Oligo- and polymetastatic progression in lung metastasis(es) patients is associated with specific microRNAs

Stereotactic Body Radiotherapy for Oligometastasis: Opportunities for Biology to Guide Clinical Management

Oligometastasis refers to a state of limited metastatic disease burden, in which surgical or ablative treatment to all known visible metastases holds promise to extend survival or even effect cure. Stereotactic body radiotherapy is a form of radiation treatment capable of delivering a high biologically effective dose of radiation in a highly conformal manner, with a favorable toxicity profile. Enthusiasm for oligometastasis ablation, however, should be counterbalanced against the limited supporting evidence. It remains unknown to what extent (if any) ablation influences survival or quality of life. Rising clinical equipoise necessitates the completion of randomized controlled trials to assess this, several of which are underway. However, a lack of clear identification criteria or biomarkers to define the oligometastatic state hampers optimal patient selection.This narrative review explores the evolutionary origins of oligometastasis, the steps of the metastatic process at which oligometastases may arise, and the biomolecular mediators of this state. It discusses clinical outcomes with treatment of oligometastases, ongoing trials, and areas of basic and translational research that may lead to novel biomarkers. These efforts should provide a clearer, biomolecular definition of oligometastatic disease and aid in the accurate selection of patients for ablative therapies.

In Vivo Delivery and Therapeutic Effects of a MicroRNA on Colorectal Liver Metastases

Multiple therapeutic agents are typically used in concert to effectively control metastatic tumors. Recently, we described microRNAs that are associated with the oligometastatic state, in which a limited number of metastatic tumors progress to more favorable outcomes. Here, we report the effective delivery of an oligometastatic microRNA (miR-655-3p) to colorectal liver metastases using nanoscale coordination polymers (NCPs). The NCPs demonstrated a targeted and prolonged distribution of microRNAs to metastatic liver tumors. Tumor-targeted microRNA miR-655-3p suppressed tumor growth when co-delivered with oxaliplatin, suggesting additive or synergistic interactions between microRNAs and platinum drugs. This is the first known example of systemically administered nanoparticles delivering an oligometastatic microRNA to advanced metastatic liver tumors and demonstrating tumor-suppressive effects. Our results suggest a potential therapeutic strategy for metastatic liver disease by the co-delivery of microRNAs and conventional cytotoxic agents using tumor-specific NCPs.

The Role of Hypofractionated Radiotherapy in Prostate Cancer

PURPOSE OF REVIEW

It is now accepted that prostate cancer has a low alpha/beta ratio, establishing a strong basis for hypofractionation of prostate radiotherapy. This review focuses on the rationale for hypofractionation and presents the evidence base for establishing moderate hypofractionation for localised disease as the new standard of care. The emerging evidence for extreme hypofractionation in managing localized and oligometastatic prostate cancer is reviewed.

RECENT FINDINGS

The 5-year efficacy and toxicity outcomes from four phase III studies have been published within the last 12 months. These studies randomizing over 6000 patients to conventional fractionation (1.8-2.0 Gy per fraction) or moderate hypofractionation (3.0-3.4 Gy per fraction). They demonstrate hypofractionation to be non-inferior to conventional fractionation. Moderate hypofractionation for localized prostate cancer is safe and effective. There is a growing body of evidence in support of extreme hypofractionation for localized prostate cancer. Extreme hypofractionation may have a role in managing prostate oligometastases, but further studies are needed.

The changing role of radiation therapy in the management of oligometastatic disease

It is clear from surgical series that there are selected patients presenting with localised metastatic disease who can be cured by radical ablation of the metastasis. To date this has been limited to surgical resection but the evolution of stereotactic ablative body radiotherapy (SABR) has opened new opportunities. Hypofractionated radiation delivery in 1 to 5 fractions can achieve durable local control with low toxicity. The focus is now to develop robust biomarkers so that those with true oligometastatic and thereby potentially curable disease can be selected for this approach.

Lung metastases treated with stereotactic body radiotherapy: the RSSearch® patient Registry's experience

Objectives

To report overall survival and local control for patients identified in the RSSearch® Patient Registry with metastatic cancer to the lung treated with SBRT.

Methods

Seven hundred two patients were identified with lung metastases in the RSSearch® Registry. Of these patients, 577 patients had SBRT dose and fractionation information available. Patients were excluded if they received prior surgery, radiation, or radiofrequency ablation to the SBRT treated area. Between April 2004-July 2015, 447 patients treated with SBRT at 30 academic and community-based centers were evaluable for overall survival (OS). Three hundred four patients with 327 lesions were evaluable for local control (LC). All doses were converted to Monte Carlo equivalents and subsequent BED Gy₁₀ for dose response analysis.

Results

Median age was 69 years (range, 18–93 years). Median Karnofsky performance status (KPS) was 90 (range 25/75% 80–100). 49.2% of patients had prior systemic therapy. Median metastasis volume was 10.58 cc (range 25/75% 3.7–25.54 cc). Site of primary tumor included colorectal (25.7%), lung (16.6%), head and neck (11.4%), breast (9.2%), kidney (8.1%), skin (6.5%) and other (22.1%). Median dose was 50 Gy (range 25/75% 48–54) delivered in 3 fractions (range 25/75% 3–5) with a median BED of 100Gy₁₀ (range 25/75% 81–136).

