A prospective study of diet and stomach cancer mortality in United States men and women.

Frequent consumption of fruits, vegetables, and whole grains has been associated with a reduced risk of stomach cancer in the majority of case-control studies of these factors: however, prospective studies have been less consistent. We examined the association between selected major food groups (citrus fruits, vegetables, whole grains, and processed meats) and risk of fatal stomach cancer in the Cancer Prevention Study (CPS) II cohort of 1.2 million United States men and women. During 14 years of follow-up, we documented 439 stomach cancer deaths in women and 910 in men after exclusion of individuals with prevalent cancers, inadequate diet information, and recent weight loss at baseline in 1982. After controlling for other risk factors, none of the food groups examined were associated with risk of stomach cancer except for an unexpected increased risk with vegetable consumption in women [relative risk (RR) = 1.25; 95% confidence interval (CI), 0.99-1.58; highest versus lowest tertile, P = 0.06 for trend]. A high overall plant food intake (a sum of vegetables, citrus fruit, and whole grains) was associated with reduced risk in men (RR = 0.79; 95% CI, 0.67-0.93; highest versus lowest tertile, P = 0.003 for trend), but not in women (RR = 1.18; 95% CI, 0.93-1.50; P = 0.16 for trend). Of individual foods examined, liver consumption greater than twice/week was associated with an increased risk of fatal stomach cancer in women (RR = 1.96; 95% CI, 1.09-3.53) and men (RR = 1.63; 95% CI, 1.02-2.62) compared with nonconsumers. This study supports a modest role for plant foods in reducing the risk of fatal stomach cancer in men, but not in women.     

A prospective study of whole grains, fruits, vegetables and colon cancer risk

OBJECTIVE: We examined the relation between whole grains, fruit, vegetables and dietary fiber and colon cancer risk in the prospective Cancer Prevention Study II Nutrition Cohort. METHODS: In 1992-1993, 62,609 men and 70,554 women completed questionnaires on medical history, diet and lifestyle behaviors. After exclusions, we confirmed 298 cases of incident colon cancer among men and 210 among women through August 31, 1997. RESULTS: Multivariate rate ratios (RR) and 95% confidence intervals (CI) for all dietary factors were null. However, a statistically non-significant 30% reduction in risk was observed for men with the highest vegetable intakes (RR = 0.69, CI = 0.47-1.03, top versus bottom quintile, p trend = 0.10). Men with very low (lowest tertile within the lowest quintile) intakes of vegetables and dietary fiber were at increased risk compared to those in the highest four quintiles of intake (vegetables RR = 1.79, CI = 1.22-2.61, p trend = 0.04, and fiber RR = 1.96, CI = 1.24-3.10, p trend = 0.006). Women with very low intakes of fruit were also at increased risk (RR = 1.86, CI = 1.18-2.94, p trend = 0.06). CONCLUSIONS: Higher intakes of plant foods or fiber were not related to lower risk of colon cancer. However, our data suggest that very low intakes of plant foods may increase risk, and that certain phytochemical subgroups may decrease risk.     

Dietary cadmium exposure and risk of postmenopausal breast cancer: a population-based prospective cohort study

