Table 4.
Pooled relative risks of pancreatic cancer for total folate intake from both food and supplements*
| Study population | RR (95% CI) |
Ptrend‡ | Pbetween-studies heterogeneity§ | Pbetween-studies heterogeneity due to sex║ | ||||
| Quintile of total folate intake† | ||||||||
| 1 | 2 | 3 | 4 | 5 | ||||
| Men | ||||||||
| No. of cancers | 125 | 119 | 139 | 133 | 147 | |||
| Age-adjusted | 1.00 (referent) | 0.88 (0.69 to 1.14) | 1.00 (0.78 to 1.27) | 0.97 (0.75 to 1.26) | 1.02 (0.80 to 1.30) | .32 | .56 | |
| Multivariable¶ | 1.00 (referent) | 0.93 (0.72 to 1.20) | 1.09 (0.85 to 1.39) | 1.06 (0.80 to 1.41) | 1.14 (0.89 to 1.45) | .11 | .44 | |
| Women | ||||||||
| No. of cancers | 198 | 177 | 160 | 194 | 164 | |||
| Age-adjusted | 1.00 (referent) | 0.87 (0.71 to 1.07) | 0.78 (0.63 to 0.97) | 0.90 (0.74 to 1.11) | 0.77 (0.61 to 0.96) | .17 | .34 | |
| Multivariable¶ | 1.00 (referent) | 0.93 (0.76 to 1.14) | 0.85 (0.69 to 1.05) | 0.98 (0.79 to 1.21) | 0.85 (0.67 to 1.07) | .39 | .30 | |
| Men and women | ||||||||
| No. of cancers | 323 | 296 | 299 | 327 | 311 | |||
| Age-adjusted | 1.00 (referent) | 0.88 (0.75 to 1.03) | 0.87 (0.74 to 1.02) | 0.93 (0.80 to 1.09) | 0.87 (0.73 to 1.03) | .53 | .29 | .07 |
| Multivariable¶ | 1.00 (referent) | 0.93 (0.79 to 1.09) | 0.94 (0.80 to 1.11) | 1.01 (0.86 to 1.19) | 0.96 (0.80 to 1.16) | .90 | .22 | .07 |
Folate intake was adjusted for energy intake. The Melbourne Collaborative Cohort Study and the Canadian National Breast Screening Study were not included because total folate data were not available in these two studies. CI = confidence interval; RR = relative risk.
The quintiles were defined within each individual study. The Alpha-Tocopherol Beta-Carotene Cancer Prevention Study was excluded because folate intake in this study was primarily from diet; the Netherlands Cohort Study was also excluded because the folate intake in this study was only from food sources.
P values were calculated using two-sided Wald test.
P values were for the highest quintile and were calculated using the Q statistic.
P values were for the highest quintile and were calculated using the two-sided Wald test.
Adjusted for body mass index (kg/m2, continuous), diabetes (yes, no), alcohol intake (g/d; 0, 0.1–14.9, 15.0–29.9, ≥30), energy intake (kcal/d, continuous), and cigarette smoking (never, former [<15, ≥15 pack-years], current [<40, ≥40 pack-years]). Age in years and year of questionnaire return were included as stratification variables.