Median OS for the entire group was 26 months, with actuarial 1-, 3-, and 5-year OS of 74.1%, 33.3, and 21.8%, respectively. Patients with head and neck and breast cancers had longer median OS of 37 and 32 months respectively, compared to colorectal (30 months) and lung (26 months) which corresponded to 3-year actuarial OS of 51.8 and 47.9% for head and neck and breast respectively, compared to 35.8% for colorectal and 31.2% for lung.

The median LC for all patients was 53 months, with actuarial 1-, 3-, and 5-year LC rates of 80.4, 58.9, and 46.3%, respectively. There was no difference in LC by primary histologic type (p = 0.49). Improved LC was observed for lung metastases that received SBRT doses of BED ≥100Gy₁₀ with 3-year LC rate of 77.1% compared to 45% for lung metastases treated with BED < 100Gy₁₀ (p = 0.01). Smaller tumor volumes (<11 cc) had improved LC compared to tumor volumes > 11 cc. (p = 0.005) Two-year LC rates for tumor volumes < 11 cc, 11–27 cc and > 27 cc were 72.9, 64.2 and 45.6%, respectively. This correlated with improved OS with 2-year OS rates of 62.4, 60.9 and 46.2% for tumor volumes < 11 cc, 11–27 cc and > 27 cc, respectively (p = 0.0023). In a subset of patients who received BED ≥100Gy₁₀, 2-year LC rates for tumor volumes < 11 cc, 11–27 cc and > 27 cc were 82.8, 58.9 and 68.6%, respectively (p = 0.0244), and 2-year OS rates were 66.0, 58.8 and 28.5%, respectively (p = 0.0081).

Conclusion

Excellent OS and LC is achievable with SBRT utilizing BED ≥100Gy₁₀ for lung metastases according to the RSSearch® Registry data. Patients with small lung metastases (volumes < 11 cc) had better LC and OS when using SBRT doses of BED ≥100Gy₁₀. Further studies to evaluate a difference, if any, between various tumor types will require a larger number of patients.

The expanding role of stereotactic body radiation therapy in oligometastatic solid tumors: What do we know and where are we going?

The spectrum hypothesis posits that there are distinct clinical states of metastatic progression. Early data suggest that aggressive treatment of more biologically indolent metastatic disease, characterized by metastases limited in number and destination organ, may offer an opportunity to alter the disease course, potentially allowing for longer survival, delay of systemic therapy, or even cure. The development of stereotactic body radiation therapy (SBRT) has opened new avenues for the treatment of oligometastatic disease. Early data support the use of SBRT for treating oligometastases in a number of organs, with promising rates of treated metastasis control and overall survival. Ongoing investigation is required to definitively establish benefit, determine the appropriate treatment regimen, refine patient selection, and incorporate SBRT with systemic therapies.

Unexpected long survival of brain oligometastatic non-small cell lung cancer (NSCLC) treated with multimodal treatment: a single-center experience and review of the literature

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Fifty percent of the cases are metastatic at diagnosis and about 20% develop brain metastasis. The brain involvement represents a negative prognostic factor. However, some patients could benefit from locoregional treatments of metastatic foci and experience an unexpected long survival or healing. In the previous years some classifications were proposed to identify patients' prognostic category, according to stage of the primary tumor, the timing of metastases occurrence (synchronous or metachronous) and the number of metastatic sites. Several data show a benefit in patients receiving resection of both the primary tumor and brain metastases. Whole brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS) are the selected options in most cases. Overall, literature data showed highly variable outcome, with an overall survival (OS) ranging from 5.9 to 68 months. No data from randomized and homogeneous trials are currently available. Therefore, a growing interest in this field is observed. Different trials investigating the effectiveness of local treatments and studies analyzing biological mechanisms are ongoing. In this report we analyze literature data and we explore the current field of study. Furthermore, we show a single institutional experience of multimodal management of stage IV NSCLC with brain metastases, experiencing an unexpected long survival. We conclude that a better knowledge of this subpopulation of patients and new studies in this field can lead to distinguish the patients who can benefit from local treatment from those with poor prognosis.

Advanced Animal Model of Colorectal Metastasis in Liver: Imaging Techniques and Properties of Metastatic Clones

Patients with a limited number of hepatic metastases and slow rates of progression can be successfully treated with local treatment approaches^1,2. However, little is known about the heterogeneity of liver metastases, and animal models capable of evaluating the development of individual metastatic colonies are needed. Here, we present an advanced model of hepatic metastases that provides the ability to quantitatively visualize the development of individual tumor clones in the liver and estimate their growth kinetics and colonization efficiency. We generated a panel of monoclonal derivatives of HCT116 human colorectal cancer cells stably labeled with luciferase and tdTomato and possessing different growth properties. With a splenic injection followed by a splenectomy, the majority of these clones are able to generate hepatic metastases, but with different frequencies of colonization and varying growth rates. Using the In Vivo Imaging System (IVIS), it is possible to visualize and quantify metastasis development with in vivo luminescent and ex vivo fluorescent imaging. In addition, Diffuse Luminescent Imaging Tomography (DLIT) provides a 3D distribution of liver metastases in vivo. Ex vivo fluorescent imaging of harvested livers provides quantitative measurements of individual hepatic metastatic colonies, allowing for the evaluation of the frequency of liver colonization and the growth kinetics of metastases. Since the model is similar to clinically observed liver metastases, it can serve as a modality for detecting genes associated with liver metastasis and for testing potential ablative or adjuvant treatments for liver metastatic disease.