The ubiquitous food contaminant cadmium has features of an estrogen mimetic that may promote the development of estrogen-dependent malignancies, such as breast cancer. However, no prospective studies of cadmium exposure and breast cancer risk have been reported. We examined the association between dietary cadmium exposure (at baseline, 1987) and the risk of overall and estrogen receptor (ER)-defined (ER(+) or ER(-)) breast cancer within a population-based prospective cohort of 55,987 postmenopausal women. During an average of 12.2 years of follow-up, 2,112 incident cases of invasive breast cancer were ascertained (1,626 ER(+) and 290 ER(-)). After adjusting for confounders, including consumption of whole grains and vegetables (which account for 40% of the dietary exposure, but also contain putative anticarcinogenic phytochemicals), dietary cadmium intake was positively associated with overall breast cancer tumors, comparing the highest tertile with the lowest [rate ratio (RR), 1.21; 95% confidence interval (CI), 1.07-1.36; P(trend) = 0.02]. Among lean and normal weight women, statistically significant associations were observed for all tumors (RR, 1.27; 95% CI, 1.07-1.50) and for ER(+) tumors (RR, 1.25; 95% CI, 1.03-1.52) and similar, but not statistically significant associations were found for ER(-) tumors (RR, 1.22; 95% CI, 0.76-1.93). The risk of breast cancer increased with increasing cadmium exposure similarly within each tertile of whole grain/vegetable consumption and decreased with increasing consumption of whole grain/vegetables within each tertile of cadmium exposure (P(interaction) = 0.73). Overall, these results suggest a role for dietary cadmium in postmenopausal breast cancer development.     

Diet and upper‐aerodigestive tract cancer in Europe: The ARCAGE study

There is suggestive, but inconclusive, evidence that dietary factors may affect risk of cancers of the upper aerodigestive tract (UADT). In the context of the alcohol‐related cancers and genetic susceptibility in Europe study, we have examined the association of dietary factors with UADT cancer risk. We have analyzed data from 2,304 patients with UADT cancer and 2,227 control subjects recruited in 14 centers in 10 European countries. Dietary data were collected through a semi‐quantitative food frequency questionnaire that also assessed preferred temperature of hot beverages. Statistical analyses were conducted through multiple logistic regression controlling for potential confounding variables, including alcohol intake and smoking habits. Consumption of red meat (OR per increasing tertile = 1.14, 95% CI: 1.05–1.25), but not poultry, was significantly associated with increased UADT cancer risk and the association was somewhat stronger for esophageal cancer. Consumption of fruits (OR per increasing tertile = 0.68, 95% CI: 0.62–0.75) and vegetables (OR per increasing tertile = 0.73, 95% CI: 0.66–0.81) as well as of olive oil (OR for above versus below median = 0.78, 95% CI 0.67–0.90) and tea (OR for above versus below median = 0.83, 95% CI 0.69–0.98) were significantly associated with reduced risk of UADT cancer. There was no indication that an increase in tea or coffee temperature was associated with increased risk of UADT overall or cancer of the esophagus; in fact, the association was, if anything, inverse. In conclusion, the results of this large multicentric study indicate that diet plays an important role in the etiology of UADT cancer. © 2008 Wiley‐Liss, Inc.     

Legume intake and the risk of cancer: a multisite case–control study in Uruguay

Background

Previous studies have suggested that a high intake of legumes may decrease the risk of stomach and prostate cancer and some other cancers. However, the evidence is still limited. To further explore the association between legume intake and cancer risk we conducted a case–control study of 11 cancer sites in Uruguay between 1996 and 2004, including 3,539 cancer cases and 2,032 hospital controls.

Results

The highest versus the lowest tertile of legume intake was associated with a significant decrease in the risk of cancers of the oral cavity and pharynx (OR = 0.48, 95% CI: 0.34–0.68), esophagus (OR = 0.54, 95% CI: 0.38–0.77), larynx (OR = 0.55, 95% CI: 0.40–0.77), upper aerodigestive tract (OR = 0.50, 95% CI: 0.40–0.63), stomach (OR = 0.69, 95% CI: 0.49–0.97), colorectum (OR = 0.43, 95% CI: 0.32–0.59), kidney (OR = 0.41, 95% CI: 0.24–0.71), and all sites combined (OR = 0.68, 95% CI: 0.59–0.78). No significant association was observed between legume intake and cancers of the lung (OR = 1.03, 95% CI: 0.83–1.27), breast (OR = 0.89, 95% CI: 0.65–1.20), prostate (OR = 0.87, 95% CI: 0.64–1.18) or bladder (OR = 0.82, 95% CI: 0.57–1.17). Similar results were found for both beans and lentils.

