Table 1. Characteristics of the included studies.
| Study | Country | Tumor diameter | Pathology | Imaging features | Study design | Number of participants | Propensity score match | Covariates in PSM analysis | Multivariate analysis | Covariates in adjusted model | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Lob | Seg | ||||||||||
| Okada 2001 | Japan | ≤2 cm | NSCLC | Undefined | Retrospective cohort | 139 | 70 | No | – | No | – |
| Yamato 2008 | Japan | ≤2 cm | Adenocarcinoma | Undefined | Retrospective cohort | 277 | 153 | No | – | Yes | Age, sex, pT status, pN status, Noguchi classification |
| Zhong 2012 | China | ≤2 cm | NSCLC | Undefined | Retrospective cohort | 81 | 39 | No | – | Yes | Age, sex, tumor size, histology, location |
| Tsutani 2013 | Japan | ≤3 cm | Adenocarcinoma | Undefined | Retrospective cohort | 81 | 81 | Yes | Age, sex, sold tumor diameter, SUVmax, side, and lobe | No | – |
| Okada 2014 | Japan | ≤3 cm | Adenocarcinoma | Undefined | Retrospective cohort | 479 | 155 | No | – | Yes | Age, sex, tumor diameter, SUVmax |
| Jiang 2014 | China | ≤1 cm | NSCLC | Undefined | Retrospective cohort | 71 | 19 | No | – | Yes | Age, comorbidities, tumor diameter, serum CEA, pN status, differentiation, Visceral pleural involvement |
| Ogawa 2015 | Japan | 2–3 cm | NSCLC | Undefined | Retrospective cohort | 147 | 31 | No | - | No | - |
| Khullar 2015 | USA | ≤2 cm | NSCLC | Undefined | Retrospective cohort | 4857 | 286 | No | - | Yes | Age, sex, pathology, insurance, income, Charlson/Deyo score, differentiation, tumor diameter |
| Kodama 2016 | Japan | ≤2 cm | NSCLC | Non-GGN | Retrospective cohort | 232 | 80 | Yes | Age, sex, tumor diameter, CT feature, GGN ratio, preoperative diagnosis | Yes | CT feature, histology, lymphatic invasion, vascular invasion |
| Nishio 2016 | Japan | ≤2 cm | NSCLC | Undefined | Retrospective cohort | 72 | 118 | Yes | Age, sex, tumor diameter, GGN ratio, location | Yes | Age, tumor diameter, GGN ratio, location |
| Koike 2016 | Japan | ≤2 cm | NSCLC | Pure solid | Retrospective cohort | 151 | 100 | Yes | Age, sex, smoking status, percent predicted VC, FEV1/FVC, Serum CEA, tumor diameter, histology, lymphadenectomy extent, number of node examined | Yes | Age, smoking status, FEV1/FVC, serum CEA |
| Hattori 2017 | Japan | ≤2 cm | NSCLC | Non-GGN | Retrospective cohort | 270 | 83 | No | – | No | – |
Lob, lobectomy; Seg, segmentectomy; PSM, propensity score match; SUV, standard uptake volume; GGN, ground glass nodule; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; NSCLC, non-small cell lung cancer.