MicroRNA expression characterizes oligometastasis(es). PLoS One. 2011;6:e28650. [PMID: 22174856 PMCID: PMC3236765 DOI: 10.1371/journal.pone.0028650]

Detecting Metastatic Patterns of Oligometastatic Breast Cancer: A Comparative Analysis of 18F-FDG PET/CT and Conventional CT Imaging

Metastasis-directed therapy has the potential to improve progression-free and overall survival in oligometastatic disease (OMD). For breast cancer, however, randomized trials have failed so far to confirm this finding. Because the concept of metastasis-directed therapy in OMD is highly dependent on the accuracy of the imaging modality, we aimed to assess the impact of 18F-FDG PET/CT on the definition of OMD in breast cancer patients. Methods: Eighty patients with a total of 150 18F-FDG PET/CT images (between October 2006 and January 2022) were enrolled in this retrospective study at the Technical University of Munich. The inclusion criteria were OMD, defined as 1-5 distant metastases, at the time of 18F-FDG PET/CT. For the current study, we systemically compared the metastatic pattern on 18F-FDG PET/CT with conventional CT. Results: At the time of 18F-FDG PET/CT, 21.3% of patients (n = 32) had a first-time diagnosis of metastatic disease, 40.7% (n = 61) had a previous history of OMD, and 38% (n = 57) had a previous history of polymetastatic disease. In 45.3% of cases, the imaging modality (18F-FDG PET/CT vs. conventional CT) had an impact on the assessment of whether OMD was present. An identical metastatic pattern was observed in only 32% of cases.18F-FDG PET/CT detected additional metastases in 33.3% of cases, mostly in the nonregional lymph node system. Conclusion: The use of 18F-FDG PET/CT had a substantial impact on the definition of OMD and detection of metastatic pattern in breast cancer. Our results emphasize the importance of establishing a standardized definition for imaging modalities in future trials and clinical practices related to metastasis-directed therapy in breast cancer patients.

Surgery for Oligometastatic Pancreatic Cancer: Defining Biologic Resectability

Pancreatic ductal adenocarcinoma (PDAC) is most often metastatic at diagnosis. As systemic therapy continues to improve alongside advanced surgical techniques, the focus has shifted toward defining biologic, rather than technical, resectability. Several centers have reported metastasectomy for oligometastatic PDAC, yet the indications and potential benefits remain unclear. In this review, we attempt to define oligometastatic disease in PDAC and to explore the rationale for metastasectomy. We evaluate the existing evidence for metastasectomy in liver, peritoneum, and lung individually, assessing the safety and oncologic outcomes for each. Furthermore, we explore contemporary biomarkers of biological resectability in oligometastatic PDAC, including radiographic findings, biochemical markers (such as CA 19-9 and CEA), inflammatory markers (including neutrophil-to-lymphocyte ratio, C-reactive protein, and scoring indices), and liquid biopsy techniques. With careful consideration of existing data, we explore the concept of biologic resectability in guiding patient selection for metastasectomy in PDAC.

Navigating Breast Cancer Oligometastasis and Oligoprogression: Current Landscape and Future Directions

PURPOSE

We examine the potential for curative approaches among metastatic breast cancer (MBC) patients by exploring the recent literature on local ablative therapies like surgery and stereotactic body radiation therapy (SBRT) in patients with oligometastatic (OM) breast cancer. We also cover therapies for MBC patients with oligoprogressive (OP) disease.

KEY FINDINGS

Surgery and SBRT have been studied for OM and OP breast cancer, mainly in retrospective or non-randomized trials. While many studies demonstrated favorable results, a cooperative study and single-institution trial found no support for surgery/SBRT in OM and OP cases, respectively.

CONCLUSION

While there is interest in applying local therapies to OM and OP breast cancer, the current randomized data does not back the routine use of surgery or SBRT, particularly when considering the potential for treatment-related toxicities. Future research should refine patient selection through advanced imaging and possibly explore these therapies specifically in patients with hormone receptor-positive or HER2-positive disease.

Metastases-directed local therapies (MDT) beyond genuine oligometastatic disease (OMD): Indications, endpoints and the role of imaging

To further personalise treatment in metastatic cancer, the indications for metastases-directed local therapy (MDT) and the biology of oligometastatic disease (OMD) should be kept conceptually apart. Both need to be vigorously investigated. Tumour growth dynamics - growth rate combined with metastatic seeding efficiency - is the single most important biological feature determining the likelihood of success of MDT in an individual patient, which might even be beneficial in slowly developing polymetastatic disease. This can be reasonably well assessed using appropriate clinical imaging. In the context of considering appropriate indications for MDT, detecting metastases at the edge of image resolution should therefore suggest postponing MDT. While three to five lesions are typically used to define OMD, it could be argued that countability throughout the course of metastatic disease, rather than a specific maximum number of lesions, could serve as a better parameter for guiding MDT. Here we argue that the unit of MDT as a treatment option in metastatic cancer might best be defined not as a single procedure at a single point in time, but as a series of treatments that can be delivered in a single or multiple sessions to different lesions over time. Newly emerging lesions that remain amenable to MDT without triggering the start of a new systemic treatment, a change in systemic therapy, or initiation of best supportive care, would thus not constitute a failure of MDT. This would have implications for defining endpoints in clinical trials and registries: Rather than with any disease progression, failure of MDT would only be declared when there is progression to polymetastatic disease, which then precludes further options for MDT.

Radiotherapy in the management of lung oligometastases

In recent years, the development of both medical imaging and new systemic agents (targeted therapy and immunotherapy) have revolutionized the field of oncology, leading to a new entity: oligometastatic disease. Adding local treatment of oligometastases to systemic treatment could lead to prolonged survival with no significant impact on quality of life. Given the high prevalence of lung oligometastases and the new systemic agents coming with increased pulmonary toxicity, this article provides a comprehensive review of the current state-of-art for radiotherapy of lung oligometastases. After reviewing pretreatment workup, the authors define several radiotherapy regimen based on the localization and size of the oligometastases. A comment on the synergistic combination of medical treatment and radiotherapy is also made, projecting on future steps in this specific clinical setting.

Isolated pulmonary metastases in pancreatic ductal adenocarcinoma: a review of current evidence

Despite recent advances in cancer therapeutics, pancreatic ductal adenocarcinoma (PDAC) remains a lethal disease with a 5-year overall survival of only 10%. Since either at or within a few months of diagnosis, most patients with PDAC will present with metastatic disease, a more individualized approach to select patients who may benefit from more aggressive therapy has been suggested. Although studies have reported improved survival in PDAC and isolated pulmonary metastasis (ISP) compared to extrapulmonary metastases, such findings remain controversial. Furthermore, the added benefit of pulmonary metastasectomy and other lung-directed therapies remains unclear. In this review, we discuss the metastatic pattern of PDAC, evaluate the available evidence in the literature for improved survival in PDAC and ISP, evaluate the evidence for the added benefit of pulmonary metastasectomy and other lung-directed therapies, identify prognostic factors for survival, discuss the biological basis for the reported improved survival and identify areas for further research.

