Table 2 Smoking status: characteristics of studies included in the meta-analysis
Author | Year | Cancer site and type | Smokers | Nonsmokers | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Case | Control | Case | Control | |||||||||||
CC | CT | TT | CC | CT | TT | CC | CT | TT | CC | CT | TT | |||
Hua [17] | 2016 | bladder cancer | 187 | 308 | 73 | 250 | 229 | 52 | 219 | 257 | 75 | 368 | 391 | 104 |
Yang [8] | 2015 | gastric cancer | 44 | 60 | 20 | 49 | 68 | 24 | 116 | 186 | 74 | 144 | 167 | 48 |
Guo [23] | 2017 | oral squamous cell carcinoma | 35 | 75 | 30 | 81 | 131 | 49 | 66 | 106 | 50 | 174 | 217 | 88 |
Yuan [24] | 2018 | oral squamous cell carcinoma | 79 | 76 | 18 | 179 | 138 | 26 | 107 | 118 | 33 | 309 | 285 | 47 |
Yin [20] | 2018 | lung cancer | 0 | 0 | 0 | 0 | 0 | 0 | 204 | 264 | 88 | 165 | 172 | 58 |