The oligometastatic state—separating truth from wishful thinking

Abstract

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.

Is It Time for New Target Volumes in Radiation Oncology?

“…The authors did not detect a significant relationship between SBRT experience and overall survival, a relationship that had been demonstrated in a previous study in the setting of early-stage lung cancer (8). These disparate findings may be attributable to the fact that for oligometastases, whether SBRT influences overall survival at all is still a matter of open debate (15).…”

Oligometastatic Prostate Cancer: Is it Real ?

“…As the disease evolves, the chances are getting smaller and smaller and at some point, they disappear. The case of an intermediate clinical entity, potentially curable with local ablative techniques has been described by some as wishful thinking [8]. We do have though some supporting evidence that oligometastatic state represents a true intermediate biological state [9].…”

Surgery and ablative techniques for lung metastases in the Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) trial: is there equivalence?

“…There has been considerable recent interest in its use for lung metastases. The question was systematically reviewed and the authors pointed to the absence of evidence and raised the possibility that this was 'wishful thinking' (6). Despite the absence of evidence for any ablative techniques for metastases, SABR/SBRT has been much publicised for treatment of oligometastatic disease in the last year (19)(20)(21).…”