Stage IV nonsmall cell lung cancer treatment: oligometastatic disease and disease progression, untangling the knot.

Stage IV nonsmall cell lung cancer (NSCLC) is a heterogeneous group of patients for whom systemic therapy is decided based on tumour-biological cancer features (histology, PD-L1 expression, genomic alteration, metastatic sites) and patient characteristics (performance status, comorbidities). In most instances, some kind of systemic treatment is proposed, for which immunotherapy-based or targeted therapies are considered the standards of care in 2024. Oligometastatic NSCLC represents a specific concept during the biological spectrum from localised to metastatic disease in which only a limited number of metastatic sites can be documented. Based on this assumption, prospective and a few randomised phase II studies have been performed, which suggested that adding a local ablative treatment to the systemic one can be a new option for selected stage IV NSCLC. The European Organisation for Research and Treatment of Cancer (EORTC) and the European Society for Radiotherapy and Oncology (ESTRO) supported efforts to define oligometastatic NSCLC to unify the semantics within the thoracic oncology community. This article summarises the currently available data and emphasises the questions and perspectives in oligometastatic disease NSCLC in European patient cohorts.