Table 1. Characteristics of the studies included in this meta-analysis.
| Author | Year | Country | Sample size | Age (years) | Sex (M/F) | Treatment | TNM stage | Types of outcomes | Cut-off value | Analysis | NOS score | Follow-up (months) | Study type | Study period |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Liu | 2015 | China | 455 | 59(19–86) | 314/141 | Surgery | I-III | OS | 0.25 | MV | 7 | 25(1–76) | Retrospective | 2005–2010 |
| Ni | 2016 | China | 258 | NR | 184/74 | Chemotherapy | IV | OS | 0.5897 | MV | 6 | 7(0.2–68) | Retrospective | 2010–2015 |
| Toiyama | 2016 | Japan | 384 | 67(32–88) | 264/120 | Surgery | I-III | OS, CSS | 0.051 | MV | 8 | 47.6 | Retrospective | 2001–2011 |
| Mao | 2017 | China | 337 | 59(19–89) | 237/100 | Mixed | I-IV | OS | 0.3778 | MV | 6 | NR | Retrospective | Jan-Dec, 2010 |
| Saito | 2018 | Japan | 453 | NR | 331/122 | Surgery | I-IV | OS | 0.0232 | UV | 6 | 61.9 | Retrospective | 2005–2013 |
| Toyokawa | 2018 | Japan | 240 | 64.5 | 168/72 | Surgery | II | OS | 0.03 | MV | 9 | 100.5 | Retrospective | 1997–2012 |
| Liu | 2019 | China | 688 | 57(21–86) | 449/239 | Mixed | II-III | CSS | 0.2 | MV | 8 | 36(3–162) | Retrospective | 2000–2012 |
| Lu | 2019 | China | 401 | 58.6 | 271/130 | Surgery | I-III | CSS | 0.143 | MV | 9 | 24(3–35) | Prospective | 2015–2016 |
M, male; F, female; NR, not reported; OS, overall survival; CSS, cancer-specific survival; MV, multivariate; UV, univariate; NOS, Newcastle-Ottawa Scale; TNM, tumor node metastasis.