Pulmonary Resection for Synchronous M1b-cStage IV Non-Small Cell Lung Cancer Patients

BACKGROUND

We wanted to assess the efficacy of curative intent pulmonary resection for non-small cell lung cancer (NSCLC) patients with synchronous M1b-distant metastases in a single organ or lesion.

METHODS

Between 1995 and 2015, 23 consecutive synchronous M1b-cStage IV NSCLC patients who underwent any treatment for metastases and curative intent pulmonary resection were retrospectively analyzed.

RESULTS

Sixteen patients were men and 7 were women, with a median age of 56 years (range: 41 to 76 years). There were 17 adenocarcinoma, 4 large-cell carcinoma, 1 large-cell neuroendocrine cancer, and 1 carcinosarcoma. Thirteen patients had no lymph node metastasis. Fourteen patients received preoperative chemotherapy, and 10 received postoperative chemotherapy. The metastatic sites were the brain in 13 patients; bone in 3 patients; adrenal glands and extrathoracic lymph nodes in 2 patients each; and the liver, small intestine, and subcutaneous tissue in 1 patient each. Nineteen patients underwent lobectomy, and the other 4 patients underwent pneumonectomy. Seventeen patients experienced recurrence as follows: local recurrence in 3 patients, distant recurrence in 13 patients, and both in 1 patient. The 5-year progression-free survival rates in the 23 patients was14.5% (95% confidence interval: 0% to 30.6%), and the 5-year overall survival rate was 41.7% (95% confidence interval: 19.6% to 63.8%).

CONCLUSIONS

Some M1b-cStage IV NSCLC patients achieved longer survival than others with the same stage disease by using local treatment for distant metastases and curative intent pulmonary resection. Oligometastatic patients might have been inadvertently included in the present cohort. However, at present, the optimum method for patient selection remains unclear.

Surgery in oligometastatic NSCLC patients in the targeted therapy era

More than 50% of NSCLC patients present with metastatic disease at first diagnosis, with a median survival of 8-11 months. However, selected patients with oligometastatic disease who receive appropriate local therapy for both the primary lesion and metastases enjoy long-term survival or are even cured. The new (eighth) edition of the tumor, node and metastasis classification of lung cancer suggests that patients with a single metastatic lesion in one distant organ should be placed into a new category, M1b, which will certainly lead to more applications of local therapy in such subpopulations. Moreover, as the applications of targeted therapy increase, surgery will play an evermore critical role in eliminating drug-resistant cancer clones of patients who exhibit mixed responses to tyrosine kinase inhibitors. The lung, brain and adrenal gland are the most common oligometastatic organs, and are reviewed separately.

The impact of local treatment of the primary tumor site in node positive and metastatic prostate cancer patients

BACKGROUND

Surgical treatment of the primary tumor in patients with metastatic prostate cancer (mPCa) is gaining traction. We discuss the biological rational and the existing literature on this approach.

METHODS

We reviewed the literature regarding surgical management of advanced and mPCa disease.

RESULTS

Surgical removal of the primary tumor despite metastases is becoming a standard in an increasing number of malignancies. Basic science data support the use of surgical removal of the prostate in metastatic PCa. In addition, durable long-term survival has been reported in patients with node-positive PCa treated with radical prostatectomy (RP) as mono or multimodal approach. Based on these data, several groups have demonstrated the feasibility and safety of RP in the metastatic setting. Retrospective series have also reported an improvement in survival for metastatic patients treated with RP in addition to systemic treatment.

CONCLUSIONS

Although no level I data exist at this time to support the use of RP in clinically node-positive or mPCa patients, retrospective data together with basic research data and experience from other malignancies suggest that treatment of the primary tumor, in form of a RP, is safe and could improve long-term quality of life and survival. However, prospective evaluations are requested to validate these findings before including in the standard clinical practice.

