Recurrence pattern of stereotactic body radiotherapy in oligometastatic prostate cancer: a multi-institutional analysis

Whole pelvis vs. hemi pelvis elective nodal radiotherapy in patients with PSMA-positive nodal recurrence after radical prostatectomy - a retrospective multi-institutional propensity score analysis

PURPOSE

Despite growing evidence for bilateral pelvic radiotherapy (whole pelvis RT, WPRT) there is almost no data on unilateral RT (hemi pelvis RT, HPRT) in patients with nodal recurrent prostate cancer after prostatectomy. Nevertheless, in clinical practice HPRT is sometimes used with the intention to reduce side effects compared to WPRT. Prostate-specific membrane antigen positron emission tomography / computed tomography (PSMA-PET/CT) is currently the best imaging modality in this clinical situation. This analysis compares PSMA-PET/CT based WPRT and HPRT.

METHODS

A propensity score matching was performed in a multi-institutional retrospective dataset of 273 patients treated with pelvic RT due to nodal recurrence (214 WPRT, 59 HPRT). In total, 102 patients (51 in each group) were included in the final analysis. Biochemical recurrence-free survival (BRFS) defined as prostate specific antigen (PSA) < post-RT nadir + 0.2ng/ml, metastasis-free survival (MFS) and nodal recurrence-free survival (NRFS) were calculated using the Kaplan-Meier method and compared using the log rank test.

RESULTS

Median follow-up was 29 months. After propensity matching, both groups were mostly well balanced. However, in the WPRT group there were still significantly more patients with additional local recurrences and biochemical persistence after prostatectomy. There were no significant differences between both groups in BRFS (p = .97), MFS (p = .43) and NRFS (p = .43). After two years, BRFS, MFS and NRFS were 61%, 86% and 88% in the WPRT group and 57%, 90% and 82% in the HPRT group, respectively. Application of a boost to lymph node metastases, a higher RT dose to the lymphatic pathways (> 50 Gy EQD2α/β=1.5 Gy) and concomitant androgen deprivation therapy (ADT) were significantly associated with longer BRFS in uni- and multivariate analysis.

CONCLUSIONS

Overall, this analysis presents the outcome of HPRT in nodal recurrent prostate cancer patients and shows that it can result in a similar oncologic outcome compared to WPRT. Nevertheless, patients in the WPRT may have been at a higher risk for progression due to some persistent imbalances between the groups. Therefore, further research should prospectively evaluate which subgroups of patients are suitable for HPRT and if HPRT leads to a clinically significant reduction in toxicity.

Pattern of recurrence after stereotactic body radiotherapy of nodal lesions: a single-institution analysis

OBJECTIVES

Stereotactic body radiotherapy (SBRT) and/or single fraction stereotactic body radiosurgery (SRS) are effective treatment options for the treatment of oligometastatic disease of lymph nodes. Despite the encouraging local control rate, progression-free survival remains unfair due to relapses that might occur in the same district or at other sites. The recurrence pattern analysis after nodal local ablative RT (laRT) in oligometastatic patients is presented in this study.

METHODS

The pattern of failure of patients with nodal metastases who were recruited and treated with SBRT in the Destroy-1 or SRS in the Destroy-2 trials was investigated in this single-institution, retrospective analysis. The different relapsed sites following laRT were recorded.

RESULTS

Data on 190 patients who received SBRT or SRS on 269 nodal lesions were reviewed. A relapse rate of 57.2% (154 out of 269 nodal lesions) was registered. The pattern of failure was distant in 88 (57.4%) and loco-regional in 66 (42.6%) patients, respectively. The most frequent primary malignancies among patients experiencing loco-regional failure were genitourinary and gynaecological cancers. Furthermore, the predominant site of loco-regional relapse (62%) was the pelvic area. Only 26% of locoregional relapses occurred contra laterally, with 74% occurring ipsilaterally.

CONCLUSIONS

The recurrence rates after laRT for nodal disease were more frequent in distant regions compared to locoregional sites. The most common scenarios for locoregional relapse appear to be genitourinary cancer and the pelvic site. In addition, recurrences often occur in the same nodal station or in a nodal station contiguous to the irradiated nodal site.

