Clinical Outcomes of Combined Prostate- and Metastasis-Directed Radiation Therapy for the Treatment of De Novo Oligometastatic Prostate Cancer

The Role of Local Prostate and Metastasis-Directed Radiotherapy in the Treatment of Oligometastatic Prostate Cancer

Background/Objectives: Oligometastatic prostate cancer (OMPC) represents an early stage of metastatic disease characterized by a limited number of lesions. Recent advancements in imaging and treatment have revived interest in personalized therapies, including metastasis-directed radiotherapy (OMDRT) and primary prostate radiotherapy (PPR). This study evaluates the impact of OMDRT timing and the role of PPR on survival outcomes in OMPC patients; Methods: In this retrospective cohort study, 82 patients with OMPC who underwent OMDRT between 2010 and 2019 were analyzed. Patients were classified based on OMDRT timing (early vs. late) and disease type (synchronous vs. metachronous). Progression-free survival (PFS) and overall survival (OS) were the primary endpoints, assessed via Kaplan-Meier analysis and Cox proportional hazards models; Results: Among the patients, 36 (43.9%) had synchronous and 46 (56.1%) had metachronous OMD. With a median follow-up of 32 months, the 5-year PFS and OS rates were 77.5% and 88.5%, respectively. Early OMDRT significantly improved PFS (HR 0.461, 95% CI: 0.257-0.826, p = 0.009) and OS (HR 0.219, 95% CI: 0.080-0.603, p = 0.003). Subgroup analysis showed the most favorable outcomes for synchronous OMD patients receiving early OMDRT, with a median PFS of 22.2 months and a 5-year survival rate of 42.1%. The treatment of the primary prostate provided a survival benefit in the OS of synchronous OMD patients (5-year 83.1% vs. 50%, p = 0.025), and there was a further improvement in OS after PPR (5-year 87.7% vs. 50%, p = 0.015). Conclusions: Early OMDRT significantly enhances survival outcomes in OMPC, in both synchronous and metachronous cases. The integration of PPR can further improve results, emphasizing the importance of early intervention and personalized treatment strategies. To more definitively clarify our findings across various clinical situations, further studies with larger cohorts or prospective designs are necessary.

A Phase II Trial of Stereotactic Body Radiation Therapy and Androgen Deprivation for Oligometastases in Prostate Cancer (SBRT-SG 05)

PURPOSE

SBRT-Spanish Group-05 (ClinicalTrials.gov.Identifier: NCT02192788) is a collaborative (SBRT-SG, Grupo de Investigación Clínica en Oncología Radioterápica, and Sociedad Española de Oncología Radioterápica) prospective multicenter phase II trial testing stereotactic body radiation therapy (SBRT) and androgen deprivation therapy (ADT) in patients with oligorecurrent prostate cancer.

METHODS AND MATERIALS

Two cohorts of patients with prostate cancer in an oligorecurrent stage (hormone-sensitive in the principal cohort and castration-resistant in the exploratory cohort) were assigned to receive ADT and SBRT for at least 24 months from the time of the enrollment. Concomitant treatment with chemotherapy, abiraterone, or enzalutamide was not allowed. Oncologic outcomes were assessed in both cohorts. Toxicity was prospectively analyzed.

RESULTS

From 2014 to 2019, 81 patients with a total of 126 lesions from 14 centers met the inclusion criteria, 14 of whom were castration-resistant. With a median follow-up of 40 months (12-58 months), 3-year local recurrence-free survival was 92.5% (95% CI, 79.9%-96.3%) and 85.7% (95% CI, 48.2%-95.6%) in the principal and exploratory cohorts, respectively. In the principal cohort, biochemical relapse-free survival and metastasis progression-free survival at 1, 2, and 3 years were 91% (95% CI, 81%-95.8%), 73.7% (95% CI, 61.1%-82.8%), 50.6% (95% CI, 36.2%-63.3%), and 92% (95% CI, 83%-97%), 81% (95% CI, 70%-89%), and 67% (95% CI, 53%-77%), respectively. In the exploratory cohort, metastasis progression-free survival at 1, 2, and 3 years was 64% (95% CI, 34%-83%), 43% (95% CI, 18%-66%), and 26% (95% CI, 7%-51%), respectively. None of the patients developed grade III or higher toxicity or symptoms related to local progression, and only 2 (2.4%) patients developed grade II toxicity.

CONCLUSIONS

The combination of SBRT and ADT is safe and shows favorable clinical outcomes in patients with hormone-sensitive and castration-resistant prostate cancer. Validation studies are needed in patients with castration-resistant prostate cancer.

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.

