Table 1 Risk of bias assessment using NOS
| No. | Name of the study | Journal | Quality Score |
|---|---|---|---|
| 1 | Identifying Patients at Risk of Early Postoperative Recurrence of Lung Cancer: A New Use of the Old CEA Test | Ann Thorac Surg | Good |
| 2 | Predictive factors for node metastasis in patients with clinical stage I non-small cell lung cancer | Annals of Thoracic Surgery | Poor |
| 3 |
Risk Factors for Predicting Occult Lymph Node Metastasis in Patients with Clinical Stage I Non-small Cell Lung Cancer Staged by Integrated Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography | World Journal of Surgery | Good |
| 4 | Optimal Predictive Value of Preoperative Serum Carcinoembryonic Antigen for Surgical Outcomes in Stage I Non-Small Cell Lung Cancer: Differences According to Histology and Smoking Status | Journal of Surgical Oncology | Fair |
| 5 | Clinical significance of preoperative carcinoembryonic antigen level for clinical stage I non-small cell lung cancer: can preoperative carcinoembryonic antigen level predict pathological stage? | Interactive CardioVascular and Thoracic Surgery | Good |
| 6 |
Predictive Risk Factors for Mediastinal Lymph Node Metastasis in Clinical Stage IA Non–Small-Cell Lung Cancer Patients | Journal of Thoracic Oncology: Official Publication of the International Association for the Study of Lung Cancer | Fair |
| 7 |
Sialyl Lewis X as a predictor of skip N2 metastasis in clinical stage IA non-small cell lung cancer | World Journal of Surgical Oncology | Good |
| 8 | Clinical significance of preoperative carcinoembryonic antigen level in patients with clinical stage IA non-small cell lung cancer | J Thorac Dis | Good |
| 9 | Prognostic impact of Cyfra21–1 and other serum markers in completely resected non-small cell lung cancer | Lung Cancer | Good |
| 10 | Significant correlation between urinary N1, N12-diacetylspermine and tumor invasiveness in patients with clinical stage IA non-small cell lung cancer | BMC Cancer | Poor |
| 11 |
Prediction of lymph node status in clinical stage IA squamous cell carcinoma of the lung | European Journal of Cardio-Thoracic Surgery | Good |
| 12 |
Predictive Factors for Lymph Node Metastasis in Clinical Stage IA Lung Adenocarcinoma | Annals of Thoracic Surgery | Poor |