ADVANCES IN KNOWLEDGE

Local ablative radiotherapy is an effective treatment in managing nodal oligometastasis. Despite the high local control rate, the progression free survival remains dismal with recurrences that can occur both loco-regionally or at distance. To understand the pattern of failure could aid the physicians to choose the best treatment strategy. This is the first study that reports the recurrence pattern of a significant number of nodal lesions treated with laRT.

Stereotactic Body Radiotherapy for Lymph-Nodal Oligometastatic Prostate Cancer: A Multicenter Retrospective Experience

Background: The favorable role of SBRT for lymph-nodal oligometastases from prostate cancer has been reported by several retrospective and prospective experiences, suggesting a more indolent natural history of disease when compared to patients with bone oligometastases. This retrospective multicenter study evaluates the outcomes of a cohort of patients treated with stereotactic body radiotherapy for lymph-nodal oligometastases. Methods: Inclusion criteria were up to five lymph-nodal oligometastases detected either with Choline-PET or PSMA-PET in patients naïve for ADT or already ongoing with systemic therapy and at least 6 Gy per fraction for SBRT. Only patients with exclusive lymph-nodal disease were included. The primary endpoint of the study was LC; a toxicity assessment was retrospectively performed following CTCAE v4.0. Results: A total of 100 lymph-nodal oligometastases in 69 patients have been treated with SBRT between April 2015 and November 2022. The median age was 73 years (range, 60-85). Oligometastatic disease was mainly detected with Choline-PET in 47 cases, while the remaining were diagnosed using PSMA-PET, with most of the patients treated to a single lymph-nodal metastasis (48/69 cases), two in 14 cases, and three in the remaining cases. The median PSA prior to SBRT was 1.35 ng/mL (range, 0.3-23.7 ng/mL). Patients received SBRT with a median total dose of 35 Gy (range, 30-40 Gy) in a median number of 5 (range, 3-6) fractions. With a median follow-up of 16 months (range, 7-59 months), our LC rates were 95.8% and 86.3% at 1 and 2 years. DPFS rates were 90.4% and 53.4%, respectively, at 1 and 2 years, with nine patients developing a sequential oligometastatic disease treated with a second course of SBRT. Polymetastatic disease-free survival (PMFS) at 1 and 2 years was 98% and 96%. Six patients needed ADT after SBRT for a median time of ADT-free survival of 15 months (range, 6-22 months). The median OS was 16 months (range, 7-59) with 1- and 2-year rates of both 98%. In multivariate analysis, higher LC rates and the use of PSMA-PET were related to improved DPFS rates, and OS was significantly related to a lower incidence of distant progression. No G3 or higher adverse events were reported. Conclusions: In our experience, lymph-nodal SBRT for oligometastatic prostate cancer is a safe and effective option for ADT delay with no severe toxicity.

PSMA-PET/CT-Based Stereotactic Body Radiotherapy (SBRT) in the Treatment of Uncomplicated Non-Spinal Bone Oligometastases from Prostate Cancer

BACKGROUND AND PURPOSE

Stereotactic body radiotherapy (SBRT) has a consolidated role in the treatment of bone oligometastases from prostate cancer (PCa). While the evidence for spinal oligometastases SBRT was robust, its role in non-spinal-bone metastases (NSBM) is not standardized. In fact, there was no clear consensus about dose and target definition in this setting. The aim of our study was to evaluate efficacy, toxicity, and the pattern of relapse in SBRT delivered to NSBM from PCa.

MATERIALS AND METHODS

From 2016 to 2021, we treated a series of oligo-NSBM from PCa with ⁶⁸Ga-PSMA PET/CT-guided SBRT. The primary endpoint was local progression-free survival (LPFS). The secondary endpoints were toxicity, the pattern of intraosseous relapse, distant progression-free survival (DPFS), polimetastases-free survival (PMFS), and overall survival (OS).