Conclusion

Higher intake of legumes was associated with a decreased risk of several cancers including those of the upper aerodigestive tract, stomach, colorectum, and kidney, but not lung, breast, prostate or bladder. Further investigations of these associations in prospective cohort studies are warranted.     

Relationship of diet to risk of colorectal adenoma in men.

BACKGROUND: Rates of colorectal cancer in various countries are strongly correlated with per-capita consumption of red meat and animal fat and inversely associated with fiber consumption. There have been few studies, however, of dietary risk factors for colorectal adenomas, which are precursors of cancer. PURPOSE: Our purpose was to determine prospectively the relationship between dietary factors and risk of colorectal adenomas. METHODS: Using data from the Health Professionals Follow-up Study, we documented 170 cases of adenomas of the left colon or rectum in 7284 male health professionals who completed a food-frequency questionnaire in 1986 and who had a colonoscopy or sigmoidoscopy between 1986 and 1988. Relative risk (RR) of adenoma was determined according to quintiles of nutrient intakes. RESULTS: After adjustment for total energy intake, saturated fat was positively associated with risk of colorectal adenoma (P for trend = .006); RR for the highest versus the lowest quintile of intake was 2.0 (95% confidence interval [CI] = 1.2-3.2). Dietary fiber was inversely associated with risk of adenoma (P for trend less than .0001); RR for men in the highest versus the lowest quintile was 0.36 (95% CI = 0.22-0.60). All sources of fiber (vegetables, fruits, and grains) were associated with decreased risk of adenoma. For subjects on a high-saturated fat, low-fiber diet, the RR was 3.7 (95% CI = 1.5-8.8) compared with those on a low-saturated fat, high-fiber diet. The ratio of the intake of red meat to the intake of chicken and fish was positively associated with risk of adenoma (P for trend = .02). CONCLUSIONS: These prospective data provide evidence for the hypothesis that a diet high in saturated fat and low in fiber increases the risk of colorectal adenoma. They also support existing recommendations to substitute chicken and fish for red meat in the diet and to increase intake of vegetables, fruits, and grains to reduce risk of colorectal cancer.     

Intake of fruits and vegetables and risk of cancer of the upper aero-digestive tract: the prospective EPIC-study

Epidemiologic studies suggest that a high intake of fruits and vegetables is associated with decreased risk of cancers of the upper aero-digestive tract. We studied data from 345,904 subjects of the prospective European Investigation into Cancer and Nutrition (EPIC) recruited in seven European countries, who had completed a dietary questionnaire in 1992–1998. During 2,182,560 person years of observation 352 histologically verified incident squamous cell cancer (SCC) cases (255 males; 97 females) of the oral cavity, pharynx, larynx, and esophagus were identified. Linear and restricted cubic spline Cox regressions were fitted on variables of intake of fruits and vegetables and adjusted for potential confounders. We observed a significant inverse association with combined total fruits and vegetables intake (estimated relative risk (RR) = 0.91; 95% confidence interval (95% CI) 0.83–1.00 per 80 g/d of consumption), and nearly significant inverse associations in separate analyses with total fruits and total vegetables intake (RR: 0.97 (95% CI: 0.92–1.02) and RR = 0.89 (95% CI: 0.78–1.02) per 40 g/d of consumption). Overall, vegetable subgroups were not related to risk with the exception of intake of root vegetables in men. Restricted cubic spline regression did not improve the linear model fits except for total fruits and vegetables and total fruits with a significant decrease in risk at low intake levels (<120 g/d) for fruits. Dietary recommendations should consider the potential benefit of increasing fruits and vegetables consumption for reducing the risk of cancers of the upper aero-digestive tract, particularly at low intake. Department of Epidemiology, German Institute of Human Nutrition, Potsdam-Rehbrücke     

Effects of alpha-tocopherol and beta-carotene supplementation on upper aerodigestive tract cancers in a large, randomized controlled trial