Research protocol to identify progression and death amongst patients with metastatic hormone-sensitive prostate cancer treated with available treatments: PIONEER IMI's "big data for better outcomes" program

Androgen deprivation therapy-based with or without first-generation anti-androgens, was the standard of care for patients with metastatic hormone-sensitive prostate cancer (mHSPC) for decades. However, the development of docetaxel chemotherapy and new androgen receptor-targeted agents, abiraterone acetate and prednisolone, apalutamide , enzalutamide and darolutamide (in combination with docetaxel chemotherapy) has proven that combination of treatments is more effective. Recently, intensification therapy, so-called "triplets", have emerged in the armamentarium of mHSPC treatment. Metastatic disease is a clinical state that remains poorly understood. The optimal diagnostic and management of patients with mHSPC are changing thanks to the development of new imaging techniques and therapies. The primary objective of this study is to develop and validate a predictive model for the occurrence of symptomatic progression, initiation of new treatments and death amongst patients with mHSPC treated with one of the approved treatment plans, on characteristics present at admission.

Defining oligometastatic pancreatic cancer: a systematic review and critical synthesis of consensus

BACKGROUND

Small retrospective series suggest that local consolidative treatment (LCT) may improve survival in oligometastatic pancreatic ductal adenocarcinoma (PDAC). However, no uniform definition of oligometastatic disease (OMD) in PDAC exists; this impedes meaningful conclusions.

PATIENTS AND METHODS

A systematic literature search using PubMed, Web of Science, and Cochrane CENTRAL registries for studies and protocols reporting on definitions and/or LCT of OMD in PDAC was performed. The primary endpoint was the definition of OMD. Levels of agreement were categorized as consensus (≥75% agreement between studies), fair agreement (50%-74%), and absent/poor agreement (<50%).

RESULTS

After screening of 5374 abstracts, the full text of 218 studies was assessed, of which 76 were included in the qualitative synthesis. The majority of studies were retrospective (n = 66, 87%), two were prospective studies and eight were study protocols. Studies investigated mostly liver (n = 38, 51%) and lung metastases (n = 15, 20%). Across studies, less than one-half (n = 32, 42%) reported a definition of OMD, while 44 (58%) did not. Involvement was limited to a single organ (consensus). Additional criteria for defining OMD were the number of lesions (consensus), metastatic site (poor agreement), metastatic size (poor agreement), treatment possibilities (poor agreement), and biomarker response (poor agreement). Liver OMD could involve three or fewer lesions (consensus) and synchronous disease (fair agreement), while lung metastases could involve two or fewer lesions and metachronous disease (consensus). The large majority of studies were at a high risk of bias or did not include any control groups.

CONCLUSION

Definitions of OMD were not used or varied widely between studies hampering across-study comparability and highlighting an unmet need for a consensus. The present study is part of a multistep process that aims to develop an interdisciplinary consensus on OMD in pancreatic cancer.

Oligometastatic Prostate Cancer Treated with Stereotactic Body Radiation Therapy: The Role of Three-Dimensional Tumour Volume in Patient Survival

AIMS

The definition of oligometastatic prostate cancer (OPCa) is currently based solely on the maximum number of detectable metastases, as there are no validated biomarkers available. The aim of this study was to identify novel predictive factors for OPCa patients who underwent metastases-directed therapy.

MATERIALS AND METHODS

This monocentre, retrospective study included consecutive OPCa patients with a maximum of five metastases in up to two organs, detected with choline- or PSMA-positron emission tomography, who were treated with metastases-directed stereotactic body radiation therapy. Endpoints were overall survival and progression-free survival, assessed with Kaplan-Meier analysis. Univariate and multivariable Cox regression was carried out to evaluate the association between clinical factors and survival outcomes.

RESULTS

Between 2009 and 2021, 163 patients and 320 metastases were treated with 226 stereotactic body radiation therapy courses. The median three-dimensional metastatic tumour volume was 4.1 cm3, with a range from 0.01 to 233.4 cm3. In total, 87 (53.4%), 21 (12.9%) and 55 (33.7%) metastases were classified as cN1, cM1a and cM1b, respectively. The median follow-up was 28.5 months. The rates of overall survival at 1, 3 and 5 years were 89.5% (95% confidence interval 83.4-93.4), 74.9% (95% confidence interval 66.1-81.7) and 57.2% (95% confidence interval 45.8-67.1), respectively. Multivariable analysis showed that overall survival reduced with the increase in three-dimensional total tumour volume (hazard ratio 1.93, 95% confidence interval 1.06-3.52; P = 0.030) and confirmed a significant difference between cN1 versus cM1a-b disease (hazard ratio 1.81, 95% confidence interval 1.01-3.25; P = 0.046). The cut-off value of total volume correlated with the highest risk of death was 20 cm3 (hazard ratio 2.37, 95% confidence interval 1.34-4.18; P = 0.003). The median progression-free survival was 17.8 months, with 1-, 3- and 5-year rates of 63.7% (95% confidence interval 55.4-70.9), 31.5% (95% confidence interval 22.8-40.6) and 24.7% (95% confidence interval 16.0-34.3).

CONCLUSIONS

This study identified three-dimensional total tumour volume and the site of oligometastases as significant predictors of survival in OPCa patients treated with metastases-directed therapy. These parameters can potentially be used to personalised treatment and improve patient outcome.

Oligo-Metastatic Disease in Oncology: Exploring the Limits and the Potential of Genetic Assessment

Oligo-metastatic disease (OMD) in the field of oncology denotes a distinct subset of metastatic tumors characterized by less aggressive biological behavior and extended survival times in comparison to their widely metastatic counterparts. While there is a general consensus regarding the existence of OMD, there remains a lack of widely accepted criteria for its a priori identification at the time of presentation. This review delves into the concept of OMD, placing a particular emphasis on the significance of understanding the limitations and potential of genetic assessments. It explores how these aspects are crucial in advancing our comprehension of this phenomenon. In a rapidly advancing era of precision medicine, understanding the intricacies of OMD opens up exciting possibilities for tailored treatment approaches. By elucidating the genetic underpinnings and dynamic nature of this condition, we stand to improve patient outcomes and potentially shift the paradigm of metastatic cancer management.