RESULTS

a total of 150 NSBM in 95 patients were treated with 30-35 Gy in five fractions. With a median follow-up of 26 months, 1- and 3 years LPFS was 96.3% and 89%, respectively. A biologically effective dose (BED) ≥ 198 Gy was correlated with improved LPFS (p = 0.007). Intraosseous relapse occurred in eight (5.3%) cases. Oligorecurrent disease was associated with a better PMFS compared to de novo oligometastatic disease (p = 0.001) and oligoprogressive patients (p = 0.007). No grade ≥ 3 toxicity occurred.

CONCLUSION

SBRT is a safe and effective tool for NSBM from PCa in the oligometastatic setting. Intraosseous relapse was a relatively rare event. Predictive factors of the improved outcomes were defined.

1.5 T MR-Guided Daily Adapted SBRT on Lymph Node Oligometastases from Prostate Cancer

Introduction: The aim of our study was to evaluate the efficacy and toxicity of a daily adaptive MR-guided SBRT on 1.5 T MR-linac in patients affected by lymph node oligometastases from PCa. Materials and Methods: The present study is a prospective observational study conducted in a single institution (protocol n°: MRI/LINAC n. 23748). Patients with oligometastatic lymph nodes from PCa treated with daily adaptive MR-guided SBRT on 1.5 T MR-linac were included in the study. There was a minimum required follow-up of 3 months after SBRT. The primary end-point was local progression-free survival (LPFS). The secondary end-points were: nodal progression-free survival (NPFS), progression-free survival (PFS), and toxicity. Results: A total of 118 lymph node oligometastases from PCa were treated with daily adaptive 1.5 T MR-guided SBRT in 63 oligometastatic patients. Of the patients, 63.5% were oligorecurrent and 36.5% were oligoprogressive. The two-year LPFS was 90.7%. The median NPFS was 22.3 months and the 2-year NPFS was 46.5%. Receiving hormone therapy before SBRT was correlated with a lower NPFS at the multivariate analysis (1 y NPFS 87.1% versus 42.8%; p = 0.002-HR 0.199, 95% CI 0.073-0.549). Furthermore, the oligorecurrent state during ADT was correlated with a lower NPFS than was the oligoprogressive state. The median PFS was 10.3 months and the 2-year PFS was 32.4%. Patients treated with hormone therapy before SBRT had a significantly lower 1-year PFS the others (28% versus 70.4%; p = 0.01-HR 0.259, 95% CI 0.117-0.574). No acute and late toxicities occurred during treatment. Conclusions: The present study is the largest prospective study of 1.5 T lymph node SBRT on MR-linac in patients with PCa. Lymph node SBRT by 1.5 T MR-linac provides high local control rates with an excellent toxicity profile.

Oligometastatic Prostate Cancer: A Comparison between Multimodality Treatment vs. Androgen Deprivation Therapy Alone

Background: We compared multimodality treatment (MMT, defined as robot-assisted radical prostatectomy (RARP) with androgen deprivation therapy (ADT), with or without adjuvant radiotherapy (RT)) vs. ADT alone in oligometastatic prostate cancer (OPC) patients. Methods: From 2010 to 2018, we identified 74 patients affected by cM1a-b OPC (≤5 metastases). Kaplan−Meier (KM) plots depicted cancer-specific mortality (CSM), disease progression, metastatic castration-resistant PC (mCRPC), and time to second-line systemic therapy rates. Multivariable Cox regression models (MCRMs) focused on disease progression and mCRPC. Results: Forty (54.0%) MMT and thirty-four (46.0%) ADT patients were identified. On KM plots, higher CSM (5.9 vs. 37.1%; p = 0.02), mCRPC (24.0 vs. 62.5%; p < 0.01), and second-line systemic therapy (33.3 vs. 62.5%; p < 0.01) rates were recorded in the ADT group. No statistically significant difference was recorded for disease progression. ForMCRMs adjusted for the metastatic site and PSA, a higher mCRPC rate was recorded in the ADT group. No statistically significant difference was recorded for disease progression. Treatment-related adverse events occurred in 5 (12.5%) MMT vs. 15 (44.1%) ADT patients (p < 0.01). Conclusions: MMT was associated with lower CSM, mCRPC, and second-line therapy rates. A lower rate of treatment-related adverse events was recorded for the MMT group.