BACKGROUND: Although smoking and alcohol consumption are the major risk factors for upper aerodigestive tract cancers, observational studies indicate a protective role for fruits, vegetables, and antioxidant nutrients. METHODS: The authors examined whether daily supplementation with 50 mg dl alpha-tocopheryl acetate and/or 20 mg beta-carotene reduced the incidence of or mortality from oral/pharyngeal, esophageal, and laryngeal cancers in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) study, a double-blind, placebo-controlled primary prevention trial conducted in southwestern Finland. A total of 29,133 male smokers, aged 50-69 years and free of cancer at baseline, were randomized in a 2 x 2 factorial design to the supplementation regimen for 5-8 years (median, 6.1 years). Incident cancers of the oral cavity and pharynx (n = 65), esophagus (n = 24), and larynx (n = 56) were identified through the Finnish Cancer Registry. Intervention effects were assessed using survival analysis and proportional hazards models. RESULTS: There was no effect of either agent on the overall incidence of any upper aerodigestive tract cancer. For larynx, however, exploratory subgroup analyses were suggestive of a protective effect of beta-carotene supplementation on the incidence of early stage malignancies (stage I, relative risk [RR], 0.28, 95% confidence interval [CI]: 0.10-0.75). Neither agent affected mortality from these neoplasms. CONCLUSIONS: The results do not provide support for a protective effect of vitamin E or beta-carotene supplementation on upper aerodigestive tract cancers, although beta-carotene supplementation may impact the incidence of some subtypes of laryngeal tumors.     

Diet and risk of colon cancer in a large prospective study of older women: an analysis stratified on family history (Iowa, United States)

Objective: The purpose was to investigate whether dietary associations with risk of colon cancer in women differ by family history of the disease.Methods: Data were analyzed from a prospective cohort study of 35,216 Iowa (United States) women aged 55 to 69 years at baseline. Through 31 December 1995, 241 colon cancers were identified through record linkage with the State Health Registry. The cohort was stratified on family history of colon cancer in first-degree relatives; nutrient intakes were divided into tertiles.Results: Analyses using Cox regression revealed that the association of most dietary components with colon cancer incidence were similar for individuals with and without a family history. However, total calcium intake was associated inversely with colon cancer among women with a negative family history (relative risk [RR]=0.50 for upper cf lower tertile, P < 0.001), but was unrelated to incidence for women with a positive family history (RR=1.1 for upper cf lower tertile, P=0.69). Similarly, total vitamin E intake was associated with lower risk among women with a negative family history (RR=0.67 for upper cf lower tertile, P=0.04), but not among women with a positive family history (RR=0.87 for upper cf lower tertile, P=0.67). High intakes of fiber, fruits, and vegetables were each weakly inversely associated with risk among family-history negative women, but not among family-history positive women.Conclusions: These data, if corroborated, suggest that dietary factors typically associated with lower risk may be less effective risk-reduction interventions against colon cancer for individuals with a family history of colon cancer.     

Dietary factors and oral and pharyngeal cancer risk

We reviewed data from six cohort studies and approximately 40 case-control studies on the relation between selected aspects of diet and the risk of oral and pharyngeal cancer. Fruit and vegetables were inversely related to the risk: the pooled relative risk (RR) for high vegetable consumption was 0.65 from three cohort studies on upper aerodigestive tract cancers and 0.52 from 18 case-control studies of oral and pharyngeal cancer; corresponding RRs for high fruit consumption were 0.78 and 0.55. beta-carotene, vitamin C and selected flavonoids have been inversely related to the risk, but it is difficult to disentangle their potential effect from that of fruit and vegetables. Whole grain, but not refined grain, intake was also favorably related to oral cancer risk. The results were not consistent with reference to other foods beverages, and nutrients, but it is now possible to exclude a strong relation between these foods and oral and pharyngeal cancer risk. In western countries, selected aspects of diet may account for 20-25% of oral and pharyngeal cancer, and the population attributable risk increases to 85-95% when tobacco and alcohol consumption are also considered.     