Protocol for Evaluating the Efficacy and Safety of Radiotherapy for Prostate and Oligometastatic Lesions in Patients With Low-Burden Sensitive Oligometastatic Prostate Cancer: An Open, Exploratory Pilot Clinical Trial

INTRODUCTION

The existing large prospective study demonstrates the benefits of primary radiotherapy in patients with low-volume oligometastatic prostate cancer (OMPC), and there is additional evidence of the benefits of local metastasis-directed therapy (MDT) for metastatic lesions. However, there are no results from a prospective study to demonstrate the efficacy of radiotherapy for prostate and oligometastases. Therefore, the aim of the protocol is to illustrate the efficacy of radiotherapy for prostate and oligometastatic lesions in patients with low-volume de novo hormone-sensitive OMPC.

METHODS AND ANALYSIS

This study involves a prospective, single-center, limited-sample, single-arm exploration of radiotherapy for prostate and oligometastatic lesions in patients diagnosed with low-volume hormone-sensitive OMPC. Eligible participants undergo thorough assessments and treatment involving endocrine therapy alongside radiation targeting metastatic lesions and the pelvic region. The primary site is treated with volumetric modulated arc therapy (VMAT), while metastatic sites are treated with either VMAT or stereotactic body radiation therapy (SBRT) depending on their location. All patients received radiation therapy for both the primary and metastatic lesions combined with endocrine therapy. Endocrine therapy with an antiandrogen (bicalutamide, for 4 weeks) androgen deprivation therapy combined with novel hormonal agents (acetate abiraterone) will be continued for 2 years. The primary objective is to evaluate progression-free survival-2 (PFS-2), while secondary endpoints include androgen deprivation therapy (ADT)-free survival, quality of life (QoL), overall survival, time to castration-resistant prostate cancer (CRPC), radiation-related complications, and endocrine therapy-related adverse events.

ETHICS AND DISSEMINATION

Approval was obtained from the ethics committee of the First Affiliated Hospital of Naval Medical University (CHEC2023-220). This is a single-arm exploration pilot trial evaluating radiotherapy for prostate and oligometastatic lesions in patients with OMPC. It aims to disseminate its findings through peer-reviewed journals and relevant medical conferences, with the intention of publication and presentation at these events.

TRIAL REGISTRATION NUMBERS

Clinicaltrials.gov identifier NCT06198387.

Real-world evidence of outcomes of oligometastatic hormone-sensitive prostate cancer patients treated with metastasis-directed therapy

OBJECTIVE

To investigate characteristics and outcomes of oligometastatic hormone-sensitive prostate cancer (mHSPC) patients undergoing metastases-directed therapy (MDT) with external beam radiation therapy (EBRT).

MATERIALS AND METHODS

We relied on an institutional tertiary-care database to identify mHSPC patients who underwent EBRT as MDT between 12/2019 and 12/2022. Main outcomes consisted of progression to metastatic castration-resistant prostate cancer (mCRPC) and overall mortality (OM). Oligometastatic was defined as ≤3 metastases and bone and/or lymph node deposits were treated with conventional doses up to 54 Gy or with hypofractionated stereotactic regimes of median 24 Gy (20-27 Gy).

RESULTS

Overall, 37 patients treated with EBRT as MDT were identified. The median follow-up was 13 months. Median age at MDT was 71 years and 84% exhibited ECOG performance status 0. The median baseline PSA at diagnosis was 10 ng/mL. Overall, primary local therapy consisted of radical prostatectomy (65%), followed by external beam radiation therapy to the prostate (11%), focal therapy (8%), and palliative transurethral resection of the prostate (5%). Overall, 32% exhibited de novo oligometastatic mHSPC. Bone metastases were present in 78% versus 19% lymph node metastases versus 3% both. The distribution of targeted oligo-metastases was 62% versus 38% for respectively one metastasis versus more than one metastasis. Androgen deprivation therapy (ADT) was combined with MDT in 84%. Moreover, 19% received combination therapy with apalutamide/enzalutamide and 12% with abiraterone or docetaxel. The median time to mCRPC was 50 months. In incidence analyses, 13% developed mCRPC after 24 months. OM after 24 months was 15% in mHSPC patients receiving MDT. Significant OM differences were observed after stratification into targeted metastatic burden (<0.05). No high-grade adverse events were recorded during MDT.

CONCLUSION

Our real-world data suggest that MDT represents a safe treatment option for well-selected oligometastatic mHSPC patients.

Oncological and perioperative outcomes of surgery with or without metastasis-directed therapy as part of a multimodal treatment in men with de-novo oligometastatic prostate cancer

PURPOSE

To investigate the feasibility, safety, and oncological outcomes of Radical Prostatectomy (RP; either Robot-Assisted [RARP] or Open RP [ORP]) in oligometastatic prostate cancer (omPCa). Additionally, we assessed whether there was an added benefit of metastasis-directed therapy (MDT) in these patients in the adjuvant setting.

METHODS

Overall, 68 patients with omPCa (≤ 5 skeletal lesions at conventional imaging) treated with RP and pelvic lymph node dissection between 2006 and 2022 were included. Additional therapies (androgen deprivation therapy [ADT] and MDT) were administered according to the treating physicians' judgment. MDT was defined as metastasis surgery/radiotherapy within 6 months of RP. We assessed Clinical Progression (CP), Biochemical Recurrence (BCR), post-operative complications and overall mortality (OM) of RP and the impact of adjuvant MDT + ADT versus RP + ADT alone.