Oligometastatic Disease (OMD): The Classification and Practical Review of Prospective Trials

Oligometastatic disease (OMD) is currently known as an intermediate state of cancer, characterized by a limited number of systemic metastatic lesions for which local ablative therapy could be curative. Indeed, data from multiple clinical trials have illustrated an increase in overall survival (OS) for cancer patients when local ablative therapy was included in the systemic adjuvant therapy. Given that no driver and somatic mutations specific to OMD are currently established, the diagnosis of OMD is mainly based on the results of X-ray studies. In 2020, 20 international experts from the European Society for Radiotherapy and Oncology (ESTRO) and the European Organization for Research and Treatment of Cancer (EORTC) developed a comprehensive system for the characterization and classification of OMD. They identified 17 OMD characteristics that needed to be assessed in all patients who underwent radical local treatment. These characteristics reflect the tumor biology and clinical features of the disease underlying the development of OMD independently of the primary tumor type and the number of metastatic lesions. In particular, the system involves the characteristics of the primary tumor (e.g., localization, histology, TNM stage, mutational status, specific tumor markers), clinical parameters (e.g., disease-free interval, treatment-free interval), therapies (e.g., local, radical or palliative treatment, the numbers of the therapeutic regimens), and type of OMD (e.g., invasive). Based on the aforementioned criteria, an algorithm was introduced into the clinic to classify OMDs collectively according to their nomenclature. A history of polymetastatic disease (PMD) prior to OMD is used as a criterion to delineate between induced OMD (previous history of PMD after successful therapy) and genuine OMD (no history of PMD). Genuine OMD is divided into two states: recurrent OMD (i.e., after a previous history of OMD) and de novo OMD (i.e., a first newly diagnosed oligometastatic disease). de novo OMD is differentiated into synchronous and metachronous forms depending on the length of time from the primary diagnosis to the first evidence of OMD. In the case of synchronous OMD, this period is less than 6 months. Lastly, metachronous and induced OMD are divided into oligorecurrence, oligoprogression, and oligopersistence, depending on whether OMD is firstly diagnosed during an absence (oligo recurrence) or presence (oligoprogression or oligopersistence) of active systemic therapy. This classification and nomenclature of OMD are evaluated prospectively in the OligoCare study. In this article, we present a practical review of the current concept of OMD and discuss the available prospective clinical trials and potential future directions.

Metastasis-directed therapy for oligometastases in breast cancer

The concept of oligometastases was first proposed to describe a disease state between localized cancer and extensive metastasis. After the emergence of variations in the definition of oligometastasis, in April 2020 the European Society for Radiotherapy and Oncology and the European Organization for Research and Treatment of Cancer defined oligometastases as the presence of one to five metastatic lesions that can be safely treated. However, the pathogenesis of oligometastases remains unknown, and it is uncertain which patients will benefit from metastasis-directed therapy. Breast cancer with oligometastases is generally managed with systemic therapy. Retrospective studies have suggested that the addition of metastasis-directed therapy, such as surgery, radiofrequency ablation and stereotactic body radiation therapy, may increase overall survival in breast cancer patients with oligometastases, but as yet there have been no prospective studies. Phase II trials of stereotactic body radiation therapy or fractionated irradiation for oligometastases of breast cancer have demonstrated impressive rates of local control and overall survival. Although the efficacy of stereotactic body radiation therapy in the SABR-COMET was largely anticipated, it is noteworthy that only 18% of the patient population had breast cancer. For this reason, various trials were planned or are being conducted globally to investigate the efficacy of metastasis-directed therapy for oligometastases of breast cancer. Metastasis-directed therapy for oligometastases has been shown to be effective, and stereotactic body radiation therapy and other therapies are commonly used internationally and are considered to be safe. However, the efficacy of metastasis-directed therapy for oligometastases has not yet been proven. The results of future clinical trials are thus eagerly awaited.

Local treatment in oligometastasis from breast cancer: an overview

Oligometastasic breast cancer (OMBC) consists of breast cancer patient with a limited number of systemic metastases (≤ 5), all of them candidates for local ablative treatment with the intention of achieving long-term control of the metastasis and, eventually, an increase in survival The first consensus for the management of patients with oligometastatic breast cancer (OMBC) was published in 2007, establishing that a more aggressive multidisciplinary strategy is recommended in order to increase the survival while maintaining a good quality of life. The current scientific evidence is based on observational studies, mainly retrospective, systematic reviews and meta-analyses, and only a randomized nonexclusive study of oligometastatic (OM) published. All trials with Stereotactic Body Radiation Therapy (SBRT) in OM cancer have shown excellent tolerance and good local control, although first trials on Lung SBRT did not prove so excellent tolerance and had some deaths due to bronchus irradiation and secondary hemoptysis. There are multiple ongoing studies researching the benefit of SBRT in oligometastatic breast cancer. Despite the lack of impact on survival seen in the NRG BR-002 Trial, SBRT probably allows the delay of the systemic treatment until progression, and so, improves the quality of life of patients. We have to wait for the results of the ongoing and future studies for clarification of the role of local treatment in OMBC.

Focal therapy for primary tumor and metastases in de novo or recurrent oligometastatic prostate cancer: current standing and future perspectives

PURPOSE

Focal therapy (FT) is gaining increasing acceptance in the management of localized prostate cancer particularly due to its favorable safety. Preliminary evidence suggests advantageous utilization of local treatment in the field of oligometastatic prostate cancer (OMPC). Since data on the utilization of FT in OMPC are scarce, we sought to summarize available evidence.

METHODS

For this narrative comprehensive review, we employed PubMed®, Web of Science™, Embase®, Scopus®, and clinicaltrial.gov databases and Google web search engine to seek peer-reviewed articles, published abstracts from international congresses, and ongoing trials in the English language using the terms "prostate cancer", "oligometastatic", "hormone-sensitive", "focal therapy", "focal treatment", "cryotherapy", "ablation", "cancer" as well as "metastasis-directed therapy. We focused on relevant publications on FT utilized in OMPC targeting the primary or metastatic sites as well as completed and ongoing clinical trials.

RESULTS

Growing evidence points to distinct differences in the biologic behavior and molecular signaling processes of OMPC as compared to polymetastatic disease (PMPC). No established biomarkers are available to accurately identify OMPC yet, while several candidates are currently under investigation. The evolution of molecular imaging is set to aid in selecting patients benefitting most from local management. Differences between OMPC and PMPC should be considered when designing the optimal therapeutic strategy. While efficacy data for FT in comparison to standard care in OMPC are scarce, longer progression-free survival and time to castration resistance have been demonstrated for bone metastatic prostate cancer with the primary tumor treated by cryosurgery followed by androgen deprivation therapy (ADT) compared to ADT alone.

CONCLUSION

Ongoing research efforts are eagerly awaited to better characterize OMPC and establish customized strategies for patients with this condition.