Stereotactic body radiotherapy (SBRT) and concomitant systemic therapy in oligoprogressive breast cancer patients

Breast cancer is a heterogenous disease with a deep tailoring level. Evidence is accumulating on the role of stereotactic body radiotherapy (SBRT) in the management of oligometastatic disease, however this is limited in breast cancer. The aim of the present study is to show the effectiveness of SBRT in delaying the switch to a subsequent systemic treatment in oligoprogressive breast cancer patients. Retrospective analysis from two Institutions. Primary endpoint: time to next systemic treatment (NEST). Secondary endpoints: freedom from local progression (FLP), time to the polymetastatic conversion (tPMC) and overall survival (OS). One-hundred fifty-three (153) metastases in 79 oligoprogressive breast cancer patients were treated with SBRT. Median follow-up 24 months. Median NEST 8 months. Predictive factor of NEST at the multivariate analysis (MVA) was the number of treated oligometastases (HR 1.765, 95%CI 1.322-2.355; p = < 0.01). Systemic treatment after SBRT was changed in 29 patients for polymetastatic progression and in 10 patients for oligometastatic progression < 6 months after SBRT. The 2-year FLP in the overall population was 86.7%. A biological effective dose (BED) > 70Gy₁₀ was associated with improved FLP (90% versus 74.2%). The median tPMC was 10 months. At the MVA the only factors significantly associated with tPMC were the number of oligometastases (HR 1.172, 95%CI 1.000-1.368; p = 0.03), and the local control of the treated metastases (HR 2.726, CI95% 1.108-6.706; p = 0.02). SBRT can delay the switch to a subsequent systemic treatment, however patient selection is necessary. Several predictive factors for treatment tailoring have been identified.

Radiotherapy in oligometastatic prostate cancer-a pattern of care survey among members of the German Society for Radiation Oncology (DEGRO)

Purpose

Due to improved imaging, oligometastatic prostate cancer (OMPC) is diagnosed more frequently. Growing evidence shows that patients with a limited number of metastases benefit from primary-directed radiotherapy (PDT) as well as from metastasis-directed radiotherapy (MDT). This survey investigates the current treatment practice for OMPC among German-speaking radiation oncologists.

Methods

Members of the German Society for Radiation Oncology (Deutsche Gesellschaft für Radioonkologie [DEGRO]) were surveyed regarding their current treatment practice via an anonymous online questionnaire sent by email. The survey included six general items and 14 specific items regarding treatment characteristics. Questionnaires with at least 50% of questions completed were considered for further analysis.

Results

A total of 204 responses were received (15% response rate), 167 were considered for further analysis. Most respondents stated to be specialized in treating prostate cancer patients and to treat 10–30 patients with OMPC per annum; 97% considered PSMA-PET/CT necessary to define oligometastatic disease. Opinions differed regarding the use of systemic therapies: 63% of the respondents aimed to defer systemic therapy using radiotherapy in OMPC, whereas 37% considered systemic therapy necessary. In the setting of synchronous OMPC, 97% recommended PDT with or without a combination of MDT and/or systemic therapy. For metachronous nodal or bone oligometastatic recurrence, 98 and 99%, respectively, would opt for MDT. The majority would combine MDT with systemic therapy in patients with metachronous oligorecurrence. Respondents recommended normofractionation, hypofractionation, and SBRT for lymph node metastases in 49, 27, and 24%, respectively. No consensus existed regarding the field size for MDT of lymph node metastases. Most respondents preferred > 5 fractions for treatment of bone metastases.

Conclusion

Local radiotherapy for PDT and MDT is routinely used among respondents of this survey, representing 12% of all German-speaking radiation oncologists. The timing of systemic therapy, fractionation schedules, and field sizes are handled differently and remain an area of active investigation.