Role of Local Ablative Therapy in Patients with Oligometastatic and Oligoprogressive Non-Small Cell Lung Cancer

Because of an improved understanding of lung cancer biology and improvement in systemic treatment, an oligometastatic state in which metastatic disease is present at a limited number of anatomic sites is being increasingly recognized. An oligoprogressive state, which is a similar but distinct entity, refers to disease progression at a limited number of anatomic sites, with continued response or stable disease at other sites of disease. Such an oligoprogressive state is best described in patients with NSCLC treated with molecular targeted therapy. Possible explanations for development of the oligoprogressive state include the presence of underlying clonal heterogeneity and extrinsic selection pressure due to the use of targeted therapy. Traditionally, local ablative therapy (LAT) has been limited to symptom palliation in patients with advanced NSCLC, but the presence of oligometastatic or oligoprogressive disease provides a unique opportunity to evaluate the role of LAT such as surgery, radiation therapy, radiofrequency ablation, or cryoablation. There is increasing evidence to support the clinical benefit of LAT in patients with NSCLC with limited metastatic disease and in selected individuals in whom resistance to targeted therapies develops. In the latter instance, adequate treatment of drug-resistant clones by LAT could potentially help in avoiding switching systemic therapy prematurely. This review focuses on the biology of oligometastatic and oligoprogressive NSCLC and describes the role of LAT in the treatment of these conditions.

Pulmonary metastasectomy - A retrospective comparison of surgical outcomes after laser-assisted and conventional resection

INTRODUCTION

Indications and surgical techniques for pulmonary metastasectomy (PME) are controversially discussed issues. Laser-assisted surgery (LAS) is a recent innovation that has been advocated especially in patients with multiple pulmonary metastases (PM). However, there are hardly any studies comparing surgical outcomes after laser-assisted and conventional resection. The aim of the current study was to evaluate the value of LAS in a larger study population.

MATERIALS & METHODS

A retrospective analysis was completed on 178 consecutive patients undergoing 236 PMEs at a single center between 2010 and 2015. The main endpoint was survival. Statistical analysis was performed using the Kaplan-Meier method and survival rates were compared with the log rank test. Follow-up was done with special attention to the development of recurrent PM. Local relapse was defined as a recurrent metastasis in direct relation to the previously resected area according to CT scan comparisons.

RESULTS

LAS was performed on 256 metastases in 99 patients, non-laser-assisted surgery (NLAS) on 127 metastases in 79 patients. 5-year-survival rates were 69.3% in all patients, 65.7% after LAS and 73.6% after NLAS. There was no statistically significant survival difference after LAS or NLAS (p = 0.41). The rate of local relapse was 0.8% after LAS vs 3.1% after NLAS (p = 0.073).

CONCLUSION

Despite a larger number of negative predictors for survival in LAS patients, overall survival (OS) was similar in the compared groups. There was also a trend for a lower risk of local relapses after LAS. Therefore, LAS should be considered a promising method for PME.

New Strategies in Stereotactic Radiotherapy for Oligometastases

Patients with metastatic solid tumors are usually treated with palliative intent. Systemic therapy and palliative radiation are often used, with the goals of prolonging survival or maintaining quality of life, but not of cure. In contrast to this paradigm, the theory of oligometastasis suggests that some patients who have a small number of metastases may be amenable to cure if all lesions can be eradicated. Aggressive treatment of patients with oligometastases, using either surgery or radiotherapy, has become more common in the past decade, yet in most situations, no randomized evidence is available to support such an approach. Stereotactic ablative radiotherapy (SABR) is a novel treatment for oligometastases, delivering large doses of radiotherapy in only a few treatments, with excellent rates of local control, and appears to be an excellent noninvasive alternative to surgical resection of metastases. This article reviews recent biologic and clinical data that support the existence of the oligometastatic state and discusses gaps in this evidence base. The emerging role for SABR in the management of this challenging patient population is discussed with a focus on ongoing clinical trials in an attempt to improve overall survival, delay progression, or induce immunologic anticancer effects through the abscopal effect.

Imaging oligometastatic cancer before local treatment

With the advent of novel treatment strategies to help widen the therapeutic window for patients with oligometastatic cancer, improved biomarkers are needed to reliably define patients who can benefit from these treatments. Multimodal imaging is one such option and should be optimised to comprehensively assess metastatic sites, disease burden, and response to neoadjuvant treatment in each disease setting. These features will probably remain important prognostic biomarkers, and are crucial in planning multidisciplinary treatment. There are opportunities to extract additional phenotypic information from conventional imaging, while novel imaging techniques can also reveal specific aspects of tumour biology. Imaging can both characterise and localise the phenotypic heterogeneity of multiple tumour sites. Novel approaches to existing imaging datasets and correlation with tumour biology will be important in realising the potential of imaging to guide treatment in the oligometastatic setting. In this Personal View, we discuss the current status and future directions of imaging before treatment in patients with extracranial oligometastases.

Clinical applications of stereotactic radiation therapy for oligometastatic cancer patients: a disease-oriented approach

Oligometastases from solid tumors are currently recognized as a distinct clinical entity, corresponding to an intermediate state between local and widespread disease. It has been suggested that local ablative therapies (including surgery, radiofrequency ablation and radiation therapy) play an important role in this setting, in combination or not with systemic therapies, particularly in delaying disease progression and hopefully in increasing the median survival time. Stereotactic body radiation therapy (SBRT) rapidly emerged in recent years as one of the most effective and less toxic local treatment modalities for lung, liver, adrenal, brain and bone metastases. The aim of this review was to focus on its clinical role for oligometastatic disease in four major cancer subtypes: lung, breast, colorectal and prostate. On the basis of the available evidence, SBRT is able to provide high rates of local tumor control without significant toxicity. Its global impact on survival is uncertain; however, in specific subpopulations of oligometastatic patients there is a trend towards a significant improvement in progression-free and overall survival rates; these important data might be used as a platform for clinical decision-making and establish the basis for the current and future prospective trials investigating its role with or without systemic treatments.

