Table 1. The characteristics of included studies.
| Study (year) | Country | Range of age | Sample Size(n) case/participant | Adjusted RR (95% CI) | Years of follow-up |
|---|---|---|---|---|---|
| Sidney et al. (1991) | USA | all years | 135/20476 | 1.0[0.7, 1.6] | 5 |
| Nienhuis et al. (1992) | England | 25–49 | 5/35446 | 0.44[0.1,4.0] | 16 |
| Giovannucci et al. (1193) | USA | 40–75 | 279/47855 | 1.66[1.25, 2.21] | 4 |
| Moller et al. (1994) | Denmark | N* | 165/73 917 | 0.98[0.84,1.14] | 12 |
| Hiatt et al. (1994) | USA | N | 238/43 432 | 0.8[0.5,1.3] | 14 |
| DeAntoni et al. (1997) | USA | 40–95 | N/95961 | 1.07[0.88,1.3] | 2 |
| Lynge et al. (2002) | Denmark | all years | 46/57931 | 0.98[0.73, 1.31] | 12 |
| Rohrmann et al. (2005) | USA | > 35 | 78/3373 | 2.03[1.24, 3.32] | 8 |
| Romero et al. (2012) | Brazil | > 40 | 58/2118 | 0.23[0.03, 1.70] | 5 |
| Siddiqui et al. (2014) | USA | 40–75 | 6023/49405 | 1.10[1.04, 1.17] | 24 |
Note: *: undefined.