Dietary folate intake and the risk of 11 types of cancer: a case–control study in Uruguay

BackgroundThere is limited, but inconclusive, epidemiological evidence that high folate intake decreases the risk of colorectal and esophageal cancers. For other cancer sites, the evidence is even less consistent or extensive.Materials and methodsWe conducted a case–control study of dietary folate intake and risk of 11 cancer sites in Uruguay between 1996 and 2004, including 3539 cancer cases and 2032 hospital controls. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of cancer associated with folate intake.ResultsIn the multivariable model, there was a significant decrease in the risk of cancers of the oral cavity and pharynx (OR = 0.49, 95% CI 0.24–0.98), esophagus (OR = 0.29, 95% CI 0.14–0.60), upper aerodigestive tract (OR = 0.41, 95% CI 0.26–0.65), colorectum (OR = 0.42, 95% CI 0.23–0.76) and kidney (OR = 0.35, 95% CI 0.13–0.93) for the highest versus the lowest quartile of dietary folate intake.ConclusionsOur results not only confirm earlier findings of decreased risk of colorectal and esophageal cancers with a high dietary folate intake but also suggest decreased risk of several other cancers. However, we cannot exclude the possibility that residual confounding, multiple comparisons or other forms of bias could explain these results.     

Dietary catechins and epithelial cancer incidence: the Zutphen elderly study

The flavonoids, a group of more than 4,000 polyphenolic antioxidants, are potential cancer preventive components of fruits and vegetables. Catechins, one of the 6 major groups of flavonoids, are present in high concentrations in tea as well. Our objective was to evaluate the association between intake of catechins and incidence of epithelial cancers with data from the Zutphen Elderly Study, a prospective cohort study among 728 men aged 65-84 years in 1985. The average catechin intake at baseline was 72 mg/day (range, 0-355 mg/day). After 10 years of follow-up, 96 incident epithelial cancers were recorded, including 42 cases of lung cancer. After multivariate adjustment, catechin intake was not associated with epithelial cancer (risk ratio [RR] from lowest to highest tertile: 1.00, 0.75, 0.94; p for trend: 0.82), or lung cancer (RR from lowest to highest tertile: 1.00, 0.72, 0.92; p for trend: 0.80). Catechins not from tea were borderline significantly inversely associated with lung cancer incidence (RR and 95% confidence interval [CI] for a 7.5-mg increase in intake: 0.66, 0.42-1.05), whereas catechins from tea were not. Catechins from apple, the major source of non-tea catechins, were also related to lung cancer incidence (RR and 95% CI for a 7.5-mg catechin increase: 0.67, 0.38-1.17). Because tea, the major catechin source in this population, was not associated with cancer risk, it seems unlikely that catechins are responsible for the observed inverse trend between non-tea catechins and lung cancer incidence. However, differences in bioavailability of the various catechins may play a role; effects on individual cancer sites cannot be excluded and merit further investigation.     

Prospective study of the association of alcohol with cancer of the upper aerodigestive tract and other sites

