|
|
||||||||
Original Research Communication |
1 From the Human Nutrition Research Center on Aging, Tufts University, Boston; the National Cancer Institute, Divisions of Cancer Epidemiology and Genetics and of Cancer Control and Population Sciences, Bethesda, MD; and the University of Nebraska Medical Center, Department of Pathology and Microbiology, Omaha.
2 Address reprint requests to MH Ward, Occupational Epidemiology Branch, National Cancer Institute, 6120 Executive Boulevard, EPS-8104, MSC-7420, Bethesda, MD 20892-7420. E-mail: wardm{at}exchange.nih.gov.
See corresponding editorial on page 5.
| ABSTRACT |
|---|
|
|
|---|
Objective: Our objective was to describe the dietary patterns of an eastern Nebraska population and investigate the associations between those dietary patterns and risks of adenocarcinoma of the esophagus and distal stomach.
Design: We recruited 124 subjects with esophageal adenocarcinoma, 124 subjects with distal stomach adenocarcinoma, and 449 control subjects in a population-based, case-control study.
Results: Six dietary patterns were identified with the use of cluster analysis. The first dietary pattern represented healthy food choices and had higher energy contributions from fruit and vegetables and grain products and lower energy contributions from red meats, processed meats, and gravy than did the other dietary patterns. In contrast, a second dietary pattern was high in meats and low in fruit and cereals. The other 4 dietary patterns were each characterized by a concentrated energy source: salty snacks, desserts, milk, and white bread, respectively. The test of overall difference in cancer risk across dietary patterns was significant for distal stomach adenocarcinoma (P = 0.04) but not for esophageal adenocarcinoma. Risk of esophageal adenocarcinoma was inversely associated with intakes of dairy products, fish, all vegetables, citrus fruit and juices, and dark bread and was positively associated with gravy intake. Risk of distal stomach adenocarcinoma was positively associated with red meat intake.
Conclusions: Our study suggests that a diet high in fruit and vegetables may decrease the risk of esophageal adenocarcinoma and that a diet high in meats may increase the risk of distal stomach adenocarcinoma.
Key Words: Esophagus stomach neoplasm dietary pattern cluster analysis cancer
| INTRODUCTION |
|---|
|
|
|---|
Dietary patterns were defined in various ways in previous studies, including multivariate methods such as cluster analysis and factor analysis. Subjects with different dietary patterns differ in socioeconomic status, health behaviors, total or disease-specific mortalities, and risks of diseases (911, 1524). Using factor analysis, Slattery et al (18) found that a Western diet high in processed meats, red meat, refined grain, and added sugar was associated with a higher risk of colon cancer, whereas a prudent diet high in fresh fruit, legumes, and vegetables was associated with lower risk. In another case-control study, a significant inverse association between the risk of gastric cancer and several food diversity scores was observed (16).
The incidence of esophageal adenocarcinoma is increasing at one of the fastest rates of any cancer in the United States, and the survival rates are poor (25). The association between dietary factors and risk of this cancer is not well understood. A few studies suggest that greater intakes of nutrients from plant sources, particularly from fruit and vegetables, may be associated with a lower risk and that greater intakes of dietary fat may be associated with a higher risk (2632). Unlike those for esophageal adenocarcinoma, the incidence of and mortality rates for stomach cancer have been decreasing for decades, and there is no clear explanation for the decrease (33). Studies suggest that diet plays an important role in the prevention of this cancer (34). To increase understanding of the role of dietary factors in the etiology of these cancers, we evaluated the associations between dietary patterns and cancer risks in a population-based, case-control study in eastern Nebraska.
| SUBJECTS AND METHODS |
|---|
|
|
|---|
21 y. The cases were limited to whites because the controls selected from an earlier study did not include other ethnic groups. The controls were randomly selected from the control group of a previous population-based, case-control study conducted in 19861987 in the same base population (35) and were frequency-matched to the overall distribution of all the cancer cases (including adult glioma patients) by age, sex, and vital status. Of those eligible, 137 esophageal adenocarcinoma cases, 170 stomach adenocarcinoma cases, and 502 controls completed interviews; overall response rates were 88%, 79%, and 83%, respectively. After the response rate of the controls in the previous study (87%) was taken into account, the adjusted response rate of the reinterviewed controls in the present study was 72%. The study protocol was approved by the Institutional Review Boards of the National Institutes of Health and the University of Nebraska Medical Center. After obtaining physician consent (for the cases), we sent a letter to the cases and controls that explained the study and invited participation. In a subsequent telephone call, we obtained informed consent from the cases, controls, or their next of kin (for deceased cases and controls) who were willing to participate in the telephone interview.
