Table 2.
The associations between intake of α-linolenic acid and lethal prostate cancer in the pre-PSA (1986–1994) and PSA (1994–2010) era
| Quintiles (Q) |
P interaction between two eras |
||||||
|---|---|---|---|---|---|---|---|
| Q1 | Q2 | Q3 | Q4 | Q5 | p trend | ||
|
|
|
||||||
| Pre-PSA eraa | |||||||
| Median intake, mg/d | 800 | 950 | 1,070 | 1,205 | 1,445 | ||
| Cases/person years | 63 / 71,601 | 78 / 71,472 | 74 / 71,335 | 88 / 73,909 | 83 / 71,435 | ||
| Age-adjusted model | 1 (ref) | 1.38 (0.98,1.93) | 1.32 (0.94,1.86) | 1.55 (1.11,2.15) | 1.44 (1.03,2.00) | 0.04 | 0.06 |
| Multivariable model 1c | 1 (ref) | 1.34 (0.96,1.88) | 1.27 (0.90,1.80) | 1.48 (1.06,2.05) | 1.41 (1.01,1.96) | 0.06 | 0.04 |
| Multivariable model 2d | 1 (ref) | 1.37 (0.98,1.93) | 1.32 (0.93,1.86) | 1.53 (1.10,2.14) | 1.46 (1.04,2.04) | 0.04 | 0.03 |
| + linoleic acid | 1 (ref) | 1.43 (1.01,2.02) | 1.43 (1.00,2.04) | 1.74 (1.22,2.48) | 1.78 (1.22,2.60) | 0.003 | 0.02 |
| PSA erab | |||||||
| Median intake, mg/d | 813 | 980 | 1,090 | 1,230 | 1,500 | ||
| Cases/person years | 71 / 107,198 | 68 / 106,862 | 95 / 107,187 | 74 / 106,580 | 66 / 106,813 | ||
| Age-adjusted model | 1 (ref) | 0.94 (0.68,1.31) | 1.06 (0.77,1.46) | 1.24 (0.91,1.69) | 0.83 (0.59,1.17) | 0.60 | |
| Multivariable model 1c | 1 (ref) | 0.93 (0.67,1.29) | 1.02 (0.74,1.41) | 1.17 (0.86,1.60) | 0.78 (0.55,1.09) | 0.32 | |
| Multivariable model 2d | 1 (ref) | 0.93 (0.66,1.29) | 1.02 (0.74,1.41) | 1.18 (0.86,1.61) | 0.77 (0.55,1.09) | 0.31 | |
| + linoleic acid | 1 (ref) | 0.94 (0.67,1.31) | 1.04 (0.75,1.45) | 1.21 (0.87,1.68) | 0.81 (0.56,1.17) | 0.53 | |
Analysis in the pre-PSA era was based on cumulatively updated ALA intake calculated from 1986 to 1990 FFQs
Analysis in the PSA era was based on cumulatively updated ALA intake calculated from 1994 to 2006 FFQs
Multivariable model 1 adjusted for age, calendar time, race (White, African American, Asian American, or other), current BMI (<21, 21 to 23, 23 to 25, 25 to 27.5, 27.5 to <30, or ≥ 30 kg/m2), height (quartiles), vigorous activity (quintiles, MET-hours/wk), smoking (never, former quit > 10 y ago, former quit ≤ 10 y ago, or current), family history of prostate cancer in father or brother (yes or no), diabetes (Type I or II, yes or no), multivitamin use (yes or no), history of PSA testing (yes or no, lagged by one questionnaire cycle), total calories (quintiles)
Multivariable model 2 includes all variables in model 1 and intakes of calcium (< 500, 500 to 750, 750 to 1000, 1000 to 1250, 1250 to 1500, 1500 to 2000, > 2000 mg/d), tomato sauce, coffee, supplemental vitamin E and marine omega3 fatty acids (all in quintiles).