1 Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, ... differential risks of colorectal cancer associated with dietary fatty acid intake.
IJC International Journal of Cancer
Dietary fatty acids, luminal modifiers, and risk of colorectal cancer Ikuko Kato1,2, Adhip P. Majumdar1,4,5, Susan J. Land1,3, Jill S. Barnholtz-Sloan6 and Richard K. Severson7 1
Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, USA Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan, USA 3 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan, USA 4 Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan, USA 5 John D. Dingell Veterans Affair Medical Center, Detroit, Michigan, USA 6 Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA 7 Department of Family Medicine and Public Health Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA 2
Epidemiology
Inconsistent observations in epidemiologic studies on the association between total fat intake and colorectal cancer may be ascribed to opposing effects of individual fatty acids and the presence of other dietary constituents that modify luminal or systemic lipid exposure. We analyzed the data from a population-based case-control study that included 1,163 cases and 1,501 controls to examine the effects of individual fatty acid groups on colorectal cancer risk as well as their interactions with calcium and fiber intake. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by unconditional logistic regression model according to quartile levels of energy-adjusted fatty acid intake. In the bivariable analyses, the risk of colorectal cancer increased with trans fatty acid (TFA) intake (OR for top vs. bottom quartile 51.46, 95% CI 1.17–1.59, pvalue for a trend ¼ 3 times per week for 6 months or longer) non-steroidal anti-inflammatory drug (NSAID) use, body mass index (body weight (kg)/body height (m)2), and physical activity index in their 30s, which was the weighted sum of time the subject spent per 24 h as described previously,21 pack–years of cigarette smoking and postmenopausal hormone replacement therapy (in women). The last two variables were forced to be included in the model given the evidence from the literature.19,20 Vitamin D, dietary heme, alcoholic drinks, race and body height were also assessed and were not included in the final model (p > 0.10). Major dietary sources of fatty acids, such as red meat, were not included in the model simultaneously because their inclusions (i.e., controlling their intake levels) alter the interpretation of regression coefficients for individual fatty acids. After exclusion of subjects with missing covariates, the final analytical samples in this study consisted of 1,163 cases and 1,501
Epidemiology
Material and Methods
943
944
Dietary fat and colorectal cancer
Table 1. Nutritional profile of the study population Overall (N52664)
Cases (N51163)
Controls (N51501)
Nutritional characteristics
Unit
Median
(Quartile range)
Median
(Quartile range)
Median
(Quartile range)
p-values
Total energy
Kcal/day
2040
(1581–2691)
2085
(1606–2801)
2023
(1563–2618)
0.004
Protein energy
%
14.8
(13.0–16.9)
14.6
(12.7–16.7)
15.0
(13.2–17.0)
0.002
Carbohydrate energy
%
47.8
(42.3–53.1)
47.6
(42.4–52.6)
48.0
(42.2–53.4)
0.306
Fat energy
%
37.4
(32.8–42.1)
37.8
(33.2–42.0)
37.1
(32.3–42.4)
0.184
Energy-adjusted intake Total fat
g/day
96.05
(86.21–106.46)
96.54
(86.73–106.11)
95.59
(85.99–106.86)
0.583
Saturated fatty acids
g/day
28.66
(25.18–32.32)
28.75
(25.51–32.36)
28.61
(24.86–32.32)
0.200
cis-MUFA
g/day
36.31
(31.90–40.66)
36.17
(32.00–40.66)
36.33
(31.81–40.67)
0.517
Omega-6 PUFA
g/day
20.21
(16.68–24.42)
19.95
(16.30–24.31)
20.39
(16.91–24.60)
0.019
Omega-3 PUFA
g/day
1.97
(1.66–2.41)
1.96
(1.65–2.40)
1.98
(1.67–2.42)
0.503
Trans fatty acid
g/day
7.71
(6.13–9.24)
7.86
(6.27–9.62)
7.60
(6.04–9.04)
0.004
Calcium
mg/day
899.6
(688.5–1307.7)
858.1
(662.1–1164)
946.0
(711.7–1417)