The association of alcohol consumption with cancers of the upper aerodigestive tract, hepato-biliary-pancreatic system, urogenital organs (except for prostate), and lymphohematopoietic tissue was evaluated in a prospective study of 6,701 American men of Japanese ancestry living in Hawaii. Compared with cancer-free subjects, subjects who subsequently developed cancers of the upper aerodigestive tract (oral-pharynx, esophagus, and larynx), liver, biliary tract, and lymphohematopoietic tissue consumed significantly larger amounts of total alcohol-mainly in the form of beer. Subjects who developed oral-pharyngeal and esophageal cancer also consumed larger amounts of wine and spirits. Because the upper aerodigestive tract cancers were associated positively with cigarette smoking, age-adjusted relative risks (RR) were calculated, based on joint exposure to cigarette smoking and heavy alcohol intake (30 ml/day) in this population. A markedly increased risk was observed among subjects who were both heavy alcohol drinkers and smokers (RR=17.3, 95 percent confidence interval [CI]=6.7–44.2), compared with subjects who did not smoke and did not drink heavily. The risk for these cancers also was increased among heavy alcohol drinkers who were nonsmokers (RR=8.6, CI=2.1–36.0).Dr Kato is currently with the Division of Epidemiology, Aichi Cancer Center Research Institute, Nagoya, Japan. Drs Nomura, Stemmermann, and Chyou are with the Japan-Hawaii Cancer Study, Kuakini Medical Center, Honolulu, HI. Address correspondence to Dr Nomura, Japan-Hawaii Cancer Study, Kuakini Medical Center, 347 N Kuakini St, Honolulu, HI 96817, USA. This work was supported in part by Grant RO1 CA 33644 from the National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.     

Dietary indicators of laryngeal cancer risk

The relationship between frequency of intake of a selected number of indicator foods and the risk of laryngeal cancer was investigated in a case-control study conducted in northern Italy on 110 males with histologically confirmed cancer of the larynx and 843 controls in the hospital for acute, nonneoplastic or respiratory diseases. Significant direct associations were observed with tobacco [relative risk (RR) = 5.8 for current versus never smokers] and alcohol (RR = 2.3 for the upper versus lower tertile of consumption), while the frequency of consumption of three food items was inversely related with laryngeal cancer risk. These were fish (RR = 0.6 for the upper tertile), green vegetables (RR = 0.4), and fresh fruit (RR = 0.3). Multiple logistic regression analysis, including simultaneously major nondietary covariates and various food items, suggested that the strongest and most consistent protective effect was given by fruit. These findings can be generally interpreted as an indication that a "poorer" diet is related to a raised risk of laryngeal cancer, although the confirmed observation that fruit appears to be the main protective dietary factor against cancers of the upper respiratory and digestive tract is of potential interest and may suggest useful etiological clues. Dietary findings were similar in different strata of alcohol and tobacco consumption.     

Intake of food groups and associated micronutrients in relation to risk of early-stage breast cancer.

Epidemiologic studies have evaluated the risk of breast cancer related to dietary fat intake, but only recently have other dietary factors received attention. Frequent intakes of fruit, vegetables and fiber have been associated with low risk of the disease in some studies but results are inconsistent. In a large case-control study of early-onset breast cancer, we evaluated risk related to a variety of food groups, associated micronutrients and non-nutritive constituents. Cases treated with chemotherapy appeared to have altered reporting of food intake and were excluded. Analyses were restricted to 568 cases with in situ and localized disease and 1,451 population-based controls. Reduced risks were observed for high intake of cereals and grains [odds ratio (OR) = 0.84, 95% confidence interval (CI) = 0.6-1.1 for highest compared with lowest quartile], vegetables (OR = 0.86, 95% CI = 0.6-1.1), beans (OR = 0.87, 95% CI = 0.7-1.2) and fiber from beans (OR = 0.88, 95% CI = 0.7-1.2). However, no trends of decreasing risk across quartiles of increasing intake were observed. Risk was not associated with dietary constituents related to these food groups including dietary fiber, carotenoids, vitamins A, C and E and folate. Incorporation of information from vitamin supplements did not alter the results for micronutrients. Our data suggest that intakes of cereals and grains, vegetables and beans are associated with minimal, if any, reduction in risk of early-stage breast cancer among young women.     

Vitamins C and E, retinol, beta-carotene and dietary fibre in relation to breast cancer risk: a prospective cohort study.

