Table 1. Main characteristic of included studies.
| First author | Year | NOS score | Country | Sample size | Gender (M/F) | Female (%) | Detection method | Tumor stage |
|---|---|---|---|---|---|---|---|---|
| Sun [16] | 2006 | 7 | China | 70 | 49/21 | 30 | IHC | I-III |
| Zhang [17] | 2009 | 6 | China | 52 | 30/22 | 42.3 | IHC | I-IV |
| Qin [18] | 2010 | 7 | China | 80 | 52/28 | 35 | IHC | I-III |
| Xu [22] | 2011 | 7 | China | 103 | 67/36 | 35 | IHC | I-IV |
| Li [23] | 2013 | 7 | China | 49 | 37/12 | 24.5 | IHC | IV |
| Liu [24] | 2015 | 6 | China | 94 | 44/50 | 53.2 | IHC | NR |
| Schalper [25] | 2016 | 7 | USA | 552 | 316/236 | 42.8 | QIF | I-IV |
| Wang [26] | 2016 | 8 | China | 316 | 160/156 | 49.4 | ELISA | I-IV |
| Xu [27] | 2016 | 7 | China | 128 | 80/48 | 37.5 | ELISA | I-IV |
Abbreviations: IHC: immunohistochemistry; QIF: quantitative immunofluorescence; ELISA: enzyme linked immunosorbent assay; NR: not reported.