Radiotherapy treatment volumes for oligorecurrent nodal prostate cancer: a systematic review

PEACE V-Salvage Treatment of OligoRecurrent nodal prostate cancer Metastases (STORM): Acute Toxicity of a Randomized Phase 2 Trial

BACKGROUND

Treatment recommendations for patients with limited nodal recurrences are lacking, and different locoregional treatment approaches are currently being used.

OBJECTIVE

The aim of this trial is to compare metastasis-directed therapy (MDT) with or without elective nodal pelvic radiotherapy (ENRT).

DESIGN, SETTING, AND PARTICIPANTS

PEACE V-Salvage Treatment of OligoRecurrent nodal prostate cancer Metastases (STORM) is an international, phase 2, open-label, randomized, superiority trial (ClinicalTrials.gov identifier: NCT03569241). Patients diagnosed with positron emission tomography-detected pelvic nodal oligorecurrence (five or fewer nodes) following radical local treatment for prostate cancer were randomized in a 1:1 ratio between arm A (MDT and 6 mo of androgen deprivation therapy [ADT]) and arm B (ENRT [25 × 1.8 Gy] with MDT and 6 mo of ADT).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We report the secondary endpoint acute toxicity, defined as worst grade ≥2 Common Terminology Criteria for Adverse Events v4.0 gastrointestinal (GI) or genitourinary (GU) toxicity within 3 mo of treatment. The chi-square test was used to compare toxicity between treatment arms. We also compare the quality of life (QoL) using the European Organisation for Research and Treatment of Cancer QLQ C30 and PR25 questionnaires.

RESULTS AND LIMITATIONS

Between June 2018 and April 2021, 196 patients were assigned randomly to MDT or ENRT. Ninety-seven of 99 patients allocated to MDT and 93 of 97 allocated to ENRT received per-protocol treatment. Worst acute GI toxicity proportions were as follows: grade ≥2 events in three (3%) in the MDT group versus four (4%) in the ENRT group (p = 0.11). Worst acute GU toxicity proportions were as follows: grade ≥2 events in eight (8%) in the MDT group versus 12 (13%) in the ENRT group (p = 0.95). We observed no significant difference between the study groups in the proportion of patients with a clinically significant QoL reduction from baseline for any subdomain score area.

CONCLUSIONS

No clinically meaningful differences were observed in worst grade ≥2 acute GI or GU toxicity or in QoL subdomains between MDT and ENRT.

PATIENT SUMMARY

We found no evidence of differential acute bowel or urinary side effects using metastasis-directed therapy and elective nodal radiotherapy for the treatment of patients with a pelvic lymph node recurrence.

Uncovering the armpit of SBRT: An institutional experience with stereotactic radiation of axillary metastases

Purpose/objectives

The growing use of stereotactic body radiotherapy (SBRT) in metastatic cancer has led to its use in varying anatomic locations. The objective of this study was to review our institutional SBRT experience for axillary metastases (AM), focusing on outcomes and process.

Materials/methods

Patients treated with SBRT to AM from 2014 to 2022 were reviewed. Cumulative incidence functions were used to estimate the incidence of local failure (LF), with death as competing risk. Kaplan-Meier method was used to estimate progression-free (PFS) and overall survival (OS). Univariate regression analysis examined predictors of LF.

Results

We analyzed 37 patients with 39 AM who received SBRT. Patients were predominantly female (60 %) and elderly (median age: 72). Median follow-up was 14.6 months. Common primary cancers included breast (43 %), skin (19 %), and lung (14 %). Treatment indication included oligoprogression (46 %), oligometastases (35 %) and symptomatic progression (19 %). A minority had prior overlapping radiation (18 %) or surgery (11 %). Most had prior systemic therapy (70 %).Significant heterogeneity in planning technique was identified; a minority of patient received 4-D CT scans (46 %), MR-simulation (21 %), or contrast (10 %). Median dose was 40 Gy (interquartile range (IQR): 35-40) in 5 fractions, (BED10 = 72 Gy). Seventeen cases (44 %) utilized a low-dose elective volume to cover remaining axilla.At first assessment, 87 % had partial or complete response, with a single progression. Of symptomatic patients (n = 14), 57 % had complete resolution and 21 % had improvement. One and 2-year LF rate were 16 % and 20 %, respectively. Univariable analysis showed increasing BED reduced risk of LF. Median OS was 21.0 months (95 % [Confidence Interval (CI)] 17.3-not reached) and median PFS was 7.0 months (95 % [CI] 4.3-11.3). Two grade 3 events were identified, and no grade 4/5.

Conclusion

Using SBRT for AM demonstrated low rates of toxicity and LF, and respectable symptom improvement. Variation in treatment delivery has prompted development of an institutional protocol to standardize technique and increase efficiency. Limited followup may limit detection of local failure and late toxicity.