Postoperative moderately hypofractionated radiotherapy in prostate cancer: a mono-institutional propensity-score-matching analysis between adjuvant and early-salvage radiotherapy

AIM

To evaluate the impact of moderately hypofractionated postoperative radiotherapy (RT) in prostate cancer (PCa).

MATERIALS AND METHODS

The data of 304 surgically resected PCa patients were analyzed. One hundred and five patients underwent adjuvant RT (aRT), 77 early-savage RT (esRT), and 123 salvage RT (sRT). Biochemical relapse-free survival (BRFS), progression-free survival (PFS) and toxicity were analyzed. A propensity score matching (PSM) was performed to account for potential confounders between aRT and esRT groups.

RESULTS

The median follow-up was 33 months. Three-year BRFS and PFS were 82 and 85.2%, respectively, in the overall population. At the multivariate analysis, Gleason score and hormone therapy were factors independently correlated with BRFS and PFS. After PSM, there was no difference in BRFS and PFS between aRT and esRT patients. Severe toxicity was represented by grade 3 urinary incontinence (3.5%) and urgency (1%), and aRT correlated with increased any-grade acute toxicity. Severe grade 3 gastrointestinal late toxicity occurred in 1.3% of cases.

CONCLUSION

Postoperative moderately hypofractionated RT achieved acceptable disease control rate and demonstrated no increased or unexpected toxicity. Future prospective studies should evaluate the role of postoperative RT in patients with unfavorable disease characteristics.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Local Therapies in Oligometastatic and Oligoprogressive Prostate Cancer

Oligometastatic disease was originally defined by Hellman and Weichselbaum as an intermediate-state existing between locally confined and widely disseminated malignancy, whose natural history could be positively impacted with systemic and importantly local therapies such as radiation. Currently oligometastatic prostate cancer (OPCa) is defined clinically by lesion enumeration and several subgroups exist: de novo (synchronous) oligometastatic disease present at initial diagnosis, oligorecurrent (metachronous) disease arising after definitive therapy to the prostate, and oligoprogressive disease where isolated lesions progress in a background of otherwise stable disease. In this review we highlight current knowledge and the potential future of local therapies, such as radiation to the primary prostate and metastasis-directed therapy (MDT), in the disease management of OPCa for all 3 subgroups. In addition, we examine more recent studies classifying the patterns of failure and natural history of OPCa following treatment with local therapies. Finally, while current clinical definitions of OPCa dominate, we introduce studies attempting to elucidate a more biological definition of OPCa to allow for improved selection of patients to treat with local therapies and to better inform precision combination approaches with systemic therapy.

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 prostatic cancer recurrence: role of salvage lymph node dissection (sLND) and radiation therapy-stereotactic body radiation therapy (RT-SBRT)

PURPOSE OF REVIEW

Metastases directed therapy (MDT) is an increasingly utilized modality in patients with oligometastatic prostate cancer (OMPC) recurrence. The purpose of our review is to discuss the recent literature on the safety and oncologic outcomes of this treatment approach.

RECENT FINDINGS

Metastases directed therapy, in particular, stereotactic body radiation therapy (SBRT) and salvage lymph node dissection (sLND), has shown promising efficacy in patients with OMPC. Many case series report favorable outcomes with MDT as compared to hormonal deprivation therapy alone or surveillance. Of the few case series investigating the use of MDT as part of a multimodality approach in castrate-resistant OMPC, more favorable outcomes in comparison to the use of systemic treatment alone are reported.

SUMMARY

With the recent advances in imaging techniques, particularly molecular imaging, management of OMPC has progressed rapidly in the last few years. The feasibility and benefits of MDT in OMPC have been demonstrated in prospective and retrospective series. Further prospective studies investigating the role of MDT to define optimal patient subgroups and management strategies are warranted.

Stereotactic body radiotherapy for oligometastatic castration sensitive prostate cancer using 1.5 T MRI-Linac: preliminary data on feasibility and acute patient-reported outcomes

OBJECTIVES

To report preliminary data on feasibility and patient-reported outcomes following PSMA-PET/CT guided SBRT by means of 1.5 T MRI-Linac.

