Adenocarcinoma of the stomach and esophagus and drinking water and dietary sources of nitrate and nitrite.

We conducted a population-based case-control study of adenocarcinoma of the stomach and esophagus in Nebraska, U.S.A. Nitrate concentrations in public drinking water supplies were linked to residential water source histories. Among those using private wells at the time of the interview, we measured nitrate levels in water samples from wells. Dietary nitrate and nitrite were estimated from a food-frequency questionnaire. Among those who primarily used public water supplies (79 distal stomach, 84 esophagus, 321 controls), average nitrate levels were not associated with risk (highest versus lowest quartile: stomach OR=1.2, 95% CI [0.5-2.7]; esophagus OR=1.3, 95% CI [0.6-3.1]). We observed the highest ORs for distal stomach cancer among those with higher water nitrate ingestion and higher intake of processed meat compared with low intakes of both; however, the test for positive interaction was not significant (p=0.213). We did not observe this pattern for esophagus cancer. Increasing intake of nitrate and nitrite from animal sources was associated with elevated ORs for stomach cancer and with a significant positive trend in risk of esophagus cancer (P-trend=0.325 and 0.015, respectively). Larger studies with higher exposures to drinking water sources of nitrate are warranted to further evaluate N-nitroso compound precursors as risk factors for these cancers.

Drinking water and dietary sources of nitrate and nitrite and risk of glioma.

OBJECTIVE: Dietary nitrite has been associated with increased glioma risk; however, drinking water nitrate has not been extensively evaluated. METHODS: We conducted a population-based case-control study of adult glioma in Nebraska. Water utility nitrate measurements were linked to residential water source histories. We computed average nitrate exposure over a 20-year period. A food frequency questionnaire was used to assess dietary nitrate and nitrite. RESULTS: Increasing quartiles of the average nitrate level in drinking water were not significantly associated with risk (adjusted odd ratios: 1.4, 1.2, 1.3). Risk was similar among those with both higher and lower intakes of vitamin C, an inhibitor of N-nitroso compound formation. Dietary nitrite intake was not associated with risk. CONCLUSIONS: Our study does not support a role for drinking water and dietary sources of nitrate and nitrite in risk of adult glioma.

Hair dyes and risk of glioma among Nebraska women.

The etiology of brain cancer is not well understood. We conducted a population-based case-control study among 112 white women in Nebraska who were newly diagnosed with glioma between July 1988 and June 1993, and 215 controls, to identify risk factors for this disease. A 1.7-fold increased risk of glioma was observed for women who ever used hair coloring products (95% confidence interval (CI) = 1.0-2.9, 62 cases), and a 2.4-fold risk for those who used permanent hair coloring products (odds ratio (OR) = 2.4, 95% CI = 1.3-4.5, 39 cases). For women with the most aggressive form of glioma, glioblastoma multiforme, risk increased with duration of exposure to 4.9 (95% CI = 1.6-15.7, 10 cases) after 21 or more years of permanent hair coloring use. Higher risks were observed with earlier age at first use, but we did not see an exposure-response pattern with frequency of use of permanent dyes. No association was observed with use of non-permanent (sometimes called temporary or semi-permanent) hair coloring products. These suggestive findings need confirmation in future studies with larger sample sizes, fewer proxy respondents, and the ability to evaluate the effect of changes in formulations over time.

Gliomas and farm pesticide exposure in women: the Upper Midwest Health Study.

An excess incidence of brain cancer in male farmers has been noted in several studies, but few studies have focused on women. The National Institute for Occupational Safety and Health Upper Midwest Health Study evaluated effects of rural exposures for 341 female glioma cases and 528 controls, all adult (18-80 years of age) nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. On average, controls lived longer on farms than did cases. After adjusting for age, age group, education, and farm residence, no association with glioma was observed for exposure to arsenicals, benzoic acids, carbamates, chloroacetanilides, dinitroanilines, inorganics, organochlorines, organophosphates, phenoxys, triazines, or urea-based or estrogenic pesticides. An increased risk of glioma was observed for carbamate herbicides but was not statistically significant (odds ratio = 3.0; 95% confidence interval, 0.9-9.5). No association was observed between glioma and exposure to 12 widely used specific pesticides, after adjustment for age, age group, education, and any other pesticide exposure. These results were not affected after exclusion of proxy respondents (43% of cases, 2% of controls). Women were less likely than men to have applied pesticides, but more likely to have laundered pesticide-contaminated clothes. Storing pesticides in the house was associated with a statistically non-significant increased risk. Results show that exposure to pesticides was not associated with an increased risk of intracranial gliomas in women. Other farm-related factors could be etiologic factors and will be discussed in future reports.

