Table 1.
Characteristics of the cohort studies included in the pooled analysis of folate intake and risk of pancreatic cancer*
| Study | Country | Follow-up period | Cohort, participants at baseline, No. | Age range at baseline, y | Pancreatic cancers, No. | Energy-adjusted median folate intake |
Multivitamin users, % | |
| (10th–90th percentile), μg/d | ||||||||
| Dietary folate | Total folate (dietary and supplemental) | |||||||
| Men | ||||||||
| ATBC Cancer Prevention Study | Finland | 1984–1999 | 26 987 | 50–69 | 204 | 256 (206–314) | 259 (207–329) | 8 |
| Cancer Prevention Study II Nutrition Cohort | United States | 1992–2001 | 66 165 | 50–74 | 210 | 310 (198–447) | 363 (212–777) | 33 |
| Cohort of Swedish Men | Sweden | 1998–2004 | 45 338 | 45–79 | 75 | 266 (201–354) | 278 (204–553) | 13 |
| Health Professional Follow-up Study | United States | 1986–2002 | 47 762 | 40–75 | 198 | 353 (242–514) | 404 (255–827) | 43 |
| Melbourne Collaborative Cohort Study | Australia | 1991–2003 | 14 908 | 40–69 | 28 | 280 (181–411) | NA | 13 |
| Netherlands Cohort Study | The Netherlands | 1986–1995 | 58 279† | 55–69 | 145 | 209 (158–294) | NA | 3 |
| New York State Cohort | United States | 1980–1987 | 30 363 | 15–107 | 90 | 409 (290–603) | 496 (307–874) | 38 |
| PLCO Cancer Screening Trial | United States | 1993–2004 | 29 914 | 55–74 | 90 | 436 (322–600) | 549 (345–1064) | 43 |
| Women | ||||||||
| Breast Cancer Detection Demonstration Project Follow-up Study | United States | 1987–1999 | 43 162 | 40–93 | 102 | 301 (183–503) | 382 (201–836) | 33 |
| Canadian National Breast Screening Study | Canada | 1980–2000 | 49 654† | 40–59 | 105 | 243 (168–343) | NA | NA |
| Cancer Prevention Study II Nutrition Cohort | United States | 1992–2001 | 74 138 | 50–74 | 164 | 271 (164–436) | 371 (181–779) | 42 |
| California Teachers Study | United States | 1995–2001 | 100 030 | 22–104 | 116 | 329 (237–458) | 487 (265–793) | 56 |
| Iowa Women’s Health Study | United States | 1986–2001 | 34 588 | 55–69 | 171 | 248 (169–364) | 281 (178–679) | 33 |
| Melbourne Collaborative Cohort Study | Australia | 1991–2003 | 22 830 | 40–69 | 35 | 260 (175–373) | NA | 19 |
| Netherlands Cohort Study | The Netherlands | 1986–1995 | 62 573† | 55–69 | 122 | 183 (135–260) | NA | 6 |
| New York State Cohort | United States | 1980–1987 | 22 550 | 15–107 | 48 | 378 (263–552) | 501 (289–861) | 49 |
| Nurses’ Health Study | United States | 1986–2002 | 68 478 | 40–65 | 178 | 274 (190–397) | 322 (202–709) | 43 |
| PLCO Cancer Screening Trial | United States | 1993–2004 | 28 315 | 55–74 | 60 | 366 (274–490) | 658 (308–1074) | 58 |
| Swedish Mammography Cohort | Sweden | 1987–2003 | 36 630 | 49–83 | 54 | 255 (184–356) | 278 (190–569) | 24 |
A total of 2195 incident pancreatic cancers (1040 men and 1155 women) were identified among 319 716 men and 542 948 women. Baseline cohort size and number of pancreatic cancers determined after applying study-specific exclusion criteria and excluding participants with previous cancer diagnosis other than non-melanoma skin cancer at baseline and natural log (loge)–transformed energy intake beyond three SDs from the study-specific loge-transformed mean energy intake of the population. ATBC = Alpha-Tocopherol Beta-Carotene; PLCO = Prostate, Lung, Colorectal, and Ovarian; NA = not applicable.
Canadian National Breast Screening Study and Netherlands Cohort Study are analyzed as case–cohort studies so the baseline cohort size does not reflect the above exclusions.