Oligometastatic prostate cancer: Metastases-directed therapy?

Since the introduction of anatomical and functional imaging with multiparametric magnetic resonance imaging and choline or prostate-specific membrane antigen positron emission tomography-computed tomography, we are able to diagnose a previously unknown disease, the oligometastatic prostate cancer after local therapy. Reports on surgical and radiation treatment for low-volume metastatic recurrence have shown promising results, with definitive cure in few but a relevant delay of androgen-deprivation therapy with both treatment methods. Obviously, these results need to be validated with prospective randomised data.

Ablative Approaches for Pulmonary Metastases

Pulmonary metastases are common in patients with cancer for which surgery is considered a standard approach in appropriately selected patients. A number of patients are not candidates for surgery due to a medical comorbidities or the extent of surgery required. For these patients, noninvasive or minimally invasive approaches to ablate pulmonary metastases are potential treatment strategies. This article summarizes the rationale and outcomes for non-surgical treatment approaches, including radiotherapy, radiofrequency and microwave ablation, for pulmonary metastases.

Radiation Therapy for Oligometastatic Non-Small Cell Lung Cancer: Theory and Practice

Management paradigms for metastatic non-small cell lung cancer (mNSCLC) are evolving. Locally ablative therapies are now being increasingly integrated into combined-modality treatment strategies for mNSCLC patients with limited burdens of metastatic foci, termed oligometastases. Concurrently, techniques allowing for precise high-dose radiotherapy delivered over 1 to 5 total treatments, termed stereotactic body radiation therapy (SBRT) or stereotactic ablative radiation therapy (SABR), have emerged as a powerful means of noninvasive tumor ablation with broad patient candidacy. Strong rationale exists for ablative therapy in the setting of oligometastatic NSCLC, including patterns-of-failure analyses and data supporting local ablation of oligoprogressive disease for patients with oncogene-addicted mNSCLC treated with tyrosine kinase inhibitors. In this article, we examine the theoretical basis for ablation of oligometastatic NSCLC and review the growing clinical literature of mNSCLC patients treated with ablative radiation therapy.

Clinical and molecular markers of long-term survival after oligometastasis-directed stereotactic body radiotherapy (SBRT)

BACKGROUND

The selection of patients for oligometastasis-directed ablative therapy remains a challenge. The authors report on clinical and molecular predictors of survival from a stereotactic body radiotherapy (SBRT) dose-escalation trial for oligometastases.

METHODS

Patients who had from 1 to 5 metastases, a life expectancy of >3 months, and a Karnofsky performance status of >60 received escalating SBRT doses to all known cancer sites. Time to progression, progression-free survival, and overall survival (OS) were calculated at the completion of SBRT, and clinical predictors of OS were modeled. Primary tumor microRNA expression was analyzed to identify molecular predictors of OS.

RESULTS

Sixty-one evaluable patients were enrolled from 2004 to 2009. The median follow-up was 2.3 years for all patients (range, 0.2-9.3 years) and 6.8 years for survivors (range, 2.0-9.3 years). The median, 2-year, and 5-year estimated OS were 2.4 years, 57%, and 32%, respectively. The rate of progression after SBRT was associated with an increased risk of death (hazard ratio [HR], 1.44; 95% confidence interval [CI], 1.24-1.82). The time from initial cancer diagnosis to metastasis (HR, 0.98; 95% CI, 0.98-0.99), the time from metastasis to SBRT (HR, 0.98; 95% CI, 0.98-0.99), and breast cancer histology (HR, 0.12; 95% CI, 0.07-0.37) were significant predictors of OS. In an exploratory analysis, a candidate classifier using expression levels of 3 microRNAs (miR-23b, miR-449a, and miR-449b) predicted survival among 17 patients who had primary tumor microRNA expression data available.

CONCLUSIONS

A subset of oligometastatic patients achieves long-term survival after metastasis-directed SBRT. Clinical features and primary tumor microRNA expression profiling, if validated in an independent dataset, may help select oligometastatic patients most likely to benefit from metastasis-directed therapy. Cancer 2016;122:2242-50. © 2016 American Cancer Society.

Approach for oligometastasis in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) harboring a limited number of distant metastases, referred to as the oligometastatic state, has been indicated for surgery for the past several decades. However, whether the strategy of surgical treatment results in a survival benefit for such patients remains controversial. Experientially, however, thoracic surgeons often encounter long-term survivors among surgically resected oligometastatic NSCLC patients. In this article, the current situation of surgical approach and potential future perspective for oligometastatic NSCLC are reviewed.

