Radiotherapy for primary tumor in lung cancer with synchronous metastases: Overview from the past and proposal for the future.

The management of metastatic lung cancers, either of the small-cell (SCLC) or the non-small cell (NSCLC) subtype, largely based on systemic treatments so far, has been the subject of breakthrough advances over the past few years, with notably the wide use of immunotherapy changing the landscape of these harmful prognosis diseases. In parallel with this major progress, the increasing use of radiotherapy (RT) for the treatment of the primary thoracic lesion±the distant lesions, may contribute to improving the condition of these metastatic patients, both in terms of progression-free survival (PFS) and overall survival (OS). This review proposes to summarize and explain the findings provided by the different studies published in the last years experiencing RT of the primary tumor in metastatic lung cancers, either associated or not with the local ablative treatment of a low number of distant lesions. It will also expose the respective limits encountered in these studies and, in the light of all these elements, suggests various promising issues and fields of research for the future.