METHODS AND MATERIALS

Between October 2019 and April 2020, twenty consecutive castration sensitive oligorecurrent prostate cancer patients were enrolled in an ethical committee approved prospective observational study (Protocol n. XXXX) and treated with PSMA-PET/CT guided SBRT by means of 1.5 T MRI-Linac (Unity, Elekta AB, Stockholm, Sweden). The mean delivered dose was 35 Gy in 5 fractions. Clinicians reported toxicity was prospectively collected according to Common Terminology Criteria for Adverse Events v5.0. Quality of life (QoL) assessment was performed using EORTC-QLQ C30 questionnaires administered at baseline, end of treatment and at first follow-up.

RESULTS

Twenty-five lesions in 20 castration sensitive oligorecurrent patients were treated: the most commonly treated anatomic sites were nodal (n = 16) and pelvic bone (n = 9). Median PSA-value preMRI guided SBRT was 1.16 ng/mL (range, 0.27-8.9), whereas median PSA value at first follow-up after SBRT was 0.44 ng/mL (range, 0.06-8.15). At first follow-up, for 16 patients showing detectable PSA, PSMA-PET/CT was performed detecting, respectively, in 6 cases partial response and in 10 cases complete response. In the remaining cases, PSA-value was undetectable after SBRT. Radiotherapy treatment was safe and well tolerated according to the PROMs. No acute G2 or higher toxicities were recorded.

CONCLUSIONS

The current series represent the largest one exploring the feasibility and patient-reported outcomes following PSMA-PET/CT guided SBRT by means of 1.5 T MRI-Linac. The preliminary findings here reported are encouraging in terms of effectiveness and tolerability.

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.

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.

68Ga-PSMA-PET/CT-based radiosurgery and stereotactic body radiotherapy for oligometastatic prostate cancer

Background

Androgen deprivation therapy (ADT) remains the standard therapy for patients with oligometastatic prostate cancer (OMPC). Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT)-based stereotactic body radiotherapy (SBRT) is emerging as an alternative option to postpone starting ADT and its associated side effects including the development of drug resistance. The aim of this study was to determine progression free-survival (PFS) and treatment failure free-survival (TFFS) after PSMA-PET/CT-based SBRT in OMPC patients. The efficacy and safety of single fraction radiosurgery (SFRS) and ADT delay were investigated.

Methods

Patients with ≤5 metastases from OMPC, with/without ADT treated with PSMA-PET/CT-based SBRT were retrospectively analyzed. PFS and TFFS were primary endpoints. Secondary endpoints were local control (LC), overall survival (OS) and ADT-free survival (ADTFS).

Results

Fifty patients with a total of 75 metastases detected by PSMA-PET/CT were analyzed. At the time of SBRT, 70% of patients were castration-sensitive. Overall, 80% of metastases were treated with SFRS (median dose 20 Gy, range: 16–25). After median follow-up of 34 months (range: 5–70) median PFS and TFFS were 12 months (range: 2–63) and 14 months (range: 2–70), respectively. Thirty-two (64%) patients had repeat oligometastatic disease. Twenty-four (48%) patients with progression underwent second SBRT course. Two-year LC after SFRS was 96%. Grade 1 and 2 toxicity occurred in 3 (6%) and 1 (2%) patients, respectively. ADTFS and OS rates at 2-years were 60.5% and 100%, respectively. In multivariate analysis, TFFS significantly improved in patients with time to first metastasis (TTM) >36 months (p = 0.01) and PSA before SBRT ≤1 ng/ml (p = 0.03).

Conclusion

For patients with OMPC, SBRT might be used as an alternative to ADT. This way, the start/escalation of palliative ADT and its side effects can be deferred. Metastases treated with PSMA-PET/CT-based SFRS reached excellent LC with minimal toxicity. Low PSA levels and longer TTM predict elongated TFFS.

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.