Exosomal miRNAs as biomarkers of recurrent lung cancer

Prognosis of lung cancer still remains grim largely due to recurrence and aggressive metastasis of the disease. In this study, we examined the potential of exosomal miRNAs as biomarkers of recurrent lung cancer. Initially, in vitro miRNA profiles of normal lung (Beas-2b) and lung cancer (H1299) cells and of exosomes isolated from conditioned media were determined. In vivo study involved establishing subcutaneous primary and recurrent lung cancer xenografts in nude mouse model and examining tumor and serum exosomal miRNA alteration in secondary/recurrent lung tumors. A total of 77 miRNAs were observed to be significantly modulated in the H1299 cells (47 miRNA upregulated and 30 downregulated) compared to the Beas-2b cells. The exosomes isolated from conditioned media indicated several miRNAs which were in agreement with cells of origin. A similarity was also observed between miRNAs from serum exosomes and tumors, indicating their origin from the lung tumors. Two miRNAs, miR-21 and miR-155, were found to be significantly upregulated in recurrent tumors compared to primary tumors. These miRNAs were also upregulated in serum exosomes of recurrent tumor-bearing animals versus non-tumor- or primary tumor-bearing animals. Increased expression of the recurrent disease markers were also observed in recurrent tumors compared with primary tumors. Serum exosomes from recurrent tumor mice mirrored its tumor profile in expressing higher levels of these proteins compared with exosomes from primary tumor mice. Our data suggest that exosomal miRNA signatures may be a true representation of a pathological profile of lung cancer; thus, miRNAs could serve as promising biomarkers for non-invasive diagnosis of the disease.

Is Surgery Warranted for Oligometastatic Disease?

The development of metastases after curative treatment can be seen as a failure. A common justification for the removal of metastases is that the knowledge that they are there may cause psychological distress, a real symptom that may be relieved by their removal. Although it is a commonly used justification for metastasectomy, the authors are unaware of any studies confirming or quantifying the health gain. This article strongly challenges the belief in clinical effectiveness and demonstrates that it is supported neither by a sound biological rationale nor by any good evidence. Reasons are suggested why this unfounded belief has become so prevalent.

14q32-encoded microRNAs mediate an oligometastatic phenotype

Oligometastasis is a clinically distinct subset of metastasis characterized by a limited number of metastases potentially curable with localized therapies. We analyzed pathways targeted by microRNAs over-expressed in clinical oligometastasis samples and identified suppression of cellular adhesion, invasion, and motility pathways in association with the oligometastatic phenotype. We identified miR-127-5p, miR-544a, and miR-655-3p encoded in the 14q32 microRNA cluster as co-regulators of multiple metastatic pathways through repression of shared target genes. These microRNAs suppressed cellular adhesion and invasion and inhibited metastasis development in an animal model of breast cancer lung colonization. Target genes, including TGFBR2 and ROCK2, were key mediators of these effects. Understanding the role of microRNAs expressed in oligometastases may lead to improved identification of and interventions for patients with curable metastatic disease, as well as an improved understanding of the molecular basis of this unique clinical entity.

Multi-reoperations for lung metastases

In this study, we investigated role and results of multi-reoperations for lung metastases. From 1986 to 2010, 113 consecutive patients (61 men and 52 women; mean age: 53.2 ± 12.8 years) underwent repeated lung metastasectomy with curative intent in our institution. Two procedures were performed in 113 patients, three in 54, four in 31, five in eight and six in three. There was no perioperative mortality. Cumulative 5-year survival was 65% and this was significantly higher than the value recorded for patients undergoing only one metastasectomy (42%; p = 0.021). Size, number of resections and probability of recurrence increased by number of operation whereas disease free interval reduced. At any metastasectomy both short disease-free interval and multiple metastases resulted in the most significant negative prognosticators. In conclusion, redo metastasectomy is worthwhile for the initial procedures, afterwards both disease-free and overall survivals decrease and surgery lose its efficacy.

Stereotactic ablative radiotherapy for pulmonary oligometastases and oligometastatic lung cancer

An increasing body of experience suggests that oligometastasis represents a minimal metastatic state with the potential for cure or prolonged survival in selected patients treated with radical local therapy to all identified sites of disease. The main clinical scenarios managed by thoracic oncology specialists are pulmonary oligometastases from primary malignancies of other anatomic sites and primary lung cancer with oligometastases to lung or other organs. Surgery has been a mainstay of treatment in these situations, with remarkably favorable outcomes following pulmonary metastasectomy in well-selected patient cohorts. As with early stage lung cancer in patients who are medically inoperable, stereotactic ablative radiotherapy is emerging as a prominent local treatment option for oligometastatic disease. We review the role and clinical experience of stereotactic ablative radiotherapy for pulmonary oligometastases and oligometastatic lung cancer.