Reproductive factors and risk of glioma in women.

OBJECTIVE: Glioma is the most common primary malignant brain tumor in adults, responsible for 75% of adult primary malignant brain tumors, yet aside from its association with ionizing radiation, its etiology is poorly understood. Sex differences in brain tumor incidence suggest that hormonal factors may play a role in the etiology of these tumors, but few studies have examined this association in detail. The objective of this study was to explore the role of reproductive factors in the etiology of glioma in women. METHOD: As part of a population-based case-control study, histologically confirmed primary glioma cases (n = 341 women) diagnosed between January 1, 1995 and January 31, 1997 were identified through clinics and hospitals in four Midwest U.S. states. Controls (n = 527 women) were randomly selected from lists of licensed drivers and Health Care Finance Administration enrollees. In-person interviews with subjects (81%) or their proxies (19%) collected reproductive history and other exposure information. RESULTS: Glioma risk increased with older age at menarche (P for trend = 0.009) but only among postmenopausal women. Compared with women who never breast-fed, women who breast-fed >18 months over their lifetime were at increased risk of glioma (odds ratio, 1.8; 95% confidence interval, 1.1-2.9). Women who reported using hormones for symptoms of menopause had a decreased risk of glioma compared with women who never used such hormones (odds ratio, 0.7; 95% confidence interval, 0.5-1.1). CONCLUSION: These results support the hypothesis that reproductive hormones play a role in the etiology of glioma among women.

Gliomas and farm pesticide exposure in men: the upper midwest health study.

The National Institute for Occupational Safety and Health evaluated farm pesticide exposure and glioma risk in a study that included 457 glioma cases and 648 population-based controls, all adult men (18-80 yr old) and nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. Multiple logistic regressions were used to control for farm residence, age, age group, education, and exposure to other pesticides. No associations were found between glioma and 12 specific pesticides. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) and found reduced glioma risk for insecticides (OR = 0.53, CI = 0.37-0.77), fumigants (OR = 0.57, CI = 0.34-0.95), and organochlorines (OR = 0.66, CI = 0.47-0.94). In analyses excluding proxy respondents (47% of cases) most CIs included 1.0. No positive association of farm pesticide exposure and glioma was found. Other farm exposures may explain the excess brain cancer risk seen in previous studies.

Application of a method to evaluate the quality of work histories and document the exposure assessment process.

BACKGROUND: Review of work history records by industrial hygienists is an important component of many occupational epidemiologic studies. A number of factors may influence the hygienist, such as the quality of the data and his or her previous experience. As part of a case-control study of mesothelioma, a system was developed to capture data on several factors that can be considered in a review of work history information. METHODS: The overall quality of the work history record was described by noting the completeness and the consistency of the information; for any potential exposures, the reviewer experience on which the decision was based and the relative quality of the information were categorized. Because of the potential for mesothelioma cases and their next-of-kin to have undergone rigorous questioning about previous asbestos exposure an evaluation of the knowledge of the respondent was included. The frequency and intensity of exposure were also evaluated. RESULTS: Evaluation of 3,444 work records is described. The importance of data completeness in the overall evaluation of quality is shown; follow-up questions regarding specific work tasks provide information not elicited in the standard interview process. The use of the literature was an important resource to the reviewer. Asbestos was reported by the respondent as an exposure on 149 work records; of these, 111 (74%) were judged to represent an unusual level of knowledge for a next-of-kin respondent. CONCLUSIONS: The approach presented allows capture of information about data quality and experience of the reviewer in an epidemiologic analysis. The ratings of frequency and intensity of exposure allow exploration of differences in exposure-response analyses using various exposure metrics.