Interview and dietary assessment
Trained interviewers conducted telephone interviews of the cases and controls or their proxies during 19921994. Because of the poor prognoses of these cancers, interviews were conducted with the next of kin for 76% of esophageal adenocarcinoma cases, 80% of stomach adenocarcinoma cases, and 61% of controls. For the controls, self-respondents were intentionally oversampled to increase the power of subgroup analyses among self-respondents.
A modified version of the short Health Habits and History Questionnaire (36) was used for dietary assessment. In previous studies (36, 37), the short questionnaire was validated against the full questionnaire. Some food items, including several high-nitrate vegetables, onions, several processed meats, and fish, were added to the questionnaire. Subjects were asked to recall their frequency of consumption of 54 dietary items before 1985. Cases and controls with unknown intakes for
20% of the food items were excluded from the analyses (29). This left 124 (91%) esophageal adenocarcinoma cases, 154 (91%) stomach adenocarcinoma cases, and 449 (89%) controls. Of the stomach adenocarcinoma cases, 124 arose in the distal part of the stomach (hereafter called distal stomach cancer) and 30 in the stomach cardia. According to the Lauren classification (38), 47 of the 124 distal stomach cancer cases were of the diffuse type, 61 were of the intestinal type, 11 were of the mixed type, and 5 either were of other types or were not classifiable. Because of the small number of cardia cases and because cardia cancer is hypothesized to have different risk factors from distal stomach cancer, we excluded cardia cases from our analyses.
Statistical analysis
Before analysis of the data, the 54 food items were sorted into 24 different food groups. Definitions of food groups are shown in Appendix A
. Beyond major food groups as defined in the food guide pyramid, subgroups were defined on the basis of their similarity or difference in nutrient content. For example, meats from different animal sources differ in their specific fatty acid amounts and composition and therefore were grouped accordingly. The percentage of energy contributed from each food group was calculated and used in the cluster analysis. Standardization by energy contribution helps to remove dietary variations due to differences in sex, age, body size, and physical activity and to retain the proportionally based food-intake patterns.
|
5 times the SD from the mean. Second, because cluster analysis itself is a useful way to identify outliers, we ran the analyses with a predefined number of 20 clusters and removed those clusters with <5 subjects. Through both procedures, a total of 42 (9.4%) controls were identified as outliers and removed, leaving 407 eligible controls for the cluster generation. To find the most reasonable number of clusters, we ran a series of cluster analyses with predefined cluster numbers from 3 to 10 (22). We compared the ratios of between-cluster variance to within-cluster variance between all runs and constructed Scree plots to examine the ability of these clusters to segregate the study population. Then we scrutinized the food-intake patterns of each set of clusters to see which set provided the clearest separation that was nutritionally meaningful. Finally, we considered statistical power so that we would have reasonable sample sizes for further regression analysis. Once the cluster set was selected, we characterized these dietary patterns by examining their average energy contribution from each individual food group. Cases and outlier controls were finally classified into the nearest cluster by calculating the Euclidean distances between individual subjects and the presaved seed of each cluster.
In univariate analyses, we used one-factor analysis of variance or Student's t test to compare means and Mantel-Haenszel chi-square statistics to compare proportions, and multiple comparisons were adjusted with the Bonferroni method. Odds ratios (OR) and 95% CIs were calculated by unconditional logistic regression to estimate associations between individual dietary patterns or food groups and risks of the specific cancers. In the dietary pattern analyses, the healthy diet group was used as the reference, and individual 95% CIs and P values were Bonferroni-adjusted with the use of 99% CIs and P values that were multiplied by a factor of 5 to account for the 5 comparisons between each dietary pattern and the reference pattern. The P values for overall differences in cancer risks across dietary patterns were calculated by comparing the -2 log likelihood differences between models with and without the dietary pattern variables and a chi-square distribution with 5 degrees of freedom. All significance tests were two-sided (
= 0.05). In food-group analyses, we tested for a linear trend by including the median of each quartile as a continuous variable in the model and testing for the significance of the slope. We adjusted for age, sex, proxy status, energy intake, body mass index (BMI; in kg/m2), alcohol use, tobacco use, education, and vitamin supplement use for both cancer sites and age squared for esophageal adenocarcinoma. Family histories of esophageal cancer or gastrointestinal cancer were separately adjusted for esophageal adenocarcinoma and distal stomach cancer because they were associated with the risk in univariate analysis.