Consensus Delineation Guidelines for Pelvic Lymph Node Radiation Therapy of Prostate Cancer: On Behalf of the Francophone Group of Urological Radiation Therapy (GFRU)

PURPOSE

Clinical target volume (CTV) delineation for pelvic lymph nodes in prostate cancer is currently based on 3 consensus guidelines with some inherent discrepancies. To improve the reproducibility in nodal delineation, the Francophone Group of Urological Radiotherapy (Groupe Francophone de Radiothérapie Urologique [GFRU]) worked toward proposing an easily applicable, reproducible, and practice-validated contouring guideline for pelvic nodal CTV.

METHODS AND MATERIALS

The nodal CTV data sets of a high-risk node-negative prostate cancer clinical case contoured by 86 radiation oncologists participating in a GFRU contouring workshop were analyzed. CTV volumes were defined before and after a structured presentation of literature data on lymphatic drainage pathways and patterns of nodal involvement and relapse, illustrated using a reference contour (CRef) defined by 3 GFRU experts. The consistency between the participants' contours and CRef was assessed quantitively by means of the Simultaneous Truth and Performance Level Estimation (STAPLE) method, the Dice coefficient, and the Hausdorff distance and qualitatively using a count map. These results combined with the literature review were thoroughly discussed among GFRU experts to reach a consensus.

RESULTS

From the 86 workshop participants, the volume of the STAPLE CTV was 591 cc compared with 502 cc for CRef. The Dice coefficient of the STAPLE CTV compared with the experts' CRef was 0.736 (±0.084) before and 0.823 (±0.070) after the workshop; the standard deviation decreased from 11.5% to 8.5% over the workshop. The Hausdorff distance of the STAPLE CTV compared with the CRef was 34.5 mm (±12.4) before the workshop and 21.8 mm (±9.3) after the workshop. Four areas of significant interobserver variability were identified, and a consensus was reached.

CONCLUSIONS

Using a robust methodology, our cooperative group proposed an easily applicable, reproducible, and practice-validated guideline for the delineation of the pelvic CTV in prostate cancer, useful for implementation in daily practice and clinical trials.

The diagnosis and treatment of castrate-sensitive oligometastatic prostate cancer: A review

BACKGROUND

Oligometastatic prostate cancer (OMPCa) is emerging as a transitional disease state between localized and polymetastatic disease. This review will assess the current knowledge of castrate-sensitive OMPCa.

METHODS

A review of the current literature was performed to summarize the definition and classification of OMPCa, assess the diagnostic methods and imaging modalities utilized, and to review the treatment options and outcomes. We further identify gaps in knowledge and areas for future research.

RESULTS

Currently there is no unified definition of OMPCa. National guidelines mostly recommend systemic therapies without distinguishing oligometastatic and polymetastatic disease. Next generation imaging is more sensitive than conventional imaging and has led to early detection of metastases at initial diagnosis or recurrence. While mostly retrospective in nature, recent studies suggest that treatment (surgical or radiation) of the primary tumor and/or metastatic sites might delay initiation of androgen deprivation therapy while increasing survival in selected patients.

CONCLUSIONS

Prospective data are required to better assess the incremental improvement in survival and quality of life achieved with various treatment strategies in patients with OMPCa.

Multi-institutional Development and Validation of Contouring Guidelines for Para-aortic Elective Nodal Irradiation in Prostate Cancer Based on Patterns of Involvement on Targeted Molecular Imaging Positron Emission Tomography/Computed Tomography

PURPOSE

Molecular imaging better identifies anatomic regions of metastatic spread of prostate cancer compared with conventional imaging, resulting in para-aortic (PA) nodal metastases being increasingly identified. Consequently, some radiation oncologists electively treat the PA lymph node region in patients with gross or high risk of PA nodal involvement. The anatomic locations of at-risk PA lymph nodes for prostate cancer are unknown. Our objective was to use molecular imaging to develop guidelines for the optimal delineation of the PA clinical target volume (CTV) in patients with prostate cancer.

METHODS AND MATERIALS

We conducted a multi-institutional retrospective cohort study of patients with prostate cancer undergoing 18F-fluciclovine or 18F-DCFPyL prostate-specific membrane antigen positron emission tomography (PET)/computed tomography (CT). Images of patients with PET-positive PA nodes were imported into the treatment planning system, avid nodes were contoured, and measurements were taken in relation to anatomic landmarks. A contouring guideline that encompassed the location of ≥95% of PET-positive PA nodes was created using descriptive statistics and then validated in an independent data set.

