Table 1. Basic characteristics of included studies.
| Author | Year | Study period | Study design | Country | Sample size | Sex (F/M) | TNM stage | Treatment | Follow-up, median, [range] | Cut-off | Outcome | Source of HR | NOS score |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tong (14) | 2017 | 2006–2012 | Retrospective | China | 332 | 126/206 | III | Mixed | 22 [2–72] | 660 | OS | R | 8 |
| Gao (15) | 2018 | 2009–211 | Retrospective | China | 410 | 143/267 | I–IIIA | Surg | 54 [3–96] | 395.4 | OS | R | 7 |
| Guo (16) | 2018 | 2013–2016 | Retrospective | China | 140 | 45/95 | IIIB–IV | CRT | NR | 521 | OS/PFS | R | 6 |
| Li (17) | 2019 | 2013–2016 | Retrospective | China | 310 | 148/162 | IV | Mixed | NR | 1,218.81 | OS | R | 7 |
| Tomita (18) | 2018 | 2008–2012 | Retrospective | Japan | 341 | 168/173 | I–III | Surg | NR | 471.2 | CSS | R | 7 |
| Li (19) | 2018 | 2010–2012 | Retrospective | China | 181 | 54/127 | I–III | Surg | NR | 689 | OS/DFS | R | 8 |
| Wu (20) | 2018 | 2012–2015 | Retrospective | China | 128 | 30/98 | III–IV | CT | 36 [1–62] | 604.49 | OS | R | 7 |
| Wang (21) | 2018 | 2014–2015 | Retrospective | China | 30 | 14/16 | I–II | Surg | NR | 400 | DFS | E | 6 |
| Guo (22) | 2019 | 2006–2012 | Retrospective | China | 569 | 144/425 | I–III | Surg | 60.3 [0.9–146.7] | 419.6 | OS | R | 7 |
F, female; M, male; TNM, tumor-node-metastasis; NR, not reported; CRT, chemoradiotherapy; Surg, surgery; CT, chemotherapy; OS, overall survival; PFS, progression-free survival; CSS, cancer specific survival; DFS, disease-free survival; R, reported; E, estimated; HR, hazard ratio; NOS, Newcastle-Ottawa Scale.