| RESULTS |
|---|
|
|
|---|
|
|
|
2-fold higher risk of esophageal adenocarcinoma was also found for the highsalty snacks dietary pattern (OR: 2.9; 95% CI: 0.85, 9.9), the high-milk dietary pattern (OR: 2.5; 95% CI: 0.64, 9.8), and the highwhite bread dietary pattern (OR: 2.6; 95% CI: 0.77, 8.7), and a
2-fold higher risk of distal stomach cancer was found for the high-milk dietary pattern (OR: 2.2; 95% CI: 0.68, 7.0). However, none of these comparisons were significant after Bonferroni adjustment for multiple comparisons.
|
50% lower risk compared with the lowest intake quartiles, and the inverse trends were significant. We also observed a 4060% lower risk for the highest intake quartiles of milk, poultry, dark-yellow vegetables, tomatoes, and total cereals compared with the lowest intake quartiles. Gravy intake was positively associated with a risk of esophageal adenocarcinoma. For distal stomach cancer, only higher intakes of red meat were significantly associated with greater risk.
|
| DISCUSSION |
|---|
|
|
|---|
The dietary patterns identified in the present study were associated with other demographic characteristics and health behaviors that may affect cancer risk, and these associations are consistent with those found in other studies (14, 18, 21, 40). Such associations show that dietary patterns are imbedded in larger health behavior patterns. This suggests target populations for nutritional education or intervention and points to the importance of considering dietary behavior in a wider context.
A few studies suggest that risk of esophageal adenocarcinoma is inversely associated with nutrient intake from plant sources and positively associated with dietary fat intake (2632). Our analyses of dietary patterns and food groups support these findings. For example, the healthy diet group tended to have the lowest risk of esophageal adenocarcinoma, and the high-meat group had a 3.6 times higher risk than did the healthy diet group. In addition, the high-meat group had an almost 3-fold higher risk for distal stomach cancer.
In our food-group analysis, a lower risk of esophageal adenocarcinoma was associated with greater intakes of foods that were frequently consumed in the healthy dietary pattern, including fruit and vegetables and dark bread. These foods are good sources of carotenoids, vitamin C, dietary fiber, and B vitamins, which have been shown to be inversely associated with a risk of esophageal adenocarcinoma (2628, 30, 32). The strongest inverse association with a risk of esophageal adenocarcinoma was found for the intake of fish, which was also more commonly consumed by the healthy diet group. Fish is a rich dietary source of n-3 fatty acids, including eicosapentaenoic acid and docosahexaenoic acid. These long-chain fatty acids can suppress mutation, inhibit cell growth, and enhance cell apoptosis, possibly by inhibiting eicosanoid production from n-6 fatty acids (4143). The healthy dietary pattern was also characterized by the lowest gravy intake, which had a strong positive association with risk of esophageal adenocarcinoma. In addition to its high fat content, gravy usually contains certain cooking carcinogens such as heterocyclic amines (44). For distal stomach cancer, only the intake of red meat was positively associated with risk, which supports the association we observed between the high-meat dietary pattern and distal stomach cancer. Although many other epidemiologic studies found significant inverse associations between intakes of fruit and vegetables and risk of stomach cancer, we did not.