Extending the Frontiers Beyond Thermal Ablation by Radiofrequency Ablation: SBRT, Brachytherapy, SIRT (Radioembolization)

Metastatic spread of the primary is still defined as the systemic stage of disease in treatment guidelines for various solid tumors. This definition is the rationale for systemic therapy. Interestingly and despite the concept of systemic involvement, surgical resection as a local treatment has proven to yield long-term outcomes in a subset of patients with limited metastatic disease, supporting the concept of oligometastatic disease. Radiofrequency ablation has yielded favorable outcomes in patients with hepatocellular carcinoma and colorectal metastases, and some studies indicate its prognostic potential in combined treatments with systemic therapies. However, some significant technical limitations apply, such as size limitation, heat sink effects, and unpredictable heat distribution to adjacent risk structures. Interventional and non-invasive radiotherapeutic techniques may overcome these limitations, expanding the options for oligometastatic patients and cytoreductive concepts. Current data suggest very high local control rates even in large tumors at any given location in the human body. The article focusses on the characteristics and possibilities of stereotactic body radiation therapy, interstitial high-dose-rate brachytherapy, and Yttrium-90 radioembolization. In this article, we discuss the differences of the technical preferences as well as their impact on indications. Current data is presented and discussed with a focus on application in oligometastatic or cytoreductive concepts in different tumor biologies.

Oligometastatic disease, the curative challenge in radiation oncology

The concept of oligometastatic disease was first described by Hellman and Weichselbaum in 1995. The mere insight of this concept led to the hypothesis that this disease may be cured using local ablative weapons. Surgery has already demonstrated this hypothesis. Surgery limitations, either technical or due to refusal or associated comorbidity, have led to implement alternative ablative options such as stereotactic body radiation therapy (SBRT). SBRT evolved from (stereotactic radiosurgery) because of the need to irradiate extracranial lesions and has been shown to be safe and effective. SBRT achieves local control rates ranging from 70%-90%, but highly variable survival rates depending on the group analyzed. Series with heterogeneous metastatic sites and tumor origin have reported 20% survival rates at 2-3 years, similar to those achieved with surgery. Despite its excellent results, SBRT still faces significant clinical challenges. Its optimal integration with systemic treatment is unknown, and response assessment is very difficult. However, the greatest challenge lies in selection of patients most likely to remain oligometastatic, those who will most benefit from the technique. Biomarkers, molecular signatures, that accurately predict the biological behavior of malignancy are needed. The expression profile of specific miRNAs has been shown to have a potential in this regard.

Imaging of tumor clones with differential liver colonization

We present a model of hepatic colorectal metastases which represents monoclonal cell lines double-labeled by luciferase and tdTomato. These cells form liver metastasis in varying numbers and patterns similar to those observed in patients. Using in vivo and ex vivo luminescent and fluorescent imaging we determine the growth kinetics and clonogenic frequency of tumor cells colonizing liver. Molecular profiling detected stable expressional differences between clones consistent with their phenotypes. The data indicate that clinically relevant phenotypes of liver metastases can be modeled in vivo.

The biology and treatment of oligometastatic cancer

Clinical reports of limited and treatable cancer metastases, a disease state that exists in a transitional zone between localized and widespread systemic disease, were noted on occasion historically and are now termed oligometastasis. The ramification of a diagnosis of oligometastasis is a change in treatment paradigm, i.e. if the primary cancer site (if still present) is controlled, or resected, and the metastatic sites are ablated (surgically or with radiation), a prolonged disease-free interval, and perhaps even cure, may be achieved. Contemporary molecular diagnostics are edging closer to being able to determine where an individual metastatic deposit is within the continuum of malignancy. Preclinical models are on the outset of laying the groundwork for understanding the oligometastatic state. Meanwhile, in the clinic, patients are increasingly being designated as having oligometastatic disease and being treated owing to improved diagnostic imaging, novel treatment options with the potential to provide either direct or bridging therapy, and progressively broad definitions of oligometastasis.

Surgery or ablative radiotherapy for breast cancer oligometastases

Precisely focused radiation or surgical resection of limited metastases resulted in long-term disease control and survival in multiple studies of patients with oligometastatic breast cancer. The integration of these ablative techniques into standard systemic therapy regimens has the potential to be paradigm shifting, leaving many patients without evidence of disease. Although an attractive treatment option, the utility of these therapies have not been proven in controlled studies, and improved outcomes may be because of patient selection or favorable biology alone. Ongoing studies continue to refine radiation techniques and determine the role for ablative therapies in the management of patients with metastatic breast cancer (MBC). Additionally, patient selection for metastasis-directed therapies is based on clinical criteria, with many not benefiting from therapies that may have substantial toxicities. Recent reports are beginning to uncover the biology of oligometastatic cancer, but much work is needed. Current and developing trials that integrate both clinical and translational endpoints have the potential to transform management strategies in women with limited MBC.

Oligometastases in prostate cancer: restaging stage IV cancers and new radiotherapy options

There are various subgroups of patients with metastatic prostate cancer: polymetastatic, oligometastatic, or oligo-recurrent cancers whose progression follows different courses and for whom there are different treatment options. Knowledge of tumor dissemination pathways and different genetic and epigenetic tumor profiles, as well as their evolution during disease progression, along with new diagnostic and therapeutic advances has allowed us to address these situations with local ablative treatments such as stereotactic body radiation therapy or stereotactic radiosurgery. These treatments provide high rates of local control with low toxicity in metastatic spread for primary cancers including those of pulmonary, digestive, and renal origin, while these types of treatments are still emerging for cancers of prostatic origin. There are several retrospective studies showing the effectiveness of such treatments in prostate cancer metastases, which has led to the emergence of prospective studies on the issue and even some phase II studies intended to prevent or delay systemic treatments such as chemotherapy. Here we collect together and review these past experiences and the studies currently underway. These types of radiotherapy treatments redefine how we approach extracranial metastatic disease and open up new possibilities for combination therapy with new systemic treatment agents.