Association between breast cancer risk and the intake of vitamins C and E, retinol, beta (beta)-carotene, dietary fibre, vegetables, fruit and potatoes was examined in The Netherlands Cohort Study, for 62,573 women aged 55-69 years. After 4.3 years of follow-up, 650 incident breast cancer cases were identified. After adjusting for traditional risk factors, breast cancer risk was not influenced by the intake of beta-carotene, vitamin E, dietary fibre, supplements with vitamin C, vegetables or potatoes. Fruit consumption showed a non-significant inverse association with breast cancer risk (RR highest/lowest quintile = 0.76, 95% CI 0.54-1.08). A small reduction in risk was also observed with increasing intake of dietary vitamin C (RR highest/lowest quintile = 0.77, 95% CI 0.55-1.08). For retinol, a weak positive association was observed (RR highest/lowest quintile = 1.24, 95% CI 0.83-1.83). Among subjects with a high intake of polyunsaturated fatty acids (PUFAs), both beta-carotene and vitamin C intake showed a non-significant inverse association with breast cancer risk (P-trend = 0.15 and 0.16 respectively). Our findings do not suggest a strong role, if any, for intake of vitamins C and E, beta-carotene, retinol, dietary fibre, vegetables, fruit and potatoes in the aetiology of breast cancer.     

A prospective study of cruciferous vegetables and prostate cancer.

High intake of cruciferous vegetables may offer some protection against prostate cancer, but overall data are inconclusive. Thus, we examined the association between cruciferous vegetable intake and risk of prostate cancer in the Health Professionals Follow-Up Study. Between 1986 and 2000, 2,969 cases of nonstage T1a prostate cancer were diagnosed in 47,365 men who completed dietary assessments in 1986, 1990, and 1994. We calculated the multivariate relative risk (RR) and 95% confidence intervals (CIs) using Cox regression. Overall, we found no appreciable association between baseline intake of cruciferous vegetables and risk of prostate cancer (RR, 0.93; 95% CI, 0.82-1.05, for > or = 5 versus < or = 1 serving/week; P for trend = 0.30), and only a slight suggestive association for organ-confined prostate cancer (RR, 0.88; 95% CI, 0.74-1.05; P for trend = 0.06). The inverse association was stronger for men under the age of 65 years (RR, 0.81; 95% CI, 0.64-1.02; P for trend = 0.02), especially for organ-confined cancers (RR, 0.72; 95% CI, 0.54-0.97; P for trend = 0.007). In addition, this inverse association was stronger when we restricted the analysis to men with more consistent intake of vegetables over the 10 years before 1986, when we limited the analysis to men who had had a prostate-specific antigen test, and when we considered an 8-year time lag. This study does not provide compelling evidence of a protective influence of cruciferous vegetables on prostate cancer risk. However, if cruciferous vegetables are protective early in prostate carcinogenesis, as suggested by proposed mechanisms, we may expect stronger associations, as observed, for more remote diet for prostate-specific antigen-detected early stage (organ-confined) cancers in younger men. In contrast, for advanced cancers in older men, which were probably initiated decades in the past, recent dietary intakes of cruciferous vegetables may be irrelevant. These findings suggest that future studies of cruciferous vegetables should focus on early stages of prostate cancer.     

Dietary intakes of fruit,vegetables, and fiber,and risk of colorectal cancer in a prospective cohort of women (United States)