Oligometastases: Characterizing the Role of Epigenetic Regulation of Epithelial-Mesenchymal Transition

The "oligometastasis" hypothesis proposes that metastases exist as a spectrum and are not always disseminated. According to this theory, a subset of patients with metastatic disease could benefit from aggressive local therapies. However, the identification of patients most likely to exhibit an oligometastatic phenotype remains challenging. Recent literature focusing on basic and translational studies has identified novel epigenetic regulators of epithelial-mesenchymal transition (EMT) and the emergence of a spectrum of metastatic behavior. Herein, we review these scientific advances and suggest that the spectrum of metastatic virulence produced by these epigenetic mechanisms broadly contributes to the emergence of clinically evident "oligometastases." Epigenetic regulation of EMT programs can result in a spectrum of cell trajectories (e.g., quasi-mesenchymal and highly mesenchymal states) with differential propensity to develop metastases. We propose that quasi-mesenchymal cell states may be associated with a polymetastatic phenotype, whereas highly mesenchymal cell states may be associated with a more oligometastatic phenotype. The mechanisms governing epigenetic regulation of EMT and its array of intermediate states are multifaceted and may contribute to the development of the metastatic spectrum observed clinically. Within this context, translational studies that support the role of EMT and its epigenetic regulation are discussed. Continued translation of these mechanistic discoveries into novel biomarkers may help optimally select patients most likely to exhibit an oligometastatic phenotype and benefit from aggressive local therapies, such as surgery, radiotherapy, and other ablative procedures.

Local Therapies for Metastatic Sarcoma: Why, When, and How?

Management of patients with advanced sarcoma has been evolving in recent decades, from a one-fit-all perspective to a more refined, personalized, and multidisciplinary approach. In parallel, the evolution of local therapies (radiotherapy, surgical and interventional radiology techniques) has contributed to the improvement of survival of patients with advanced sarcoma. In this article, we review the evidence regarding local treatments in advanced sarcoma, as well as its integration with systemic therapies, to provide the reader a wider and deeper perspective on the management of patients with metastatic sarcoma.

Unravelling oligometastatic disease from the perspective of radiation and medical oncology. Part I: non-small cell lung cancer and breast cancer

Oligometastatic disease (OMD) defines a cancer status that is intermediate between localized and widely spread metastatic disease, and can be treated with curative intent. While diagnostic imaging tools have considerably improved in recent years, unidentified micrometastases can still evade current detection techniques, allowing the disease to progress. The various OMD scenarios are mainly defined by the number of metastases, the biological and molecular tumour profiles, and the timing of the development of metastases. Increasing knowledge has contributed to the earlier and improved detection of OMD, underlining the importance of early disease control. In view of increasing OMD detection rates in current real-world clinical practice and the lack of standardized evidence-based guidelines to treat this cancer status, a board of experts from the Spanish Societies of Radiation Oncology (SEOR) and Medical Oncology (SEOM) organized a series of sessions to update the current state-of-the-art on OMD from a multidisciplinary perspective, and to discuss how results from clinical studies might translate into promising treatment options. This expert review series summarizes what is known and what it is pending clarification in the context of OMD in the scenarios of non-small cell lung cancer and breast cancer (Part I), and prostate cancer and colorectal cancer (Part II), aiming to offer specialists a pragmatic framework to help improve patient management.

The oligometastatic setting in HNSCC: A critical review by the Rete Oncologica Piemonte e Valle d'Aosta multidisciplinary team

INTRODUCTION

The oligometastatic disease is a low burden metastatic disease that might still benefit from curable treatment. Squamous cell carcinoma of the head and neck (HNSCC) is a complex group of malignancies, with high rates of loco-regional recurrences. Distant metastases are less frequent, and a single or few deposits are often observed (oligometastatic disease). The optimal management of oligometastatic HNSCC remains to be defined.

MATERIALS AND METHODS

Key references were derived from a PubMed query. Hand searching and clinicaltrials.gov were also used.

RESULTS

This paper contains a narrative report and a critical discussion of the available evidence on the management of oligometastatic HNSCC patients, with a focus on metastasis-directed therapy (MDT), particularly stereotactic ablative radiotherapy (SABR).

CONCLUSIONS

in line with literature data, the multidisciplinary evaluation emerged as the key element in the management of oligometastatic HNSCC patients.

Outcome of patients with biochemical recurrence of prostate cancer after PSMA PET/CT-directed radiotherapy or surgery without systemic therapy

BACKGROUND

Radiotherapy (RT) and surgery are potential treatment options in patients with biochemical recurrence (BCR) following primary prostate cancer treatment. This study examines the value of prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT)-informed surgery and RT in patients with BCR treated without systemic therapy.

METHODS

This is a post-hoc subgroup analysis of a prospective clinical trial. Inclusion criteria were: histologically proven prostate cancer at initial curative-intent treatment, BCR after primary treatment with curative intent, having five or fewer lesions identified on [¹⁸F]DCFPyL PET/CT, and treatment with either PET/CT-directed RT or surgery without systemic therapy. The biochemical progression-free survival after PSMA ligand PET/CT-directed RT and surgery was determined. Uni- and multivariate Cox regression analyses were performed for the association of patients' characteristics, tumor-specific variables, and PSMA PET/CT imaging results with biochemical progression at the last follow-up.

RESULTS

Fifty-eight patients (30 in surgery and 28 in radiotherapy groups) met the inclusion criteria. A total of 87 PSMA-positive lesions were detected: 16 local recurrences (18.4%), 54 regional lymph nodes (62.1%), 6 distant lymph nodes (6,8%), and 11 osseous lesions (12.7%). A total of 85.7% (24 of 28) and 70.0% (21 of 30) of patients showed a ≥ 50% decrease in prostate-specific antigen (PSA) levels after RT and surgery, respectively. At a median follow-up time of 21 months (range, 6-32 months), the median biochemical progression-free survival was 19 months (range, 4 to 23 months) in the radiotherapy group, as compared with 16.5 months (range, 4 to 28 months) in the surgery group. On multivariate Cox regression analysis, the number of PSMA positive lesions (2-5 lesions compared to one lesion), and the anatomic location of the detected lesions (distant metastasis vs. local relapse and pelvic nodal relapse) significantly correlated with biochemical progression at the last follow-up, whereas other clinical, tumor-specific, and imaging parameters did not.

CONCLUSIONS

This study suggests that RT or surgery based on [¹⁸F]DCFPyL PET/CT are associated with high PSA response rates. The number and site of lesions detected on the PSMA PET/CT were predictive of biochemical progression on follow-up. Further studies are needed to assess the impact of targeting these sites on patient relevant outcomes.

TRIAL REGISTRATION

Registered September 14, 2016; NCT02899312; https://clinicaltrials.gov/ct2/show/NCT02899312.