Phase II trial of high dose stereotactic body radiation therapy for lymph node oligometastases

Lymph nodes are common sites of oligometastases for several primaries. Stereotactic body radiation therapy (SBRT) represents an effective treatment but no consensus exists regarding dose and fractionation. Aim of this trial was to evaluate safety and efficacy of high-dose SBRT. We included patients with 1 to 3 lymph node metastases. Primary end-point was safety, while secondary end-points were in-field local control (LC), out-field lymph nodal progression free survival (LPFS), distant metastasis free survival (DMFS), progression free survival (PFS) and overall survival (OS). 64 lesions in 52 patients were treated from 2015 to 2019. Most common primary tumor was genitourinary cancer (75%), in particular prostate cancer (65.4%). With a median follow-up of 24.4 months (range 3-49), treatment was very well tolerated, with only 4 (7.7%) patients reporting acute side effects, all classified as grade 1, in the form of pain, fatigue, nocturia and dysuria. No toxicity ≥ grade 2 were reported. Rates of LC at 1, 2 and 3 years were 97.9%, 82.1% and 82.1%. Male sex (HR 0.12, p value 0.014) was associated with improved LC. LPFS at 1, 2 and 3 years were 69.6%, 49.6% and 46.1%, respectively, and DMFS was 81.74%, 67.5% and 58.5%, respectively. Presence of lesions in other organs was correlated with inferior DMFS (HR 3.82, p = 0.042). PFS at 1, 2 and 3 years were 67.4%, 42.4% and 31.86%, respectively. OS at 1, 2 and 3 years were 97.3%, 94.2%, 84%, respectively and significantly correlated with in-field recurrence (HR 8.72, p = 0.000). Our prospective trial confirms safety and efficacy of SBRT in the management of lymph node metastases. Registered Clinical trial NCT02570399.

Prostate re-irradiation: current concerns and future perspectives

INTRODUCTION

To date, the optimal management of locally relapsed prostate cancer patients after an initial course of radiotherapy remains a matter of debate. In recent years, local approaches have been proposed as a therapeutic option, which may potentially delay the initiation of hormone therapy. In the case of external beam radiotherapy (EBRT), re-irradiation has been supported by growing evidence in the literature, mostly represented by extreme hypofractionated schedules delivered with stereotactic body radiotherapy (SBRT).

AREAS COVERED

We performed a systematic review of the literature using the PICO methodology to explore the available evidence regarding the use of EBRT in the setting of locally relapsed prostate cancer, both in terms of safety, tolerability and preliminary clinical outcomes.

EXPERT OPINION

Current literature data report the use of EBRT and particularly of SBRT for the safe and feasible re-treatment of locally recurrent prostate cancer after an initial treatment course of radiotherapy. When extreme hypofractionation is adopted, only occasional grade ≥3 late adverse events are reported. Despite the current lack of high-level evidence and the short follow-up, preliminary clinical outcomes are promising and allow clinicians to hypothesize further prospective studies to evaluate SBRT as an alternative to the early initiation of androgen-deprivation therapy.

Stereotactic Body Radiation Therapy in the Management of Oligometastatic and Oligoprogressive Bladder Cancer and Other Urothelial Malignancies

AIMS

Bladder cancer represents the most common type of urothelial carcinoma, with a median overall survival of 12.5-15 months in the case of metastatic disease. We evaluated the role of stereotactic body radiation therapy (SBRT) in the management oligometastatic urothelial cancer.

MATERIALS AND METHODS

Data on patients with a maximum of five metastases were collected from three institutions. Concomitant systemic therapy was allowed. End points were the local control of treated metastases, distant progression-free survival (PFS), overall PFS and overall survival.

RESULTS

Data for 82 lesions and 61 patients were included. The primary tumour was located in the bladder in 82% of patients, followed by kidney pelvis (11.5%). The most common treated site was lung (40.2%). Twenty-nine (47.5%) and 14 (23%) patients received systemic therapy before and during SBRT, respectively. The median BED10 value was 78.7 Gy. The median follow-up was 17.2 months. Rates of local control at 1 and 2 years were 92% and 88.9%, respectively, with correlation with systemic therapy before SBRT (hazard ratio 2.62, P = 0.034). Overall PFS at 1 and 2 years was 47.9% and 38.1%, respectively. The number of metastases was a predictive factor (hazard ratio 2.65, P = 0.008). The median overall survival was 25.6 months. Total dose (hazard ratio 0.93, P = 0.003) and BED10 (hazard ratio 0.97, P = 0.006) were correlated with overall survival. No grade ≥2 adverse events were reported.

