Cancer science
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Despite the importance of accurate disease definitions for effective management and treatment decisions, there is currently no consensus on what constitutes oligometastatic non-small-cell lung cancer (NSCLC). Predominant patterns of initial progressive disease (PD) after first-line systemic therapy have been shown to be a substantial basis for local ablative therapy (LAT) for all disease sites in patients with oligometastatic NSCLC, suggesting that these patterns could be helpful in defining synchronous oligometastatic NSCLC. Therefore, this retrospective study aimed to propose a threshold number of metastases for synchronous oligometastatic NSCLC, based on the pattern of initial PD after first-line systemic therapy. ⋯ The median survival times in patients with oligometastatic or non-oligometastatic NSCLC were 23.0 and 10.9 mo (hazard ratio, 0.51; P = .002), respectively. Based on these findings, we propose synchronous oligometastatic NSCLC as 1-3 metastases in accordance with patterns of initial progression. The result of our study might be contributory to provide a common definition of synchronous oligometastatic NSCLC.