Oligo-Metastatic Cancers: Putative Biomarkers, Emerging Challenges and New Perspectives

Some cancer patients display a less aggressive form of metastatic disease, characterized by a low tumor burden and involving a smaller number of sites, which is referred to as "oligometastatic disease" (OMD). This review discusses new biomarkers, as well as methodological challenges and perspectives characterizing OMD. Recent studies have revealed that specific microRNA profiles, chromosome patterns, driver gene mutations (ERBB2, PBRM1, SETD2, KRAS, PIK3CA, SMAD4), polymorphisms (TCF7L2), and levels of immune cell infiltration into metastases, depending on the tumor type, are associated with an oligometastatic behavior. This suggests that OMD could be a distinct disease with specific biological and molecular characteristics. Therefore, the heterogeneity of initial tumor burden and inclusion of OMD patients in clinical trials pose a crucial methodological question that requires responses in the near future. Additionally, a solid understanding of the molecular and biological features of OMD will be necessary to support and complete the clinical staging systems, enabling a better distinction of metastatic behavior and tailored treatments.

Assessment of oligometastasis status of prostate cancer following combined robot-assisted radical prostatectomy and androgen deprivation versus androgen deprivation therapy alone using PSA percentage decline rate

Objective

To compare the tumor control in prostate cancer patients with oligo-metastasis following combined robot-assisted radical prostatectomy and androgen deprivation versus androgen deprivation therapy alone based on total prostate-specific antigen (tPSA) assessment.

Methods

Medical data of a total of 18 prostate cancer patients with oligometastasis administered in The First Affiliated Hospital of Nanchang University from March 2017 to March 2018 were prospectively collected. 10 patients received a combined therapy of robot-assisted radical prostatectomy and pharmaceutical androgen deprivation (RARP+ADT group), while 8 patients received pharmaceutical androgen deprivation therapy alone (ADT group). Then demographic characteristics, prostate volume, tumor characteristics and tPSA data were analysised and compared. Statistical analysis was performed using t-test for continuous variables and Pearson chi-square test or Fisher's exact test for categorical variables.

Results

No significant difference was found in patients' age (p = 0.075), prostate volume (p = 0.134) and number of bone metastasis (p = 0.342). Pre-treatment Gleason score was significantly lower in RA group (p = 0.003). Patients in RARP+ADT group had significantly lower pre-treatment tPSA (p = 0.014), while no statistical difference was noted in reexamined tPSA (p = 0.140) on follow-up. No statistical difference was noted in tPSA decline rates (declined tPSA value per day) in RARP+ADT and ADT group (8.1 ± 4.7 verse 7.5 ± 8.0 ng/ml/d, p = 0.853). However, tPSA percentage decline rate (declined tPSA percentage per day) was significantly higher in RARP+ADT group (11.6 ± 1.5%/d verses 2.9 ± 2.2%/d, p< 0.001). Immediate urinary continence was achieved in 9 patients (90%) upon removal of urethral catheter on post-operative day 7 in RARP+ADT group.

Conclusion

ADT alone and in combination with RARP both provide effective tumor control in patients suffering from prostate cancer with oligometastasis. ADT combined with RARP exhibited significant advantage in PSA percentage decline rate without compromising patients' urinary continence. Long-term tumor control requires further follow-up.

A Precise Approach for Radiotherapy of Breast Cancer

Radiotherapy is an integral part of the multidisciplinary management of breast cancer (BC). There have been multiple recent advances in the delivery of radiotherapy, reviewed with a critical discussion of the evidence from trials investigating adjuvant ultra-hypofractionation and partial breast irradiation for early-stage BC, and the locoregional management of lymph nodes in locally advanced BC. Multiple precision medicine-based approaches have been developed as prognostic and/or predictive for BC patients and identifying biomarkers of radioresistance could help identify patients that may benefit from dose-escalated radiotherapy or radiosensitizers. Radiotherapy after breast reconstruction is an area of current controversy in the field, and we evaluated the decision-making considerations in this situation. The oligometastatic state is an emerging field for many cancer sites based on recent trials investigating ablative radiotherapy for oligometastatic BC. This chapter is an overview of radiotherapy for BC, with a focus on recent advances in early-stage, locally advanced, and oligometastatic disease.

Management of Patients with Recurrent and Metachronous Oligometastatic Prostate Cancer in the Era of PSMA PET

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) scans have higher sensitivity and specificity for detecting lymph nodes or metastatic disease relative to conventional imaging in prostate cancer staging. Since its FDA approval and incorporation into treatment guidelines, the use of PSMA PET has increased in patients undergoing initial staging, those with recurrence after initial definitive treatment, and patients with metastatic disease. Although the early detection of metastatic lesions is changing disease management, it is unclear whether this impact on management translates into clinical benefit. This review will summarize evidence pertaining to the change in patient management due to PSMA PET use and will discuss the implications of PSMA PET on treatment decisions in prostate cancer, particularly in the settings of biochemical recurrence and metachronous oligometastatic disease.

Oligometastatic Prostate Cancer: Current Status and Future Challenges

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

The Management of Oligometastases in Non-small Cell Lung Cancer - is Stereotactic Ablative Radiotherapy now Standard of Care?

Oligometastatic non-small cell lung cancer encompasses a number of distinct clinical scenarios with a pattern of limited tumour burden on imaging. Delivering local ablative therapy to individual metastatic lesions may assist in disease modification and contribute to improved outcomes. We review the published randomised clinical trials that support the implementation of stereotactic ablative radiotherapy as a standard of care in certain oligometastatic non-small cell lung cancer clinical scenarios, and highlight the current knowledge gaps and areas of ongoing research.

Long-Term Outcomes and Genetic Predictors of Response to Metastasis-Directed Therapy Versus Observation in Oligometastatic Prostate Cancer: Analysis of STOMP and ORIOLE Trials

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The initial STOMP and ORIOLE trial reports suggested that metastasis-directed therapy (MDT) in oligometastatic castration-sensitive prostate cancer (omCSPC) was associated with improved treatment outcomes. Here, we present long-term outcomes of MDT in omCSPC by pooling STOMP and ORIOLE and assess the ability of a high-risk mutational signature to risk stratify outcomes after MDT. The primary end point was progression-free survival (PFS) calculated using the Kaplan-Meier method. High-risk mutations were defined as pathogenic somatic mutations within ATM, BRCA1/2, Rb1, or TP53. The median follow-up for the whole group was 52.5 months. Median PFS was prolonged with MDT compared with observation (pooled hazard ratio [HR], 0.44; 95% CI, 0.29 to 0.66; P value < .001), with the largest benefit of MDT in patients with a high-risk mutation (HR high-risk, 0.05; HR no high-risk, 0.42; P value for interaction: .12). Within the MDT cohort, the PFS was 13.4 months in those without a high-risk mutation, compared with 7.5 months in those with a high-risk mutation (HR, 0.53; 95% CI, 0.25 to 1.11; P = .09). Long-term outcomes from the only two randomized trials in omCSPC suggest a sustained clinical benefit to MDT over observation. A high-risk mutational signature may help risk stratify treatment outcomes after MDT.

Oligometastatic breast cancer: Dissecting the clinical and biological uniqueness of this emerging entity. Can we pursue curability?