CONCLUSIONS

SBRT represents an effective and safe treatment in metastatic urothelial carcinoma. Prospective randomised trials are necessary to better evaluate the benefit on delaying the onset of new systemic therapies.

Salvage radiotherapy in patients affected by oligorecurrent pelvic nodal prostate cancer

PURPOSE

Metastasis-directed therapy (MDT) is an investigational treatment option in patients with oligorecurrent prostate cancer (PCa). The aim of this retrospective study is to report oncologic outcome and toxicity of elective nodal radiotherapy (ENRT) in PCa patients affected by pelvic nodal oligorecurrence.

METHODS

41 consecutive patients were treated with salvage radiotherapy. At biochemical recurrence after primary treatment, oligorecurrent disease was detected by positron emission tomography (PET) in 94% of the patients. Image-guided intensity modulated radiation therapy (IMRT) was delivered using tomotherapy. 83% of the patients received androgen deprivation therapy (ADT) in combination with ENRT. Survival analysis was performed with Kaplan-Meier method, log-rank test was used to analyze associations between survival end-points and clinical parameters. Multivariate analysis was performed using Cox proportional hazards regression models. Toxicity was registered according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0.

RESULTS

The median at follow-up was 33.6 months. At 3 years, overall survival (OS), cancer-specific survival (CSS), and biochemical progression-free survival (b-PFS) were 89%, 92%, and 53%, respectively. At univariate analysis, all survival end-points were correlated with the number of positive pelvic lymph nodes at oligorecurrence (≤ 3 vs > 3). Biochemical-PFS was correlated with PSA (p = 0.034) and PSA doubling time (p = 0.004) at oligorecurrence. At multivariate analysis, no independent variable was statistically significant. No patient experienced grade ≥ 2 late toxicity after radiotherapy.

CONCLUSIONS

The number of metastatic lymph nodes and PSA doubling time seems to be important prognostic factors in the pelvic oligorecurrent setting. Salvage radiotherapy combined with short-course ADT might be a valid treatment strategy.

Stereotactic body radiotherapy (SBRT) can delay polymetastatic conversion in patients affected by liver oligometastases

PURPOSE

SBRT demonstrated to increase survival in oligometastatic patients. Nevertheless, little is known regarding the natural history of oligometastatic disease (OMD) and how SBRT may impact the transition to the polymetastatic disease (PMD).

METHODS

97 liver metastases in 61 oligometastatic patients were treated with SBRT. Twenty patients (33%) had synchronous oligometastases, 41 (67%) presented with metachronous oligometastases. Median number of treated metastases was 2 (range 1-5).

RESULTS

Median follow-up was 24 months. Median tPMC was 11 months (range 4-17 months). Median overall survival (OS) was 23 months (range 16-29 months). Cancer-specific survival predictive factors were having further OMD after SBRT (21 months versus 15 months; p = 0.00), and local control of treated metastases (27 months versus 18 months; p = 0.031). Median PFS was 7 months (range 4-12 months). Patients with 1 metastasis had longer median PFS as compared to those with 2-3 and 4-5 metastases (14.7 months versus 5.3 months versus 6.5 months; p = 0.041). At the last follow-up, 50/61 patients (82%) progressed, 16 of which (26.6%) again as oligometastatic and 34 (56%) as polymetastatic.

CONCLUSION

In the setting of oligometastatic disease, SBRT is able to delay the transition to the PMD. A proportion of patients relapse as oligometastatic and can be eventually evaluated for a further SBRT course. Interestingly, those patients retain a survival benefit as compared to those who had PMD. Further studies are needed to explore the role of SBRT in OMD and to identify treatment strategies able to maintain the oligometastatic state.