Oligometastasis and oligo-recurrence: more than a mirage

The standard treatment choice for cancer metastasis has been systemic management, including cytotoxic chemotherapy, hormonal manipulation, and targeted therapy. Emerging evidence has shown an oligometastatic state, an intermediate state between limited primary cancer and polymetastatic cancer, in which local therapy for metastatic lesions results in satisfactory survival comparable to non-metastatic disease. We provide a comprehensive introduction of evidence from experimental and clinical studies in favor of the oligometastatic phenotype, we review the efficacy and safety of surgery and stereotactic body radiotherapy in the treatment of oligometastases, and finally, we discuss the way to differentiate the oligometastatic state from polymetastasis.

History and present status of pulmonary metastasectomy in colorectal cancer

Clinical practice with respect to metastatic colorectal cancer differs from the other two most common cancers, breast and lung, in that routine surveillance is recommended with the specific intent of detecting liver and lung metastases and undertaking liver and lung resections for their removal. We trace the history of this approach to colorectal cancer by reviewing evidence for effectiveness from the 1950s to the present day. Our sources included published citation network analyses, the documented proposal for randomised trials, large systematic reviews, and meta-analysis of observational studies. The present consensus position has been adopted on the basis of a large number of observational studies but the randomised trials proposed in the 1980s and 1990s were either not done, or having been done, were not reported. Clinical opinion is the mainstay of current practice but in the absence of randomised trials there remains a possibility of selection bias. Randomised controlled trials (RCTs) are now routine before adoption of a new practice but RCTs are harder to run in evaluation of already established practice. One such trial is recruiting and shows that controlled trial are possible.

The role of surgery and ablative radiotherapy in oligometastatic breast cancer

The ability to deliver precise focused radiation, combined with improved surgical techniques, has led to multiple reports of long-term survivors in patients with oligometastatic breast cancer. The removal or ablation of known metastases, often present after systemic therapy regimens has the potential to be paradigm shifting rendering many patients without evidence of disease. However, the utility of these therapies has not been proven in phase III studies. Additionally, patient selection for metastasis-directed therapies is based on clinical criteria, with many patients not benefiting from these therapies. Refinements of radiation techniques are continuing, and discoveries are uncovering the biology of breast cancer in the oligometastatic state among patients. Integrated into ongoing studies, and those in development, they have the potential to alter standard management strategies in oligometastatic patients.

Clinical cancer research: the past, present and the future

In the past decade, we have witnessed unprecedented changes and some remarkable advances that have enabled true personalized medicine. Nevertheless, many challenges in clinical cancer research remain and need to be overcome if we are to witness similar progress in the next decade. Such hurdles include, but are not limited to, clinical development and testing of multiple agents in combination, design of clinical trials to best accommodate the ever increasing knowledge of heterogeneity of the disease, regulatory challenges relating to drug development and trial design, and funding for basic research. With this in mind, we asked four leading cancer researchers from around the world, and who have been associated with the journal since its launch in November 2004 what, in their opinion, we have learnt over the past 10 years and how we should progress in the next 10 years.

Radical irradiation of extracranial oligometastases

Advances in radiotherapy planning and delivery have been used to treat patients with limited metastatic disease. With these techniques, high rates of treated metastasis control and low toxicity have been reported. Some patients have long disease-free intervals after radiotherapy similar to those seen after surgical resection. Ongoing studies will determine the benefit of these irradiation techniques to treat limited metastases, identify appropriate candidates, and assist in integrating these treatments into management strategies for specific diseases.

Local ablative treatments of oligometastases from head and neck carcinomas

BACKGROUND

Median survival for recurrent/metastatic (unknown poly/oligometastatic status) head and neck cancer patients (HNSCC) is ten months with best systemic treatment. Metastatic ablation shows promising results in selected patients with several tumor types. We aimed to assess the role of surgery and stereotactic ablative body radiotherapy (SABR) with respect to survival in HNSCC.

MATERIALS AND METHODS

Published data on metastatic HNSCC treated ablatively were analyzed.

RESULTS

Five-year survival rates after pulmonary/liver metastasectomy exceed 20% in selected patients. Two-year survival after lung SABRT of metastasectomy yields 35%. Interesting data on survival and tolerance are reported in other metastatic sites.

CONCLUSION

Surgery yields the best level of evidence. However, non-invasive SABR is efficient and well-tolerated in lung/liver, bone and other metastatic locations. Systemic treatment may be given sequentially with ablative treatments, or omitted in well-identified situations. Proper patient selection for local ablative treatment and optimal therapeutic sequence should be assessed in randomized trials.