Metastatic breast cancer represents an incurable condition, however, the increasing interest towards the oligometastatic entity is now challenging this assumption. Up to 20% of patients with metastatic breast cancer present with oligometastatic disease, which refers to metastatic breast cancer presenting or recurring with limited metastatic burden. In the last years, progressive advancements in imaging techniques, the growing availability of minimally invasive locoregional treatments, alongside the increasing expectations from a patient perspective, have contributed to rising the awareness towards this emerging entity. In the present work we comprehensively reviewed available evidence regarding oligometastatic breast cancer, focusing on clinical and biological notions virtually supporting the adoption of a curative approach when treating this condition. We also discussed main areas of uncertainties, providing a research agenda that may guide and fine-tune the future investigation in this field.

Oligometastatic Disease in the Liver: The Role of Interventional Oncology

Oligometastatic disease represents a clinically discrete intermediate stage of cancer progression and is an expanding area of research. While surgical metastatectomy has been recognized for decades as an effective treatment option in select patients, options for metastasis-directed therapy have broadened in scope with advancements in the armamentarium of non- and minimally invasive modalities. Recent preclinical studies investigating the immunology surrounding liver metastases demonstrate treatment resistance to immunotherapy in affected patients and show how locoregional therapy has the ability to overcome this resistance. In this paper, we review advancements in our understanding of oligometastatic disease, metastasis-directed therapy, effect of liver metastasis on response to immunotherapy, and the burgeoning role of image-guided interventions in complementing cancer immunotherapy at the exciting crossroads of interventional oncology and immuno-oncology.

Local Consolidative Therapy for Oligometastatic Non-Small Cell Lung Cancer

In the last 20 years, significant strides have been made in our understanding of the biological mechanisms driving disease pathogenesis in metastatic non-small cell lung cancer (NSCLC). Notably, the development and application of predictive biomarkers as well as refined treatment regimens in the form of chemoimmunotherapy and novel targeted agents have led to substantial improvements in survival. Parallel to these remarkable advancements in modern systemic therapy has been a growing recognition of "oligometastatic disease" as a distinct clinical entity-defined by the presence of a controlled primary tumor and ≤5 sites of metastatic disease amenable to local consolidative therapy (LAT), with surgery or stereotactic ablative body radiotherapy (SABR). To date, three randomized studies have provided clinical evidence supporting the use of LAT/SABR in the treatment of oligometastatic NSCLC. In this review, we summarize clinical evidence from these landmark studies and highlight ongoing trials evaluating the use of LAT/SABR in a variety of clinical contexts along the oligometastatic disease spectrum. We discuss important implications and caveats of the available data, including considerations surrounding patient selection and application in routine clinical practice. We conclude by offering potential avenues for further investigation in the oligometastatic disease space.

Ways to improve breast cancer patients' management and clinical outcome: The 2020 Assisi Think Tank Meeting

We report on the third Assisi Think Tank Meeting (ATTM) on breast cancer, a brainstorming project which involved European radiation and clinical oncologists who were dedicated to breast cancer research and treatment. Held on February 2020, the ATTM aimed at identifying key clinical questions in current clinical practice and "grey" areas requiring research to improve management and outcomes. Before the meeting, three key topics were selected: 1) managing patients with frailty due to either age and/or multi-morbidity; 2) stereotactic radiation therapy and systemic therapy in the management of oligometastatic disease; 3) contralateral breast tumour prevention in BCRA-mutated patients. Clinical practice in these areas was investigated by means of an online questionnaire. In the lapse period between the survey and the meeting, the working groups reviewed data, on-going studies and the clinical challenges which were then discussed in-depth and subjected to intense brainstorming during the meeting; research protocols were also proposed. Methodology, outcome of discussions, conclusions and study proposals are summarized in the present paper. In conclusion, this report presents an in-depth analysis of the state of the art, grey areas and controversies in breast cancer radiation therapy and discusses how to confront them in the absence of evidence-based data to guide clinical decision-making.

Outcome of lung oligometastatic patients treated with stereotactic body irradiation

Purpose

The oligometastatic stage is an intermediate stage of cancer between the localized stage and polymetastatic stage. The prognosis of patients in this stage also appears to be intermediate. Lung stereotactic body radiotherapy is a possible tool for treating oligometastatic lung sites. The objective of our study was to evaluate the clinical outcomes in terms of local control, progression-free survival, overall survival, and toxicity of SBRT in oligometastatic patients with lung metastases from any solid primary tumor.

Materials and methods

Clinical records of consecutive lung oligometastatic patients treated between January 2010 and December 2020 for lung SBRT at 60 Gy in 3- or 8-fraction schedules and a controlled primary tumor were retrospectively analyzed.

Results

After a median follow-up of 20.3 months, local failure occurred for 14 lesions, 57 patients experienced lung progression, and 64 patients experienced disease progression. Overall survival rates at 1 and 2 years were 85.6 and 69.7%, respectively. Fifty-two patients experienced radiation pneumonitis, but only 2 patients were symptomatic and presented grade 2 late pneumonitis. No grade 3-4 toxicity was observed. ECOG 0 was the only prognostic factor for overall survival (HR = 3.5; 95% CI 3.2-3.8; p < 0.01).

Conclusion

SBRT with a 60-Gy schedule in 8 fractions is an effective and well-tolerated treatment for patients with lung oligometastases from any solid primary tumor.

Current treatment landscape for oligometastatic non-small cell lung cancer

The management of patients with advanced non-small cell lung carcinoma (NSCLC) has undergone major changes in recent years. On the one hand, improved sensitivity of diagnostic tests, both radiological and endoscopic, has altered the way patients are staged. On the other hand, the arrival of new drugs with antitumoral activity, such as targeted therapies or immunotherapy, has changed the prognosis of patients, improving disease control and prolonging survival. Finally, the development of radiotherapy and surgical and interventional radiology techniques means that radical ablative treatments can be performed on metastases in any location in the body. All of these advances have impacted the treatment of patients with advanced lung cancer, especially in a subgroup of these patients in which all of these treatment modalities converge. This poses a challenge for physicians who must decide upon the best treatment strategy for each patient, without solid evidence for one optimal mode of treatment in this patient population. The aim of this article is to review, from a practical and multidisciplinary perspective, published evidence on the management of oligometastatic NSCLC patients. We evaluate the different alternatives for radical ablative treatments, the role of primary tumor resection or radiation, the impact of systemic treatments, and the therapeutic sequence. In short, the present document aims to provide clinicians with a practical guide for the treatment of oligometastatic patients in routine clinical practice.

