Table 1.

Comparison of Recent Definitions for Oligometastatic Non-Small Cell Lung Cancer in Clinical Trials, National Treatment Guidelines, and Consensus Definitions. Modern definitions for oligometastatic non-small cell lung cancer have varied widely.

Author	Year	Study Type	Maximum Number of Metastases	Maximum Number of Organ Sites	Maximum Lesions in Each Organ	Intrathoracic N+ as Metastasis	Pulmonary Lesion as Metastasis	Includes Intracranial Lesions	No Disease Progression after First Line Therapy	Notes
Ashworth [5]	2014	Meta-analysis	5	NS	NS	NS	Yes	Yes	NS
Gomez [2,3]	2016, 2019	RCT phase II	3	NS	NS	Yes	NS	Yes	Yes
Iyengar [27]	2018	RCT phase II	5	NS	3 in lung or liver	NS	Yes	Exclude uncontrolled intracranial	Yes
Palma [12,13]	2019, 2020	RCT phase II	5	NS	3	NS	NS	Exclude if only site of disease	Yes	Not lung cancer-specific
Dingemans [36] (EORTC-LCG)	2019	Consensus working group	5	3	NS	No	Yes	Yes	NS
TNM stage M1a [31]	2017	Staging Guidelines	1	1	1	No	Contralateral	Yes	NA
NCCN [34]	2021	Treatment Guidelines	3-5	NS	NS	No	Treat as second primary	Yes	NS
ESMO [35]	2018	Treatment Guidelines	3	NS	NS	NS	Treat as second primary	Yes	NS

Abbreviations. NS, not specified; RCT, randomized controlled trial; EORTC-LCG, The European Organization of Research and Treatment of Cancer—Lung Cancer Group; NCCN, National Comprehensive Cancer Network; ESMO, European Society for Medical Oncology.