RESULTS

Five hundred fifty-nine patients had molecular PET/CT imaging in the development data set (78% 18F-fluciclovine, 22% prostate-specific membrane antigen). Seventy-six patients (14%) had evidence of PA nodal metastasis. We determined that expanding the CTV to 1.8 cm left of the aorta, 1.4 cm right of the inferior vena cava (IVC), 7 mm posterior to the aorta/IVC or to the vertebral body, and superiorly to the T11/T12 vertebral interface, with the anterior border 4 mm anterior to the aorta/IVC and inferior border at the bifurcation of the aorta/IVC, resulted in coverage of ≥95% of PET-positive PA nodes. When the guideline was used in the independent validation data set (246 patients with molecular PET/CT imaging, of whom 31 had PA nodal metastasis), 97% of nodes were encompassed, thereby validating our guideline.

CONCLUSIONS

We used molecular PET/CT imaging to determine the anatomic locations of PA metastases to develop contouring guidelines for creating a prostate cancer PA CTV. Although the optimal patient selection and clinical benefits of PA radiation therapy remain uncertain, our results will aid in delineating the optimal target when PA radiation therapy is pursued.

Elective Nodal Irradiation for Oligorecurrent Nodal Prostate Cancer: Interobserver Variability in the PEACE V-STORM Randomized Phase 2 Trial

Purpose

Consistency in delineation of pelvic lymph node regions for prostate cancer elective nodal radiation therapy is still challenging despite current guidelines. The aim of this study was to evaluate the interobserver variability in elective lymph node delineation in the PEACE V - STORM randomized phase 2 trial for oligorecurrent nodal prostate cancer.

Methods and Materials

Twenty-three centers were asked to delineate the elective pelvic nodal clinical target volume (CTV) of a postoperative oligorecurrent nodal prostate cancer benchmark case using a modified Radiation Therapy Oncology Group (RTOG) 2009 template (upper limit at the L4/L5 interspace). Overall, intersection and overflow volumes, Dice coefficient, Hausdorff distance, and count maps merged with computed tomography images were analyzed.

Results

The mean volume including the 23 nodal CTVs was 430.4 ± 64.1 cm3, larger than the modified RTOG 2009 CTV reference volume (386.1 cm3). The intersection common volume between the modified reference RTOG 2009 and the 23 nodal CTVs was estimated at 83.9%, whereas the overflow volume was 23.4%, mainly located at the level of the presacral and the upper limit of the L4/L5 interspace. The mean Dice coefficient was 0.79 ± 0.02, whereas the mean Hausdorff distance was 27 ± 4.4 mm.

Conclusions

In salvage radiation therapy treatment of oligorecurrent nodal prostate cancer, variations in elective lymph node volume delineation were mainly observed in the presacral and common iliac areas. Routine implementation and diffusion of available contouring guidelines together with a constant evaluation and evidence-based updating are expected to further decrease the existing variability in pelvic node contouring.

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.

Elective nodal radiotherapy with a gapless radiation field junction for oligorecurrent prostate cancer after previous radiotherapy

Purpose

To evaluate the feasibility of subsequent elective nodal radiotherapy (ENRT) for nodal recurrences after previous radiotherapy with a defined planning approach for a gapless radiation field junction.

Methods

Patients with 1) previous radiotherapy of prostate or prostatic fossa and subsequent pelvic ENRT or 2) previous pelvic radiotherapy and subsequent ENRT to paraaortic lymph nodes (LN) and gapless junction of both radiation fields were analyzed. The cumulative maximum dose (D_max-cum) and the maximum cumulative dose in 1 cc (D_1cc-cum) were estimated. Absolute toxicity and the toxicity exceeding baseline were evaluated.

Results

Twenty-two patients with PSMA-PET/CT-staged nodal oligorecurrence after prior radiotherapy were treated with pelvic (14 patients) or paraaortic ENRT (9 patients). One patient was treated sequentially at both locations. Median time between first and second RT was 20.2 months. Median doses to the lymphatic pathways and to PET-positive LN were 47.5 Gy and 64.8 Gy, respectively. The planning constraint of an estimated D_max-cum ≤ 95 Gy and of D_1cc-cum < 90 Gy were achieved in 23/23 cases and 22/23 cases, respectively. Median follow-up was 33.5 months. There was no additional acute or late toxicity ≥ grade 3. Worst acute toxicity exceeding baseline was grade 1 in 68.2% and grade 2 in 22.7% of patients. Worst late toxicity exceeding baseline was grade 1 in 31.8% and grade 2 in 18.2% of patients.

Conclusion

ENRT for nodal recurrences after a previous radiotherapy with gapless junction of radiation fields seems to be feasible, applying the dose constraints D_max-cum ≤ 95 Gy and D_1cc-cum < 90 Gy without grade 3 acute or late toxicities exceeding baseline.