Surgical Management of Metastatic Breast Cancer: A Mini Review

Breast cancer with distant metastases is a systemic disease. While systemic therapies are the main treatment strategy, locoregional therapy for metastatic breast cancer (MBC) is generally palliative only. However, recent progress in systemic and local therapies has improved the prognosis of patients with MBC and some may expect long-term survival. More vigorous local therapies for MBC may, therefore, be clinically justified in selected patients. A number of clinical trials and studies have investigated the clinical significance of surgical therapy for primary tumors and distant metastases in patients with MBC. Four prospective randomized trials and multiple retrospective studies have investigated the benefit of surgical resection of primary lesions in patients with MBC, with conflicting results. There have been a number of case-control studies examining the impact of surgical resection of distant metastases, but the benefit of this approach in terms of survival is controversial because selection bias is unavoidable in retrospective studies. The present review discusses the state of the literature relating to local management of the primary breast cancer through surgical resection and surgical management of distant metastatic lesions including pulmonary and liver metastases with future perspectives.

Metastasis-Directed Radiation Therapy with Consolidative Intent for Oligometastatic Urothelial Carcinoma: A Systematic Review and Meta-Analysis

The management of patients with oligometastatic urothelial carcinoma (UC) represents an evolving field in uro-oncology, and the role of metastasis-directed therapies, including metastasectomy and metastasis-directed radiation therapy (MDRT), is gaining increasing attention. Herein, we summarize available evidence about the role of MDRT with consolidative intent in oligometastatic UC patients. A systematic review was performed in December 2021. Six studies involving 158 patients were identified. Most patients (n = 120, 90.2%) had a history of bladder cancer and the most frequent sites of metastases were lymph nodes (n = 61, 52.1%) followed by the lungs (n = 34, 29%). Overall, 144 metastases were treated with MDRT. Median follow-up ranged from 17.2 to 25 months. Local control rates ranged from 57% to 100%. Median Overall Survival (OS) ranged from 14.9 to 51.0 months and median progression-free survival ranged from 2.9 to 10.1 months. Rates of OS at one and two years ranged from 78.9% to 96% and from 26% to 63%, respectively. Treatment-related toxicity was recorded in few patients and in most cases a low-grade toxicity was evident. MDRT with consolidative intent represents a potential treatment option for selected patients with oligometastatic UC.

Oligoscore: a clinical score to predict overall survival in patients with oligometastatic disease treated with stereotactic body radiotherapy

BACKGROUND

to find clinical features that can predict prognosis in patients with oligometastatic disease treated with stereotactic body radiotherapy (SBRT).

MATERIAL AND METHODS

Patients with less than 5 metastases in less than 3 different body sites were included in the analysis. Various clinical and treatment parameters were analyzed to create a Cox proportional hazard model for Overall Survival (OS). Subsequently, significant variables were used to create a score.

RESULTS

997 patients were analyzed. Median OS was 2.61 years, 1 and 3 years OS was respectively 85% and 43%. Location of the primary tumor, performance status, site of irradiated metastases, presence of extratarget non irradiated lesions and RT dose were significant prognostic factors for OS. These parameters were used to create a score and to distinguish three different classes, with median OS of 5.67 years in low risk, 2.47 years in intermediate risk and 1.82 years in high risk group.

CONCLUSION

moving from easily accessible clinical parameters, a score was created to help the physician's decision about the better treatment or combination of treatments for the individual patient.

The Road to Dissemination: The Concept of Oligometastases and the Barriers for Widespread Disease

Over the last years, the oligometastatic disease state has gained more and more interest, and randomized trials are now suggesting an added value of stereotactic radiotherapy on all macroscopic disease in oligometastatic patients; but what barriers could impede widespread disease in some patients? In this review, we first discuss the concept of oligometastatic disease and some examples of clinical evidence. We then explore the route to dissemination: the hurdles a tumoral clone has to overtake before it can produce efficient and widespread dissemination. The spectrum theory argues that the range of metastatic patterns encountered in the clinic is the consequence of gradually obtained metastatic abilities of the tumor cells. Tumor clones can obtain these capabilities by Darwinian evolution, hence early in their genetic progression tumors might produce only a limited number of metastases. We illustrate selective dissemination by discussing organ tropism, the preference of different cancer (sub)types to metastasize to certain organs. Finally we discuss biomarkers that may help to distinguish the oligometastatic state.

Where Do We Stand in the Management of Oligometastatic Prostate Cancer? A Comprehensive Review

Simple Summary

Oligometastatic prostate cancer is an intermediate stage between localised and metastatic disease. Today, there are many advances in the diagnosis of this stage of the disease, with the appearance of new imaging techniques and treatments, thanks to the development of new modalities, both local and systemic therapies, the emergence of personalised medicine, and theragnostics.

Abstract

Oligometastatic prostate cancer (OMPC) is an intermediate state between localised disease and widespread metastases that includes a spectrum of disease biology and clinical behaviours. This narrative review will cover the current OMPC scenario. We conducted comprehensive English language literature research for original and review articles using the Medline database and grey literature through December 2021. OMPC is a unique clinical state with inherently more indolent tumour biology susceptible to multidisciplinary treatment (MDT). With the development of new imaging techniques, patients with OMPC are likely to be identified at an earlier stage, and the paradigm for treatment is shifting towards a more aggressive approach to treating potentially curable patients. Multimodal management is necessary to improve patient outcomes due to the combination of available therapies, such as local therapy of primary tumour, metastasis directed therapy or systemic therapy, to reduce tumour load and prevent further disease progression. Additional prospective data are needed to select patients most likely to benefit from a given therapeutic approach.

Stereotactic radiotherapy for oligometastases in the lymph nodes

Even though systemic therapy is standard treatment for lymph node metastases, metastasis-directed stereotactic radiotherapy (SRT ) seems to be a valid option in oligometastatic patients with a low disease burden.

Positron emission tomography-computed tomography (PET-CT ) is the gold standard for assessing metastases to the lymph nodes; co-registration of PET-CT images and planning CT images are the basis for gross tumor volume (GTV ) delineation. Appropriate techniques are needed to overcome target motion. SRT schedules depend on the irradiation site, target volume and dose constraints to the organs at risk (OARs) of toxicity. Although several fractionation schemes were reported, total doses of 48–60 Gy in 4–8 fractions were proposed for mediastinal lymph node SRT, with the spinal cord, esophagus, heart and proximal bronchial tree being the dose limiting OAR s. Total doses ranged from 30 to 45 Gy, with daily fractions of 7–12 Gy for abdominal lymph nodes, with dose limiting OARs being the liver, kidneys, bowel and bladder. SRT on lymph node metastases is safe; late side effects, particularly severe, are rare.

