Forty years on: pulmonary metastasectomy for sarcoma

Improving survival after pulmonary metastasectomy for sarcoma: analysis of prognostic factors

BACKGROUND

Metastatic sarcoma confers a grave prognosis to patients and poses a management dilemma for clinicians. Pulmonary metastasectomy is frequently performed for the recurrence of sarcomatous tumours in the lung, but the evidence-base is poor. No guidelines exist to inform clinicians on appropriate patient selection and surgical technique.

AIM

This review aims to establish and analyse the most important prognostic factors for survival post pulmonary metastasectomy for recurrent sarcoma. We summarise the key tumour, peri-operative and patient characteristics that should guide surgical management.

METHODS

A comprehensive search of the literature utilising OVID Medline and PubMed databases was conducted to identify all relevant research within the past 15 years. We evaluated all articles that specifically studied sarcoma patients (both bone and soft tissue).

CONCLUSION

Disease-free interval and tumour burden remain important prognostic factors, while tumour grade is likely not significant. VATS is a safe and viable alternative to thoracotomy without sacrificing survival outcomes. No single peri-operative characteristic provides useful prognostic information in isolation.

The oligometastatic spectrum in the era of improved detection and modern systemic therapy

Metastases remain the leading cause of cancer-related mortality. The oligometastasis hypothesis postulates that a spectrum of metastatic spread exists and that some patients with a limited burden of metastases can be cured with ablative therapy. Over the past decade, substantial advances in systemic therapies have resulted in considerable improvements in the outcomes of patients with metastatic cancers, warranting re-examination of the oligometastatic paradigm and the role of local ablative therapies within the context of the improved therapeutic responses, shifting patterns of disease recurrence and possible synergy with systemic treatments. Herein, we reframe the oligometastatic phenotype as a dynamic state for which locally ablative, metastasis-directed therapy improves clinical outcomes, including by prolonging survival and increasing cure rates. Important risk factors defining the metastatic spectrum are highlighted that inform both staging and therapy. Finally, we synthesize the literature on combining local therapies with modern systemic treatments, identifying general themes to optimally integrate ablative therapies in this context.

Pulmonary metastasectomy: limits to credibility

Lung metastases are a common site of spread for many malignant tumours. Pulmonary metastasectomy has been practiced for many years for sarcomas and is now becoming increasingly frequently advocated for patients with many other tumours, especially colorectal cancer. In this article we argue that this procedure is one framed by therapeutic opportunity and not supported by strong evidence. It is potentially harmful and may not be effective. Our argument is based on several important issues: (I) the vagueness of the concept of "oligometastases" and its biological implausibility; (II) the flaws in the often-cited observational evidence, especially selection bias; (III) the lack of any reliable randomised trial evidence of improved survival but evidence of harm; (IV) the failure of strategies to detect metastases earlier to influence overall survival. The introduction of stereotactic radiotherapy and image-guided thermal ablation have made the urge to treat lung metastases stronger but without any good evidence to justify their use. We acknowledge the problems of carrying out randomised trials when there is a clear lack of equipoise in the clinical teams involved but believe that there is an ethical need to do so. Many patients are probably being given false hope of cure or prolonged survival but are at risk of harm from pulmonary metastasectomy or ablation. It is possible that a few patients may benefit but without better evidence we do not know which, if any, do.

Randomised Controlled Trial Evidence Questions the Assumption that Pulmonary Metastasectomy Benefits Patients with Colorectal Cancer

Pulmonary metastasectomy for sarcoma is surgery without proven benefit, and in the light of a randomized controlled trial examining pulmonary metastasectomy in colorectal cancer, it should be questioned.

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.

The role of stereotactic body radiation therapy in the management of oligometastatic lung cancer

A growing body of evidence has surfaced over the past 20 years that supports the use of surgery for metastasis limited in number termed ‘oligometastases’. Local therapy for oligometastases results in long progression free survival in the absence of systemic therapy, including non-small-cell lung cancer (NSCLC). Stereotactic body radiation therapy (SBRT) allows for the delivery of anatomically precise, ablative doses of radiation therapy able to achieve local control rates of approximately 80% with minimal toxicity. In NSCLC, SBRT is emerging as an effective therapy in the management of sites resistant to targeted therapy. This review summarizes the published evidence for the use of local therapy in the management of oligometsatic cancer, with a focus on SBRT and NSCLC.

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 oligometastatic state - separating truth from wishful thinking

The oligometastatic paradigm implies that patients who develop a small number of metastatic lesions might achieve long-term survival if all these lesions are ablated with surgery or stereotactic radiotherapy. Clinical data indicate that the number of patients with oligometastatic disease receiving aggressive treatment is increasing rapidly. We examine the key evidence supporting or refuting the existence of an oligometastatic state. Numerous single-arm studies suggest that long-term survival is 'better-than-expected' after ablative treatment. However, the few studies with adequate controls raise the possibility that this long-term survival might not be due to the treatments themselves, but rather to the selection of patients based on favourable inclusion criteria. Furthermore, ablative treatments carry a risk of harming healthy tissue, yet the risk-benefit ratio cannot be quantified if the benefits are unmeasured. If the strategy of treating oligometastases is to gain widespread acceptance as routine clinical practice, there should be stronger evidence supporting its efficacy.