RESULTS

Median follow-up was 73 months (IQR 62-89). RARP reduced the risk of severe complications after adjusting for age and CCI (OR 0.15; p = 0.02). After RP, 68% patients were continent. Median 90-days PSA after RP was 0.12 ng/dL. CP and OM-free survival at 7 years were 50% and 79%, respectively. The 7-years OM-free survival rates were 93 vs. 75% for men treated with vs. without MDT (p = 0.04). At regression analyses, MDT after surgery was associated with a 70% decreased mortality rate (HR 0.27, p = 0.04).

CONCLUSIONS

RP appeared to represent a safe and feasible option in omPCa. RARP reduced the risk of severe complications. Integrating MDT with surgery in the context of a multimodal treatment might improve survival in selected omPCa patients.

Impact of next-generation hormonal agents on treatment patterns among patients with metastatic hormone-sensitive prostate cancer: a real-world study from the United States, five European countries and Japan

BACKGROUND

Until five years ago, the metastatic hormone-sensitive prostate cancer (mHSPC) treatment landscape was dominated by the use of androgen deprivation therapy (ADT) alone. However, novel hormonal agents (NHAs) and chemotherapy are now approved for male patients with mHSPC. This study aimed to understand the impact NHA approvals had on mHSPC real-world treatment patterns and to identify the key factors associated with NHA or chemotherapy (± ADT) usage vs ADT alone.

METHODS

Data were collected from the Adelphi Prostate Cancer Disease Specific Programme (DSP)™, a point-in-time survey of physicians and their consulting patients conducted in the United States (US), five European countries (France, Germany, Italy, Spain, and the United Kingdom), and Japan between January and August 2020. Data were analysed using descriptive statistics for individual countries, regions, and all countries combined. Pairwise analyses were used to further investigate differences between treatment groups at global level.

RESULTS

336 physicians provided data on 1195 mHSPC patients. Globally, at data collection, the most common mHSPC regimen initiated first was ADT alone (47%), followed by NHAs (± ADT) (31%, of which 21% was abiraterone, 8% was enzalutamide, and 2% was apalutamide) and chemotherapy (± ADT) (19%). The highest rates of ADT alone usage were observed in Japan (78%) and Italy (66%), and the lowest in Spain (34%) and in the US (36%). Our results showed that clinical decision making was driven by patient fitness, compliance, tolerance of adverse events, and balance of impact on quality of life vs overall survival.

CONCLUSIONS

This real-world survey offered early insights into the evolving mHSPC treatment paradigm. It showed that in 2020, ADT alone remained the most common initial mHSPC therapy, suggesting that physicians may prefer using treatments which they are familiar and have experience with, despite clinical trial evidence of improved survival with NHAs or chemotherapy (± ADT) vs ADT alone. Results also indicated that physicians prescribed specific mHSPC treatments primarily based on the following criteria: patient preference, disease burden/severity, and the performance status and comorbidities of the patient. To fully appreciate the rapidly changing mHSPC treatment landscape and monitor NHA uptake, additional real-world studies are required.

Radiation therapy with curative intention in men with de novo metastatic prostate carcinoma: shoot'em all!

BACKGROUND

About 5% of prostate cancer cases are metastatic at diagnoses. Radiotherapy of both primary tumor and secondary lesions can be, in addition to systemic treatments, a radical alternative for selected patients.

MATERIALS AND METHODS

Patients with de novo prostate carcinoma with bone or lymph node metastases were retrospectively reviewed. All patients received moderate hypofractionated IMRT/VMAT up to 63 Gy in 21 daily fractions of 3 Gy to prostate and metastases with neoadjuvant and concurrent androgen deprivation therapy (ADT). According to known advances some patients also received abiraterone, enzalutamide, or docetaxel.

RESULTS

Between 2015-2020, we attended 26 prostate cancer patients (median age 69.5 years, range 52-84) with simultaneous oligometastases [mean 2.1 metastases, median 1.5 metastases (range 1-6)]. Eighteen patients (69%) presented lymph node metastases, 4 (15.5%) bone metastases and 4 (15.5%) both lymph node and bone metastases. With a median follow-up of 15.5 months (range 3-65 months), 16 patients (62%) are alive and tumor free while 10 (38%) are alive with tumor. Four patients (17%) developed tumor progression, out of irradiated area in all cases, with a median time to progression of 43.5 months (range 27-56 months). Actuarial progression-free survival (PFS) rates at 12 and 24 months were 94.1% and 84.7%, respectively. No grade > 2 acute or late complications were recorded.

CONCLUSIONS

Simultaneous directed radical hypofractionated radiation therapy for prostate and metastases is feasible, well tolerated and achieves an acceptable PFS rate. However, further studies with longer follow-up are necessary to definitively address these observations.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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