What is oligo metastatic disease in lung cancer?

Prof. Anne-Marie C. Dingemans, MD PhD, Pulmonologist
Maastricht University Medical Center, Maastricht, The Netherlands Department of Pulmonology and GROW, School for Oncology and Development Biology

Long-term benefit of local ablative treatment (LAT( in patients with up to 3-5 metastatic sites was seen in several, mainly retrospective, series[1]. In the last years the concept of oligometastasic treatment evolved. The continuing interest was pushed by the increasing number of available treatment strategies, with widespread introduction of minimal invasive surgery and stereotactic radiotherapy. At ASCO 2016 the first randomized phase II trial was presented. Progression free survival (PFS), the primary endpoint, was shown to be significantly superior when oligometastatic NSCLC patients were treated with LAT compared to follow-up or maintenance therapy after treatment with at least four cycles of platinum containing chemotherapy or three months of EGFR-TKI (EGFR mutation) or crizotinib (ALK-rearrangement) [2]. The question arises whether we need additional evidence or whether the randomized phase II trial of Gomez with PFS as primary endpoint will change daily clinical practice. 

A search on clinical trial.gov learned that ongoing clinical trials all use different definitions of oligometastatic NSCLC and that they require different staging procedures. In order to speak the same language we need a uniform definition of oligometastatic NSCLC. The European Organisation of Treatment of Cancer (EORTC) lung cancer group started an initiative to come to a consensus definition of oligometastatic disease for synchronous NSCLC. 

References
1. Ashworth, A., et al., Is there an oligometastatic state in non-small cell lung cancer? A systematic review of the literature. Lung Cancer, 2013. 82(2): p. 197-203.
2. Gomez, D.R., et al., Local consolidative therapy versus maintenance therapy or observation for patients with oligometastatic non-small-cell lung cancer without progression after first-line systemic therapy: a multicentre, randomised, controlled, phase 2 study. Lancet Oncol, 2016. 17(12): p. 1672-1682.