An asbestos job exposure matrix to characterize fiber type, length, and relative exposure intensity.

The relationship between asbestos exposure and disease has been well documented, although questions persist as to variation in risk by the type and length of fiber. For a series of jobs with potential asbestos exposure, the primary fiber type (e.g., amosite, anthophylite, chrysotile, crocidolite, or tremolite) and fiber length were identified and the relative exposure intensity was estimated. The resulting job exposure matrix may be useful in epidemiological studies where asbestos is an exposure of interest.

Nutrient intakes and adenocarcinoma of the esophagus and distal stomach.

We studied the relationship between nutrient intakes and adenocarcinoma of the esophagus and distal stomach among 124 esophageal adenocarcinoma cases, 124 distal stomach cancer cases, and 449 controls in a population-based case-control study in eastern Nebraska. The residual method was used to adjust nutrient intake quartiles or tertiles for energy intake. We observed significant inverse associations with risk of esophageal adenocarcinoma for dietary intakes of total vitamin A [highest vs. lowest quartile, multivariate odds ratio (OR) = 0.5, P for trend = 0.05], beta-cryptoxanthin (OR = 0.5, P = 0.05), riboflavin (OR = 0.5, P = 0.01), folate (OR = 0.5, P = 0.03), zinc (OR = 0.5, P = 0.05), dietary fiber (OR = 0.5, P = 0.05), protein (OR = 0.5, P = 0.02), and carbohydrate (OR = 0.4, P = 0.02). For distal stomach cancer, only vitamin C (OR = 0.6, P = 0.04), dietary fiber (OR = 0.4, P = 0.007), and carbohydrate (OR = 0.4, P = 0.004) were inversely associated with risk. Our analyses showed significant interaction between dietary fat intake, but not intakes of other nutrients, and respondent type for both cancer sites. Subgroup analyses among self-respondents revealed positive associations between saturated fat intake and risk of esophageal adenocarcinoma (OR = 1.0, 4.1, and 4.6 for intake tertiles, P for trend = 0.02) and risk of distal stomach cancer (OR = 1.0, 1.2, and 3.6, P = 0.03). However, no such associations were found among proxy respondents. Our data suggest that greater intake of dietary fiber, certain carotenoids, and vitamins may decrease the risk of esophageal adenocarcinoma, whereas greater intake of saturated fat may increase the risk of esophageal adenocarcinoma and distal stomach cancer.

Diet and risk of adult glioma in eastern Nebraska, United States.

OBJECTIVE: To investigate potential associations between diet and adult glioma. METHODS: We conducted a population-based case-control study of adult glioma in eastern Nebraska. Nutrient and food group intakes were estimated for 236 glioma cases and 449 controls using information obtained from a food-frequency questionnaire. RESULTS: After adjusting for potential confounders, inverse associations with risk of adult glioma were observed for intakes of dark yellow vegetables (highest quartile versus lowest: OR = 0.6, Ptrend = 0.03) and beans (OR = 0.4, Ptrend = 0.0003), but no associations were seen for dietary sources of preformed nitrosamines or high-nitrate vegetables. Our nutrient analysis revealed significant inverse associations between risk of adult glioma and dietary intake of pro-vitamin A carotenoids (highest quartile versus lowest: OR = 0.5, Ptrend = 0.005), a-carotene (OR = 0.5, Ptrend = 001), beta-carotene (OR = 0.5, Ptrend = 0.01), dietary fiber (OR=0.6, Ptrend = 0.048) and fiber from beans (OR = 0.5, Ptrend = 0.0002). We observed no significant associations with risk of adult glioma for intakes of other nutrients or compounds including nitrate, nitrite, vitamin C, vitamin E, saturated fat, cholesterol, dietary fiber from grain products, or fiber from fruit and vegetables. CONCLUSION: Our study does not support the N-nitroso compound hypothesis, but suggests potential roles for carotenoids and possibly other phytochemicals in reducing risk of adult glioma.

Dietary patterns and adenocarcinoma of the esophagus and distal stomach.

BACKGROUND: Dietary pattern analysis is a unique approach to studying relations between diet and disease. 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.