Recommendations for radiation therapy in oligometastatic prostate cancer: An ESTRO-ACROP Delphi consensus

BACKGROUND AND PURPOSE

Oligometastatic prostate cancer is a new and emerging treatment field with only few prospective randomized studies published so far. Despite the lack of strong level I evidence, metastasis-directed therapies (MDT) are widely used in clinical practice, mainly based on retrospective and small phase 2 studies and with a large difference across centers. Pending results of ongoing prospective randomized trials, there is a clear need for more consistent treatment indications and radiotherapy practices.

MATERIAL AND METHODS

A European Society for Radiotherapy and Oncology (ESTRO) Guidelines Committee consisting of radiation oncologists' experts in prostate cancer was asked to answer a dedicated questionnaire, including 41 questions on the main controversial issues with regard to oligometastatic prostate cancer.

RESULTS

The panel achieved consensus on patient selection and routine use of prostate-specific membrane antigen positron emission tomography (PSMA PET) imaging as preferred staging and restaging imaging. MDT strategies are recommended in the de novo oligometastatic, oligorecurrent and oligoprogressive disease setting for nodal, bone and visceral metastases. Radiation therapy doses, volumes and techniques were discussed and commented.

CONCLUSION

These recommendations have the purpose of providing standardization and consensus to optimize the radiotherapy treatment of oligometastatic prostate cancer until mature results of randomized trials are available.

Oligorecurrent nodal prostate cancer: radiotherapy quality assurance of the randomized PEACE V-STORM phase II trial

PURPOSE

Aim of this study is to report the results of the radiotherapy quality assurance program of the PEACE V-STORM randomized phase II trial for pelvic nodal oligorecurrent prostate cancer (PCa).

MATERIAL AND METHODS

A benchmark case (BC) consisting of a postoperative case with 2 nodal recurrences was used for both stereotactic body radiotherapy (SBRT, 30 Gy/3 fx) and whole pelvic radiotherapy (WPRT, 45 Gy/25 fx + SIB boost to 65 Gy).

RESULTS

BC of 24 centers were analyzed. The overall grading for delineation variation of the 1st BC was rated as 'UV' (Unacceptable Variation) or 'AV' (Acceptable Variation) for 1 and 7 centers for SBRT (33%), and 3 and 8 centers for WPRT (46%), respectively. An inadequate upper limit of the WPRT CTV (n=2), a missing delineation of the prostate bed (n=1), and a missing nodal target volume (n=1 for SBRT and WPRT) constituted the observed 'UV'. With the 2nd BC (n=11), the overall delineation review showed 2 and 8 'AV' for SBRT and WPRT, respectively, with no 'UV'. For the plan review of the 2nd BC, all treatment plans were per protocol for WPRT. SBRT plans showed variability in dose normalization (Median D_90% = 30.1 Gy, range 22.9-33.2Gy and 30.6 Gy, range 26.8-34.2Gy for nodes 1 and 2 respectively).

CONCLUSIONS

Up to 46% of protocol deviations were observed in delineation of WPRT for nodal oligorecurrent PCa, while dosimetric results of SBRT showed the greatest disparities between centers. Repeated BC resulted in an improved adherence to the protocol, translating in an overall acceptable contouring and planning compliance rate among participating centers.

Local Control after Locally Ablative, Image-Guided Radiotherapy of Oligometastases Identified by Gallium-68-PSMA-Positron Emission Tomography in Castration-Sensitive Prostate Cancer Patients (OLI-P)

Simple Summary

In this clinical trial, 63 patients with a total of 89 prostate cancer metastases identified on PSMA-PET were included, none of them undergoing androgen deprivation therapy. We showed that local ablative radiotherapy controls >90% of the metastases, but progression at other sites is common after two years. Local ablative radiotherapy may be an option to at least temporarily avoid systemic therapy in selected patients.

Abstract

Progression of prostate-specific antigen (PSA) values after curative treatment of prostate cancer patients is common. Prostate-specific membrane antigen (PSMA-) PET imaging can identify patients with metachronous oligometastatic disease even at low PSA levels. Metastases-directed local ablative radiotherapy (aRT) has been shown to be a safe treatment option. In this prospective clinical trial, we evaluated local control and the pattern of tumor progression. Between 2014 and 2018, 63 patients received aRT of 89 metastases (MET) (68 lymph node (LN-)MET and 21 bony (OSS-)MET) with one of two radiation treatment schedules: 50 Gy in 2 Gy fractions in 34 MET or 30 Gy in 10 Gy fractions in 55 MET. The mean gross tumor volume and planning target volume were 2.2 and 14.9 mL, respectively. The median follow-up time was 40.7 months. Local progression occurred in seven MET, resulting in a local control rate of 93.5% after three years. Neither treatment schedule, target volume, nor type of lesion was associated with local progression. Regional progression in the proximity to the LN-MET was observed in 19 of 47 patients with at least one LN-MET (actuarial 59.3% free of regional progression after 3 years). In 33 patients (52%), a distant progression was reported. The median time to first tumor-related clinical event was 16.6 months, and 22.2% of patients had no tumor-related clinical event after three years. A total of 14 patients (22%) had another aRT. In conclusion, local ablative radiotherapy in patients with PSMA-PET staged oligometastatic prostate cancer may achieve local control, but regional or distant progression is common. Further studies are warranted, e.g., to define the optimal target volume coverage in LN-MET and OSS-MET.

