Table 1 The baseline characteristics of the eligible studies and included patients
Study | Country | Study design | Sample size | Age (years) | Male (%) | Stage (I–II/III–IV) | Interval from prior therapy to irradiation | Total radiation dose | Study quality |
|---|---|---|---|---|---|---|---|---|---|
Shioyama 2007 [19] | Japan | Retrospective | 82 | 61.0 | 85.4 | 57/24 | 10.0 months | 50.4 Gy | 6 |
Nonoshita 2007 [20] | Japan | Retrospective | 6 | 70.5 | 100.0 | 6/0 | 4.3 months | 22.8 Gy | 4 |
Maruyama 2011 [21] | Japan | Retrospective | 28 | 64.2 | 92.9 | 12/16 | NA | 60 Gy | 4 |
Kim 2012 [22] | Korea | Retrospective | 10 | 72.5 | 90.0 | 6/4 | 15.6 months | 46.5 Gy | 5 |
Zhou 2015 [23] | China | Retrospective | 55 | 66.8 | 49.1 | 54/1 | NA | 51.9 Gy | 6 |
Katano 2017 [24] | Japan | Retrospective | 6 | 60.8 | 100.0 | NA | 25.2 months | 50.4 Gy | 4 |
Hong 2018 [25] | China | Retrospective | 87 | 62.0 | 74.7 | 23/47 | 16.0 months | 60 Gy | 5 |
Xu 2019 [26] | China | Retrospective | 47 | 72.0 | 74.5 | 24/23 | 26.0 months | 58 Gy | 6 |
Zhao 2020 [27] | China | Retrospective | 252 | 69.0 | 81.7 | 79/173 | 30.0 months | 72 Gy | 6 |