The Role of the CDK4/6 Inhibitor Ribociclib in Locally Advanced and Oligometastatic Hormone Receptor Positive, Her2 Negative, Advanced Breast Cancer: Case Series and Review of the Literature

The recent addition of cyclin-dependent kinase 4 (CDK4) and CDK6 inhibitors to endocrine therapy has remarkably improved the outcome of patients affected with hormone receptor positive (HR+), human epidermal grow factor receptor 2 negative (HER2 -) advanced breast cancer (ABC). Ribociclib showed to be effective across most subgroups, regardless of the number and the site of metastasis. Up to 10% of patients with ABC, reported an oligometastatic condition, recently defined as a slow-volume metastatic disease with limited number and size of metastatic lesions (up to 5 and not necessarily in the same organ), potentially amenable for local treatment, aimed at achieving a complete remission status. Despite the wide use of CDK4/6 inhibitors in HR+, HER2-, ABC treatment, data regarding both locally advanced, inoperable disease and oligometastatic conditions are still poor. We reported a review and case series of HR+, HER2-, ABC patients treated with ribociclib as first-line therapy, for a locally advanced and oligometastatic conditions, reporting an impressive response and good safety profile.

Stereotactic Body Radiation Therapy in Patients with Oligometastatic Disease: Clinical State of the Art and Perspectives

Stereotactic body radiation therapy (SBRT) is a form of radiation therapy (RT) in which a small number of high doses of radiation are delivered to a target volume using highly sophisticated equipment. Stereotactic body radiation therapy is crucial in two cancer stages: early primary cancer and oligometastatic disease, with the goal of inducing complete cancer remission in both. This treatment method is commonly used to treat a variety of disease types. Over the years, a growing body of clinical evidence on the use of SBRT for the treatment of primary and metastatic tumors has accumulated, with efficacy and safety demonstrated in randomized clinical trials. This article will review the technical and clinical aspects of SBRT according to disease type and clinical indication.

Molecular Mechanisms Related with Oligometastatic Prostate Cancer-Is It Just a Matter of Numbers?

During the last decade, the body of knowledge regarding the oligometastatic state has increased exponentially. Several molecular frameworks have been established, aiding our understanding of metastatic spread caused by genetically unstable cells that adapt to a tissue environment which is distant from the primary tumor. In the current narrative review, we provide an overview of the current treatment landscape of oligometastatic cancer, focusing on the current biomarkers used in the identification of true oligometastatic disease and highlighting the impact of molecular imaging on stage shift in different scenarios. Finally, we address current and future directions regarding the use of genetic and epigenetic targeting treatments in oligometastatic prostate cancer.

Recent Advances in the Management of Hormone-Sensitive Oligometastatic Prostate Cancer

After primary treatment for prostate cancer with either radical prostatectomy or radiotherapy, a significant proportion of patients are at risk of developing metastases. In recent years, a deeper understanding of the underlying biology together with improved imaging techniques and the advent of new therapeutic options including metastases-directed therapies and new drugs have revolutionized the management of low-burden metastatic disease, also known as oligometastatic state. The purpose of this narrative review is to report the recent developments in the management of hormone-sensitive oligometastatic prostate cancer patients.

Efficacy and Safety of Local Radiotherapy to All Oligometastatic Sites in Elderly Patients with Metachronous Oligometastatic Cancers After Initial Treatment for the Primary Tumor

Background and Purpose

This study aimed to investigate the efficacy and safety of maintenance therapy combined with local radiotherapy at all oligometastatic sites (LRTOS) in elderly patients with metachronous oligometastatic cancers (MOC).

Patients and Methods

A total of 242 elderly patients with MOC (≤5 metastases) and primary tumor well controlled after definitive treatment was retrospectively analyzed between August 2014 and February 2020 at Beijing Geriatric Hospital and Air Force General Hospital. Patients were divided into maintenance therapy group (maintenance therapy alone) and local radiotherapy group (maintenance therapy combined with LRTOS).

Results

There were 86 patients in the local radiotherapy group and 156 patients in the maintenance therapy group. The median length of follow-up was 36 months (range, 8.0–62 months). Median overall survival (mOS) was 25 months (95% CI: 21.1–28.9) in the local radiotherapy group and 16 months (95% CI: 14.5–17.6) in the maintenance therapy group (p < 0.001). Multivariate analyses demonstrated that LRTOS (hazard ratio (HR) = 0.49, 95% confidence interval (CI): 0.35–0.67, p < 0.001), good Eastern Cooperative Oncology Group Performance Status (ECOG PS, HR = 0.69, 95% CI: 0.49–0.97, p = 0.032), longer duration between diagnosis of primary tumor and occurrence of progression (HR = 0.87, 95% CI: 0.78–0.97, p = 0.015), and subsequent systemic treatment (HR = 0.52, 95% CI: 0.38–0.72, p < 0.001) were independent predictors of good OS. In patients who did not receive subsequent systemic treatment, their mOS was 21 months (95% CI: 12.8–29.2) for those treated with LRTOS and 14 months (95% CI: 11.4–16.6) for those who did not receive local radiotherapy (p = 0.001). Further multivariate analysis showed that LRTOS was the only independent factor for predicting good OS (HR = 0.47, 95% CI: 0.26–0.83, p = 0.010). Patients with metachronous oligometastatic lung cancer, colorectal cancer, prostate cancer, and breast cancer had higher survival benefits following LRTOS. Most patients suffered from grade 1–2 toxicities, but no treatment-related death was recorded.

Conclusion

This retrospective study shows that elderly patients with MOC treated with LRTOS may have better survival outcomes.

Patient Selection for Local Aggressive Treatment in Oligometastatic Non-Small Cell Lung Cancer

Simple Summary

Since the first introduction of the oligometastatic state with a low burden of metastases in non-small cell lung cancer, accumulating evidence from retrospective and prospective studies has shown that a local aggressive, multimodality treatment may significantly improve the prognosis in these patients. Local aggressive treatment includes a systemic therapy of micrometastatic disease, as well as a radical resection of the primary tumor and surgical resection and/or radiation therapy of distant metastases. However, patient selection and treatment allocation remain a central challenge in oligometastatic disease. In this review, we aimed to address the current evidence on criteria for patient selection for local aggressive treatment in non-small cell lung cancer.

Abstract

One-fourth of all patients with metastatic non-small cell lung cancer presents with a limited number of metastases and relatively low systemic tumor burden. This oligometastatic state with limited systemic tumor burden may be associated with remarkably improved overall and progression-free survival if both primary tumor and metastases are treated radically combined with systemic therapy. This local aggressive therapy (LAT) requires a multidisciplinary approach including medical oncologists, radiation therapists, and thoracic surgeons. A surgical resection of the often advanced primary tumor should be part of the radical treatment whenever feasible. However, patient selection, timing, and a correct treatment allocation for LAT appear to be essential. In this review, we aimed to summarize and discuss the current evidence on patient selection criteria such as characteristics of the primary tumor and metastases, response to neoadjuvant or first-line treatment, molecular characteristics, mediastinal lymph node involvement, and other factors for LAT in oligometastatic NSCLC.

The concept of oligometastatic disease in gastric cancer: reality or fiction?

Positive results in the RENAISSANCE Trial will establish oligometastatic gastric cancer as a real independent entity where total surgical treatment will become the standard of care.