Prognostic factors, efficacy, and toxicity of involved-node stereotactic body radiation therapy for lymph node oligorecurrent prostate cancer : An investigation of 117 pelvic lymph nodes

BACKGROUND

The optimal radiotherapy regimen is not yet defined in the setting of oligorecurrent prostate cancer (oligorPC). There is evidence of high variability in treatment protocols among different centers worldwide, and no international consensus guidelines on treatment volumes, radiation schedules, and techniques. The purpose of the present retrospective study is to evaluate the efficacy and safety of involved-pelvic-node stereotactic body radiotherapy (SBRT) for oligorPC.

MATERIALS AND METHODS

Patients with pelvic node oligorPC following primary surgery, radical radiotherapy, or salvage radiotherapy for biochemical or local relapse of prostate cancer who underwent involved-node SBRT with biological effective dose (BED) > 100 Gy, with or without concurrent and adjuvant androgen deprivation therapy (ADT), were retrospectively evaluated. Biochemical progression-free survival (bPFS), distant progression-free survival (DPFS), overall survival (OS), possible prognostic factors, and toxicity outcomes were investigated.

RESULTS

From November 2012 to December 2019, 74 patients fitted the selection criteria. A total of 117 lesions were treated. Median follow-up was 31 months (range 6-89). Concurrent ADT was administered in 58.1% of patients. The 1‑year, 2‑year, and 3‑year DPFS was 77%, 37%, and 19%, respectively; the 1‑year, 2‑year, and 3‑year OS was 98%, 98%, and 95%, respectively. The presence of a single target lesion was associated with a statistically significant impact on OS. No in-field recurrence occurred. Patients who reached early prostate-specific antigen (PSA) nadir (< 3 months after SBRT) had a lower 3‑year survival (p = 0.004). The value of PSA nadir after SBRT and the time between primary treatment and SBRT had an impact on bPFS. Concomitant ADT was associated with improved DPFS. No acute or early late (> 6 months) genitourinary and gastrointestinal adverse events of any grade were reported, albeit with relatively short median follow-up.

CONCLUSION

SBRT is a safe and effective treatment for oligorPC, with a 100% local control rate in our series. It is not possible to clearly assess the opportunity to postpone ADT prescription in patients with two or more nodal metastases. The number of secondary lesions, time-to-nadir PSA, PSA nadir value, and the time interval between primary treatment and SBRT were identified as prognostic factors. Future prospective randomized studies are desirable to better understand the still open questions regarding the oligorecurrent prostate cancer state.

Outcome after PSMA-PET/CT-based salvage radiotherapy for nodal recurrence after radical prostatectomy

Purpose

Nodal recurrent prostate cancer (PCa) represents a common state of disease, amenable to local therapy. PSMA-PET/CT detects PCa recurrence at low PSA levels. The aim of this study was to evaluate the outcome of PSMA-PET/CT-based salvage radiotherapy (sRT) for lymph node (LN) recurrence.

Methods

A total of 100 consecutive patients treated with PSMA-PET/CT-based salvage elective nodal radiotherapy (sENRT) for LN recurrence were retrospectively examined. Patients underwent PSMA-PET/CT scan due to biochemical persistence (bcP, 76%) or biochemical recurrence (bcR, 24%) after radical prostatectomy (RP). Biochemical recurrence-free survival (BRFS) defined as PSA < post-RT nadir + 0.2 ng/ml and distant metastasis-free survival (DMFS) were calculated using the Kaplan–Meier method and uni- and multivariate analysis was performed.

