Demographic characteristics of participating studies
| Study | Country | Study design | Cases | Controls | Female, n (%) | Median age (range) |
| Colo2&3 | USA | Case–control | 87 | 122 | 94 (45) | 65 (38–86) |
| DACHS | Germany | Case–control | 2363 | 2200 | 1820 (40) | 69 (33–99) |
| DALS | USA | Case–control | 1116 | 1174 | 1028 (45) | 64 (28–79) |
| HPFS | USA | Cohort | 483 | 685 | 0 (0) | 63 (48–82) |
| MEC | USA | Cohort | 314 | 334 | 305 (47) | 63 (45–76) |
| NHS | USA | Cohort | 837 | 1422 | 2259 (100) | 59 (44–69) |
| PHS | USA | Cohort | 367 | 384 | 0 (0) | 59 (40–85) |
| PLCO | USA | Cohort | 434 | 683 | 437 (39) | 65 (55–74) |
| PMH | USA | Case–control | 228 | 99 | 327 (100) | 63 (48–73) |
| VITAL | USA | Cohort | 254 | 263 | 239 (46) | 66 (50–76) |
| WHI | USA | Cohort | 1462 | 1527 | 2989 (100) | 66 (50–79) |
| Total | 7945 | 8893 | 9498 (56) | 65 (28–99) |
Colo 2&3, a case–control study from the University of Hawai’i; DACHS, Darmkrebs: chancen der Verhutüng durch Screening Study; DALS, diet, activity and lifestyle study; HPFS, Health Professionals Follow-up Study; MEC, multiethnic cohort; NHS, Nurses’ Health Study; PHS, Physicians’ Health Study; PLCO, Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial; PMH, the hormones and colon cancer study; VITAL, Vitamins and Lifestyle Study; WHI, Women's Health Initiative.