Unexpected long survival of brain oligometastatic non-small cell lung cancer (NSCLC) treated with multimodal treatment: a single-center experience and review of the literature

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Fifty percent of the cases are metastatic at diagnosis and about 20% develop brain metastasis. The brain involvement represents a negative prognostic factor. However, some patients could benefit from locoregional treatments of metastatic foci and experience an unexpected long survival or healing. In the previous years some classifications were proposed to identify patients' prognostic category, according to stage of the primary tumor, the timing of metastases occurrence (synchronous or metachronous) and the number of metastatic sites. Several data show a benefit in patients receiving resection of both the primary tumor and brain metastases. Whole brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS) are the selected options in most cases. Overall, literature data showed highly variable outcome, with an overall survival (OS) ranging from 5.9 to 68 months. No data from randomized and homogeneous trials are currently available. Therefore, a growing interest in this field is observed. Different trials investigating the effectiveness of local treatments and studies analyzing biological mechanisms are ongoing. In this report we analyze literature data and we explore the current field of study. Furthermore, we show a single institutional experience of multimodal management of stage IV NSCLC with brain metastases, experiencing an unexpected long survival. We conclude that a better knowledge of this subpopulation of patients and new studies in this field can lead to distinguish the patients who can benefit from local treatment from those with poor prognosis.