Results

Median follow-up was 37 months. Median PSA at PSMA-PET/CT was 1.7 ng/ml (range 0.1–40.1) in patients with bcP and 1.4 ng/ml (range 0.3–5.1) in patients with bcR. PSMA-PET/CT detected 1, 2, and 3 or more LN metastases in 35%, 23%, and 42%, respectively. Eighty-three percent had only pelvic, 2% had only paraaortic, and 15% had pelvic and paraaortic LN metastases. Cumulatively, a total dose converted to EQD2_1.5 Gy of 66 Gy (60–70 Gy) was delivered to the prostatic fossa, 70 Gy (66–72 Gy) to the local recurrence, if present, 65.1 Gy (56–66 Gy) to PET-positive lymph nodes, and 47.5 Gy (42.4–50.9 Gy) to the lymphatic pathways. Concomitant androgen deprivation therapy (ADT) was administered in 83% of patients. One-, 2-, and 3-year BRFS was 80.7%, 71.6%, and 65.8%, respectively. One-, 2-, and 3-year DMFS was 91.6%, 79.1%, and 66.4%, respectively. In multivariate analysis, concomitant ADT, longer ADT duration (≥ 12 vs. < 12 months) and LN localization (pelvic vs. paraaortic) were associated with improved BRFS and concomitant ADT and lower PSA value before sRT (< 1 vs. > 1 ng/ml) with improved DMFS, respectively. No such association was seen for the number of affected lymph nodes.

Conclusions

Overall, the present analysis shows that the so far, unmatched sensitivity and specificity of PSMA-PET/CT translates in comparably high BRFS and DMFS after PSMA-PET/CT-based sENRT for patients with PCa LN recurrence. Concomitant ADT, duration of ADT, PSA value before sRT, and localization of LN metastases were significant factors for improved outcome.

PET/CT-Based Salvage Radiotherapy for Recurrent Prostate Cancer After Radical Prostatectomy: Impact on Treatment Management and Future Directions

Biochemical recurrence is a clinical situation experienced by 20 to 40% of prostate cancer patients treated with radical prostatectomy (RP). Prostate bed (PB) radiation therapy (RT) remains the mainstay salvage treatment, although it remains non-curative for up to 30% of patients developing further recurrence. Positron emission tomography with computed tomography (PET/CT) using prostate cancer-targeting radiotracers has emerged in the last decade as a new-generation imaging technique characterized by a better restaging accuracy compared to conventional imaging. By adapting targeting of recurrence sites and modulating treatment management, implementation in clinical practice of restaging PET/CT is challenging the established therapeutic standards born from randomized controlled trials. This article reviews the potential impact of restaging PET/CT on changes in the management of recurrent prostate cancer after RP. Based on PET/CT findings, it addresses potential adaptation of RT target volumes and doses, as well as use of androgen-deprivation therapy (ADT). However, the impact of such management changes on the oncological outcomes of PET/CT-based salvage RT strategies is as yet unknown.

Elective nodal radiotherapy in prostate cancer

In patients with prostate cancer who have a high risk of pelvic nodal disease, the use of elective whole pelvis radiotherapy is still controversial. Two large, randomised, controlled trials (RTOG 9413 and GETUG-01) did not show a benefit of elective whole pelvis radiotherapy over prostate-only radiotherapy. In 2020, the POP-RT trial established the role of elective whole pelvis radiotherapy in patients who have more than a 35% risk of lymph node invasion (known as the Roach formula). POP-RT stressed the importance of patient selection. In patients with cN1 (clinically node positive) disease or pN1 (pathologically node positive) disease, the addition of whole pelvis radiotherapy to androgen deprivation therapy significantly improved survival compared with androgen deprivation therapy alone, as shown in large, retrospective studies. This patient population might increase in the future because use of the more sensitive prostate-specific membrane antigen PET-CT will become the standard staging procedure. Additionally, the SPORTT trial suggested a benefit of whole pelvis radiotherapy in biochemical recurrence-free survival in the salvage setting. A correct definition of the upper field border, which should include the bifurcation of the abdominal aorta, is key in the use of pelvic radiotherapy. As a result of using modern radiotherapy technology, severe late urinary and intestinal toxic effects are rare and do not seem to increase compared with prostate-only radiotherapy.

Oligorecurrent Prostate Cancer and Stereotactic Body Radiotherapy: Where Are We Now? A Systematic Review and Meta-analysis of Prospective Studies

CONTEXT

The optimal management of oligometastatic prostate cancer (PCa) is still debated.

OBJECTIVE

The purpose of the present systematic review and meta-analysis is to collect the available evidence to date to better define the role of stereotactic body radiotherapy (SBRT) in selected patients with oligorecurrent PCa.

EVIDENCE ACQUISITION

Study methodology complied with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). All prospective studies including PCa patients with nodal and/or bone oligometastases (one to five lesions) were considered eligible. Heterogeneity between study-specific estimates was tested using chi-square statistics and measured with the I2 index. A pooled estimate was obtained by fitting both fixed-effect and DerSimonian and Laird random-effect model.

