Treatment outcome of patients with synchronous oligometastatic non-small cell lung cancer in the immunotherapy era: Analysis of a real-life intention-to-treat population

The standard first-line treatment for non-oncogene driven metastatic non-small cell lung cancer (NSCLC) is an immune checkpoint inhibitor (ICI) based strategy. Although guidelines increasingly advise adding local radical treatment (LRT) to patients with synchronous oligometastatic (sOMD) NSCLC responding to systemic therapy, this recommendation is based on the studies without ICI. Furthermore, the majority of published oligometastatic studies were not on an intention-to-treat basis, resulting in selection bias. Moreover, staging Positron Emission Tomography-Computed Tomography (PET-CT) and brain imaging were often not mandatory and definitions of oligometastatic were heterogeneous. Therefore, this study focused on a single centre retrospective series, including all adequately staged patients with sOMD NSCLC according to the European Organisation for Research and Treatment of Cancer definition (maximum of 5 metastases in 3 organs) that were treated with induction (chemo)-ICI and compared outcomes to those treated with chemotherapy only, with and without LRT. The primary end-points were median progression-free survival (PFS) and overall survival (OS) for patients treated with induction (chemo)-ICI versus chemotherapy. Out of 68 included patients, 38 (56%) eventually received LRT. With a median follow-up of 26.7 months, the median PFS was 19.0 months for (chemo)-ICI (n = 18) versus 6.8 for chemotherapy-only (n = 50) (HR 0.5, p = 0.03), the median OS was 19.3 versus 15.7 months, respectively (HR 0.8, p = 0.4). In patients having received LRT, median PFS was 19.0 months for (chemo)-ICI versus 8.3 for chemotherapy-only (HR 0.6, p = 0.2). In conclusion, an ICI-based systemic treatment is feasible and may result in superior survival outcomes. This should be investigated in prospective trials. Strategies to improve response rates to systemic treatment are also needed.