The present study had several limitations. Although our questionnaire requested detailed information regarding intakes of vegetables and processed meats, it was a short version that included only 54 food items. Because of the poor survival rates for these cancers, a substantial amount of information was obtained from proxy respondents. Selection bias can occur if the dietary exposure distribution among dead controls differs from that of the base population (45). However, in the present study, proxy controls reported intakes similar to those reported by self-respondent controls for most food items after adjustment for age, sex, and energy intake. For example, the adjusted mean intakes of dark-yellow vegetables were 2.56 and 2.42 servings/wk for self-respondents and proxy controls, respectively. For citrus fruit and juices, adjusted mean intakes were 2.47 and 2.49 servings/wk, respectively. Information bias can be introduced if cases report intakes that were affected by symptoms of their cancers or that they believe were related to these cancers. However, we observed different associations with dietary patterns and food intakes for esophageal adenocarcinoma and distal stomach cancer, although both types of cancer may be perceived by the general population as having similar risk factors. Moreover, little was known about diet and esophageal adenocarcinoma at the time of the present study. Although recalled diet was found to be more closely associated with past diet than with current diet (46), recall over many years contains errors due to failures in memory (47). However, to the extent that such errors were random, they would have attenuated the observed associations.
Small sample sizes limited our power to detect statistical differences. Despite the relatively large magnitudes of the ORs in the dietary pattern analyses, none of the individual comparisons were significant after the conservative Bonferroni adjustment for multiple comparisons. Therefore, our results need to be confirmed in larger studies.
Cluster analysis is an empirical technique, and the selection of clusters is largely subjective. However, we performed the analyses with varying numbers of clusters and the results were similar. Moreover, the dietary patterns defined in this analysis were not established a priori but were instead based on the data. Finally, the nutritional implications of the 6 dietary patterns were generally understandable, making them directly useful for dietary guidance.
Cluster analysis is data dependent, and the generalizability of the results of this method is a concern. However, different investigations within various populations generated similar dietary patterns (14, 21, 22, 40, 48, 49), usually including high-meat, healthy, highwhite bread, and high-milk dietary patterns.
In summary, we found cluster analysis to be a useful tool for generating dietary patterns to investigate associations between diet and disease. Our results suggest that a diet high in fruit and vegetables and whole grains tends to reduce the risk of esophageal adenocarcinoma and that a diet high in meat tends to increase the risk of distal stomach adenocarcinoma.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
V. Edefonti, G. Randi, A. Decarli, C. La Vecchia, C. Bosetti, S. Franceschi, L. Dal Maso, and M. Ferraroni Clustering dietary habits and the risk of breast and ovarian cancers Ann. Onc., October 7, 2008; (2008) mdn594v1. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. P Mehta, A. P Boddy, J. Cook, V. Sams, E. K Lund, I. T Johnson, and M. Rhodes Effect of n-3 polyunsaturated fatty acids on Barrett's epithelium in the human lower esophagus Am. J. Clinical Nutrition, April 1, 2008; 87(4): 949 - 956. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. T. Campbell, M. Sloan, and N. Kreiger Dietary Patterns and Risk of Incident Gastric Adenocarcinoma Am. J. Epidemiol., February 1, 2008; 167(3): 295 - 304. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. L. Austin, L. S. Adair, J. A. Galanko, C. F. Martin, J. A. Satia, and R. S. Sandler A Diet High in Fruits and Low in Meats Reduces the Risk of Colorectal Adenomas J. Nutr., April 1, 2007; 137(4): 999 - 1004. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. L Hutton, L. Martin, C. J Field, W. V Wismer, E. D Bruera, S. M Watanabe, and V. E Baracos Dietary patterns in patients with advanced cancer: implications for anorexia-cachexia therapy. Am. J. Clinical Nutrition, November 1, 2006; 84(5): 1163 - 1170. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. C. Larsson, N. Orsini, and A. Wolk Processed meat consumption and stomach cancer risk: a meta-analysis. J Natl Cancer Inst, August 2, 2006; 98(15): 1078 - 1087. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. E Kelemen, J. R Cerhan, U. Lim, S. Davis, W. Cozen, M. Schenk, J. Colt, P. Hartge, and M. H Ward Vegetables, fruit, and antioxidant-related nutrients and risk of non-Hodgkin lymphoma: a National Cancer Institute-Surveillance, Epidemiology, and End Results population-based case-control study Am. J. Clinical Nutrition, June 1, 2006; 83(6): 1401 - 1410. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Kubo and D. A. Corley Body Mass Index and Adenocarcinomas of the Esophagus or Gastric Cardia: A Systematic Review and Meta-analysis. Cancer Epidemiol. Biomarkers Prev., May 1, 2006; 15(5): 872 - 878. [Abstract] [Full Text] [PDF] |
||||
![]() |
X. Gao, P. E. Wilde, A. H. Lichtenstein, and K. L. Tucker The 2005 USDA Food Guide Pyramid Is Associated with More Adequate Nutrient Intakes within Energy Constraints than the 1992 Pyramid J. Nutr., May 1, 2006; 136(5): 1341 - 1346. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. A. Gonzalez, P. Jakszyn, G. Pera, A. Agudo, S. Bingham, D. Palli, P. Ferrari, H. Boeing, G. del Giudice, M. Plebani, et al. Meat intake and risk of stomach and esophageal adenocarcinoma within the European Prospective Investigation Into Cancer and Nutrition (EPIC). J Natl Cancer Inst, March 1, 2006; 98(5): 345 - 354. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. R. Kristal, P. L. Blount, J. M. Schenk, C. A. Sanchez, P. S. Rabinovitch, R. D. Odze, J. Standley, T. L. Vaughan, and B. J. Reid Low-Fat, High Fruit and Vegetable Diets and Weight Loss Do Not Affect Biomarkers of Cellular Proliferation in Barrett Esophagus Cancer Epidemiol. Biomarkers Prev., October 1, 2005; 14(10): 2377 - 2383. [Abstract] [Full Text] [PDF] |
||||
![]() |
D M Clements, D A Oleesky, S C Smith, H Wheatley, D A Hullin, T J Havard, and D J Bowrey A study to determine plasma antioxidant concentrations in patients with Barrett's oesophagus J. Clin. Pathol., May 1, 2005; 58(5): 490 - 492. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. R. Olliver, L. J. Hardie, Y. Gong, S. Dexter, D. Chalmers, K. M. Harris, and C. P. Wild Risk Factors, DNA Damage, and Disease Progression in Barrett's Esophagus Cancer Epidemiol. Biomarkers Prev., March 1, 2005; 14(3): 620 - 625. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Cheong, K. Ivory, J. Doleman, M.L. Parker, M. Rhodes, and I.T. Johnson Synthetic and naturally occurring COX-2 inhibitors suppress proliferation in a human oesophageal adenocarcinoma cell line (OE33) by inducing apoptosis and cell cycle arrest Carcinogenesis, October 1, 2004; 25(10): 1945 - 1952. [Abstract] [Full Text] [PDF] |
||||
![]() |
W J Lee, W Lijinsky, E F Heineman, R S Markin, D D Weisenburger, and M H Ward Agricultural pesticide use and adenocarcinomas of the stomach and oesophagus Occup. Environ. Med., September 1, 2004; 61(9): 743 - 749. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Levi, C. Pasche, F. Lucchini, C. Bosetti, and C. La Vecchia Processed meat and the risk of selected digestive tract and laryngeal neoplasms in Switzerland Ann. Onc., February 1, 2004; 15(2): 346 - 349. [Abstract] [Full Text] [PDF] |
||||
![]() |
X. Gao, M. Yao, M. A. McCrory, G. Ma, Y. Li, S. B. Roberts, and K. L. Tucker Dietary Pattern Is Associated with Homocysteine and B Vitamin Status in an Urban Chinese Population J. Nutr., November 1, 2003; 133(11): 3636 - 3642. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Lin, O. I. Bermudez, and K. L. Tucker Dietary Patterns of Hispanic Elders Are Associated with Acculturation and Obesity J. Nutr., November 1, 2003; 133(11): 3651 - 3657. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. S. Engel, W.-H. Chow, T. L. Vaughan, M. D. Gammon, H. A. Risch, J. L. Stanford, J. B. Schoenberg, S. T. Mayne, R. Dubrow, H. Rotterdam, et al. Population Attributable Risks of Esophageal and Gastric Cancers J Natl Cancer Inst, September 17, 2003; 95(18): 1404 - 1413. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. L Erickson Dietary pattern analysis: a different approach to analyzing an old problem, cancer of the esophagus and stomach Am. J. Clinical Nutrition, January 1, 2002; 75(1): 5 - 7. [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||