EVIDENCE SYNTHESIS

Overall, six works (two randomized and the remainder observational) published between 2013 and 2020 were considered eligible. Globally, data from 445 patients were incorporated, of whom 396 were treated with SBRT (329 in observational studies and the remaining 67 in randomized ones). Regarding local progression-free survival (PFS), five studies reported values close to 100%, while one reported a value of 80% in the observation arm. The benefit in terms of biochemical PFS brought by SBRT was evident in all considered studies. Such a difference in cumulative probabilities between the intervention arm and the comparator arm is maintained even 24 mo after the baseline. All studies but one considered toxicity among the endpoints of interest. Most events were classified as either G1 or G2, and the only G ≥ 3 adverse event was reported in one trial.

CONCLUSIONS

SBRT is highly cost effective, safe, and with an almost inexistent toxicity risk that makes it the perfect candidate for the optimal management of PCa oligometastatic patients. However, more solid data and a higher level of evidence are needed to affirm its role in the management of these patients.

PATIENT SUMMARY

In this work, we reviewed available evidence on the use of stereotactic body radiotherapy in treating oligometastatic prostate cancer patients. We found good evidence that radiotherapy brings important benefits in overall treatment efficacy without major side effects.

Prostate-specific membrane antigen targeted PET/CT for recurrent prostate cancer: a clinician's guide

INTRODUCTION

PSMA-targeted PET/CT is a 'Next Generation Imaging' technique with superior sensitivity and specificity for detecting recurrent prostate cancer compared with conventional imaging, allowing more accurate staging and re-staging.

AREAS COVERED

This article reviews the role of PSMA-targeted PET/CT in clinical management of men with recurrent prostate cancer.

EXPERT OPINION

Through enhanced spatial characterization of recurrent prostate cancer, PSMA-targeted PET/CT has shown significant impact on management decisions. In particular, by identifying men with recurrence confined to the prostate or pelvic nodes, PSMA-targeted PET/CT enables selective deployment of localized salvage therapies for management of biochemical failure after primary treatment with prostatectomy or radiotherapy. In oligometastatic disease, PSMA-targeted PET/CT may improve patient selection and treatment accuracy for metastasis-directed therapy and early phase II studies show encouraging results in delaying the need for systemic therapy. Further, quantitative PSMA-targeted PET/CT for monitoring response and therapeutic PSMA-targeted radiopharmaceuticals are emerging as encouraging treatment options in the setting of castrate-resistant disease.

M1a prostate cancer: Results of a Dutch multidisciplinary consensus meeting

Objectives

To determine the consensus of a Dutch multidisciplinary expert panel on the diagnostic evaluation and treatment of de novo and recurrent metastatic prostate cancer (PCa) limited to non‐regional lymph nodes (M1a) in daily clinical practice.

Materials and methods

The panel consisted of 37 Dutch specialists from disciplines involved in the management of M1a PCa (urology, medical and radiation oncology, radiology, and nuclear medicine). We used a modified Delphi method consisting of two voting rounds and a consensus meeting (video conference). Consensus (good agreement) was defined as the situation in which ≥ 75% of the panelists chose the same option.

Results

Consensus existed for 57% of the items. The panel agreed that prostate‐specific membrane antigen positron emission tomography/computed tomography (PSMA‐PET/CT) is the most appropriate standard imaging modality to identify de novo (100%) and recurrent (97%) M1a PCa. Androgen deprivation therapy (ADT) combined with radiotherapy to the prostate ± the M1a lesion(s) was most frequently considered an option for de novo M1a PCa. For M1a as recurrent disease, ADT alone, deferring treatment, or local radiotherapy to the M1a lesion(s) were judged to be the most important treatment options. However, no specific indications for treatment choice in relation to disease characteristics could be formulated.

Conclusions

The Dutch consensus panel preferred PSMA‐PET/CT as the standard diagnostic modality to detect M1a PCa. Although potential treatment options were identified, explicit recommendations could not be formulated. This might (partly) be explained by the absence of high‐level clinical evidence in this subset of patients. Further research is, therefore, strongly encouraged.

Rationale for Involved Field Stereotactic Body Radiation Therapy-Enhanced Intermittent Androgen Deprivation Therapy in Hormone-Sensitive Nodal Oligo-Recurrent Prostate Cancer Following Prostate Stereotactic Body Radiation Therapy

Lymph node recurrent prostate cancer is a common clinical scenario that is likely to increase significantly with the widespread adoption of novel positron emission tomography (PET) agents. Despite increasing evidence that localized therapy is disease modifying, most men with lymph node recurrent prostate cancer receive only systemic therapy with androgen deprivation therapy (ADT). For men who receive localized therapy the intent is often to delay receipt of systemic therapy. Little evidence exists on the optimal combination of local and systemic therapy in this patient population. In this hypothesis generating review, we will outline the rationale and propose a framework for combining involved field SBRT with risk adapted intermittent ADT for hormone sensitive nodal recurrent prostate cancer. In patients with a limited number of nodal metastases, involved field stereotactic body radiation therapy (SBRT) may have a role in eliminating castrate-resistant clones and possibly prolonging the response to intermittent ADT. We hypothesize that in a small percentage of patients, such a treatment approach may lead to long term remission or cure.

