapy have led to the introduction of techniques such as stereotactic body radiation therapy (SBRT), allowing the administration of ablative doses. The hypothesis that oligometastatic disease may be cured through local eradication therapies has led to the increasing use of SBRT in patients with this type of disease. At the same time, scientific advances are being made to allow the confirmation of clinically suspected oligometastatic status at molecular level. There is growing interest in identifying patients with oligometastatic prostate cancer (PCa) who may benefit from curative intent metastasis-directed therapy, including SBRT. The aim is to complement, replace or delay the introduction of hormone therapy or other systemic therapies. The present review aims to compile the evidence from the main ongoing studies and results on SBRT in relation to oligometastatic PCa; examine aspects where gaps in knowledge or a lack of consensus persist (e.g., optimum schemes, response assessment, identification and diagnosis of oligometastatic patients); and document the lack of first-level evidence supporting the use of such techniques.

Single-fraction Stereotactic Body Radiation Therapy versus Conventionally Fractionated Radiation Therapy for the Treatment of Prostate Cancer Bone Metastases

Purpose

This study aimed to compare outcomes of patients with prostate cancer with bone metastases treated with stereotactic body radiation therapy (SBRT) versus conventionally fractionated radiation therapy (CFRT).

Methods and materials

An institutional, retrospective review was conducted of patients with prostate cancer receiving radiation therapy to bone metastases. In-field failure (IFF) was the primary outcome of the study, and distant failure (DF) and biochemical failure (BF) were secondary outcomes.

Results

A total of 249 metastases (191 SBRT; 58 CFRT) in 201 patients with a median follow-up of 2.2 years were analyzed. The SBRT prescription dose was predominantly 18 Gy (45.5%) or 20 Gy (46.6%) in a single fraction. CFRT was given either as 8 Gy in 1 fraction (56.9%) or 20 Gy in 5 fractions (41.4%). Imaging follow up was performed most frequently with ¹¹C-choline positron emission tomography/computed tomography (79%) or bone scan (10%). The median time to IFF was 1.6 years for CFRT-treated lesions and not met (>4.4 years) for SBRT. The 1- and 3-year IFF estimates were 34.4% (95% confidence interval [CI], 19.9-46.2) and 53.3% (95% CI, 34.3-66.8) for lesions treated with CFRT compared with 4.5% (95% CI, 1.4-7.5) and 12.9% (95% CI, 6.6-18-8) for those treated with SBRT (P < .01). On multivariate regression, the hazard ratio (HR) for IFF with CFRT compared with SBRT was 6.8 (95% CI, 3.7-12.5; P < .01). There were nonsignificant reduced rates of BF (HR, 1.4; 95% CI, 1.0-2.1; P = .05) and DF (HR, 1.3; 95% CI, 1.0-1.8; P = .08) in patients who received SBRT. The 3-year BF and DF estimates in these patients were 88.6% (95% CI, 82.0-92.8) and 82.2% (95% CI, 74.5-87.6), respectively.

Conclusions

SBRT for the management of prostate cancer bone metastases significantly reduces radiographic IFF. However, the high rate of subsequent DF and BF highlights the challenges in selecting patients who may benefit from aggressive radiation therapy.

Radiotherapy for oligometastatic cancer: a survey among radiation oncologists of Lombardy (AIRO-Lombardy), Italy

AIMS

To evaluate the use of radiotherapy (RT) for oligometastatic cancer (OMC) among radiation oncologists in Lombardy, Italy.

METHODS AND STUDY DESIGN

A survey with 12 items regarding data of 2016 was sent to all 34 Lombardy RT centers. The survey included six general items and six specific items regarding patient/disease/treatment characteristics.

RESULTS

Thirteen centers answered the survey (38%). All centers responded to general items and 12 centers submitted patient/disease/treatment data. General items The majority of centers (8/13) consider OMC if metastases number is less than 5. The most commonly prescribed dose/fraction is 5-10 Gy (8/13) using schedules of 3-5 fractions (11/13). Patient data items A total of 15.681 patients were treated in 2016 with external beam RT in 12 responding centers, and 1.087 patients were treated for OMC (7%). Primary tumor included lung, prostate, breast, colorectal and other malignancies in 33%, 21%, 12%, 9% and 25% of all OMC patients, respectively. Brain, lymph node, lung, bone, liver and others were the most common treated sites (24%, 24%, 22%, 17%, 8% and 5%, respectively). One and more than one metastasis were treated in 75 and 25% of patients, respectively. The vast majority of patients (95%) were treated with image-guided intensity-modulated RT or stereotactic RT.

CONCLUSIONS

Seven percent of all RT patients in Lombardy are treated for OMC. Extreme hypofractionation and high-precision RT are commonly employed. The initiative of multicenter and multidisciplinary collaboration has been undertaken in order to prepare the platform for prospective and/or observational studies in OMC.

Oligometastatic prostate cancer: Reality or figment of imagination?

The term “oligometastatic prostate cancer” refers to a heterogeneous group of disease states currently defined solely on the basis of clinical features. Oligorecurrent disease, de novo oligometastases, and oligoprogressive disease likely have unique biologic underpinnings and natural histories. Evidence suggesting the existence of a subset of patients who harbor prostate cancer with limited metastatic potential currently includes disparate and overwhelmingly retrospective reports. Nevertheless, emerging prospective data have corroborated the “better‐than‐expected,” retrospectively observed outcomes, particularly in the setting of oligorecurrent prostate cancer. Improved functional imaging with prostate‐specific membrane antigen‐targeted strategies may enhance the identification of patients with oligometastatic prostate cancer in the short term. In the long term, refinement of the oligometastatic case definition likely will require biologic risk‐stratification schemes. To determine optimal treatment strategies and identify patients most likely to benefit from metastasis‐directed therapy, future efforts should focus on conducting high‐quality, prospective trials with much‐needed molecular correlative studies.

The term “oligometastatic prostate cancer” currently refers to a heterogeneous group of clinically defined disease states. To improve patient risk stratification and determine optimal treatment strategies, future efforts should focus on conducting prospective trials and determining a biologic categorization of patients with limited metastatic potential.