The Distribution of Pelvic Nodal Metastases in Prostate Cancer Reveals Potential to Advance and Personalize Pelvic Radiotherapy

Background

Traditional clinical target volume (CTV) definition for pelvic radiotherapy in prostate cancer consists of large volumes being treated with homogeneous doses without fully utilizing information on the probability of microscopic involvement to guide target volume design and prescription dose distribution.

Methods

We analyzed patterns of nodal involvement in 75 patients that received RT for pelvic and paraaortic lymph node metastases (LNs) from prostate cancer in regard to the new NRG-CTV recommendation. Non-rigid registration-based LN mapping and weighted three-dimensional kernel density estimation were used to visualize the average probability distribution for nodal metastases. As independent approach, the mean relative proportion of LNs observed for each level was determined manually and NRG and non-NRG levels were evaluated for frequency of involvement. Computer-automated distance measurements were used to compare LN distances in individual patients to the spatial proximity of nodal metastases at a cohort level.

Results

34.7% of patients had pelvic LNs outside NRG-consensus, of which perirectal was most common (25.3% of all patients) followed by left common iliac nodes near the left psoas major (6.7%). A substantial portion of patients (13.3%) had nodes at the posterior edge of the NRG obturator level. Observer-independent mapping consistently visualized high-probability hotspots outside NRG-consensus in the perirectal and left common iliac regions. Affected nodes in individual patients occurred in highly significantly closer proximity than at cohort-level (mean distance, 6.6 cm vs. 8.7 cm, p < 0.001).

Conclusions

Based on this analysis, the common iliac level should extend to the left psoas major and obturator levels should extend posteriorly 5 mm beyond the obturator internus. Incomplete coverage by the NRG-consensus was mostly because of perirectal involvement. We introduce three-dimensional kernel density estimation after non-rigid registration-based mapping for the analysis of recurrence data in radiotherapy. This technique provides an estimate of the underlying probability distribution of nodal involvement and may help in addressing institution- or subgroup-specific differences. Nodal metastases in individual patients occurred in highly significantly closer proximity than at a cohort-level, which supports that personalized target volumes could be reduced in size compared to a “one-size-fits-all” approach and is an important basis for further investigation into individualized field designs.

The Multicenter, Randomized, Phase 2 PEACE V-STORM Trial: Defining the Best Salvage Treatment for Oligorecurrent Nodal Prostate Cancer Metastases

Optimal local treatment for nodal oligorecurrent prostate cancer is unknown. The randomized phase 2 PEACE V-STORM trial will explore the best treatment approach in this setting. Early results on the acute toxicity profile are projected to be published in quarter 3, 2021.

Functional Implication of Exosomal miR-217 and miR-23b-3p in the Progression of Prostate Cancer

Objective

The microRNA expression profile of plasma exosomes in prostate cancer (PCa) is of critical importance in the disease exploration. This study aimed to explore the clinical application of exosomal miRNAs as biomarkers for PCa.

Methods

Exosome-like vesicles of PCa patients and healthy controls were purified by differential centrifugation. The purified vesicles within the ranges of 50 and 100 nm were classified as exosomes according to the results of transmission electron microscopy and Western blot. Both, in vitro and in vivo, validations were performed by small RNA sequencing, CCK8, RT-qPCR, flow cytometry, Western blot, transwell and immunofluorescent staining assays.

Results

High-throughput sequencing identified that 94 miRNAs were differentially expressed in PCa patients in comparison with healthy controls (P<0.01; fold change ≥2). Among them, 64 miRNAs were upregulated, and 30 miRNAs were downregulated. In comparison to the healthy controls, the expression levels of miR-217 were significantly upregulated, while miR-23b-3p were significantly downregulated in the exosomes and serum collected from PCa patients. Both, in vitro and in vivo, studies revealed that exosomes secreted by PCa cells with up-regulated miR-217 levels promoted cell proliferation and invasion; meanwhile, the exosomes with up-regulated miR-23b-3p levels inhibited cell proliferation and invasion. The epithelial–mesenchymal transition process may have been involved in the above-mentioned regulation.

Conclusion

This study identified the dysregulated expression of exosomal miRNAs in PCa patients, including miR-217 and miR-23b-3p, by validating their function on proliferation and invasion in PCa cells. This regulation may have been affected by the epithelial–mesenchymal transition process, suggesting that they can be used as potential targets in the diagnosis and treatment of PCa.