Objective: Although animal studies suggest an inverse association between consumption of plant foods and risk of colorectal cancer, many observational data have failed to support such an association. We prospectively examined the association between dietary intakes of fruit, vegetables, and fiber and colorectal cancer risk in a large female cohort from the Womens Health Study.Methods: Among 39,876 healthy women aged 45 years at baseline, 36,976 with baseline self-reported information on dietary intakes and other risk factors for colorectal cancer were included in the analyses. During an average follow-up of 10 years, 223 women were diagnosed with colorectal cancer. Intakes of fruit, vegetables, and fiber were assessed by a baseline food-frequency questionnaire. The analyses were carried out using the Cox proportional hazards regression and all tests were two-sided.Results: Intakes of fruit, vegetables, and the specific subgroups were not found to be associated with colorectal cancer risk. Multivariate relative risks (RRs) comparing the highest with lowest quintile were 0.79 (95% CI = 0.49–1.27,pfor trend = 0.30) for fruit intake, and 0.88 (95% CI=0.56–1.38,pfor trend=0.30) for vegetables intake. Similarly, intake of total fiber was not associated with colorectal cancer risk; the RR for the highest relative to lowest quintile was 0.75 (95% CI=0.48–1.17,pfor trend=0.12). However, higher intake of legume fiber was associated with a lower risk of colorectal cancer; the RR for the highestversuslowest quintile was 0.60 (95% CI=0.40–0.91,pfor trend=0.02).Conclusions: Our data offer little support for associations between intakes of fruit, vegetables, and fiber, and colorectal cancer risk. However, our data suggest that legume fiber and/or other related sources may reduce risk of colorectal cancer.     

Risk of colorectal and other gastro-intestinal cancers after exposure to nitrate, nitrite and N-nitroso compounds: a follow-up study

N-nitroso compounds are potent carcinogens detected in foodstuffs. The importance of dietary nitrosamines in relation to human cancer development is, however, uncertain. We studied the relationship between intake of nitrates, nitrites and N-nitrosodimethylamine (NDMA) and risk of cancers of the gastro-intestinal tract in a cohort of 9,985 adult Finnish men and women. During a follow-up period of up to 24 years, 189 gastro-intestinal cancer cases were diagnosed in the cohort, initially free from cancer. Intake of nitrate, nitrite and NDMA were estimated, based on food-consumption data from a 1-year dietary history interview covering the total diet of the participants. A significant positive association was observed between intake of NDMA and subsequent occurrence of colorectal cancer with a relative risk (RR) between the highest and lowest quartiles of intake of 2.12 [95% confidence interval (CI) 1.04-4.33]. Of various sources of N-nitroso compounds, intake of smoked and salted fish was significantly (RR = 2.58, 95% CI 1.21-5.51) and intake of cured meat was non-significantly (RR = 1.84, 95% CI 0.98-3.47) associated with risk of colorectal cancer. No similar association was observed for intake of other fish or other meat. No significant associations were observed between NDMA intake and cancers of the head and neck combined or of the stomach or between nitrate or nitrite intake and risk of cancers of the gastro-intestinal tract. Our results are in line with the idea that N-nitroso compounds can induce colorectal cancer in humans.     

Long-term dietary cadmium intake and postmenopausal endometrial cancer incidence: a population-based prospective cohort study

Environmental pollutants mimicking the effects of estrogen are suggested to contribute to the high incidence of hormone-related cancers, but supporting data are sparse. A potent estrogen-like activity of the pollutant cadmium, mediated via the estrogen receptor-alpha, has been shown in vivo. We prospectively examined the association between cadmium exposure and incidence of postmenopausal endometrial cancer. The Swedish Mammography Cohort is a population-based prospective cohort of 30,210 postmenopausal women free of cancer diagnose at baseline (1987) and who completed a food frequency questionnaire at baseline and in 1997. We estimated the dietary cadmium intake based on the questionnaire data and the cadmium content in all foods. During 16.0 years (484,274 person-years) of follow-up between the baseline and mid-2006, we ascertained 378 incident cases of endometrioid adenocarcinoma. The average estimated dietary cadmium intake was 15 mug/day (80% from cereals and vegetables). Cadmium intake was statistically significantly associated with increased risk of endometrial cancer in all women; the multivariate relative risk (RR) was 1.39 [95% confidence interval (CI), 1.04-1.86; P(trend) = 0.019], comparing highest tertile versus lowest. Among never-smoking women with body mass index (BMI) of <27 kg/m(2), the RR was 1.86 (95% CI, 1.13-3.08; P(trend) = 0.009). We observed a 2.9-fold increased risk (95% CI, 1.05-7.79) associated with long-term cadmium intake consistently above the median at both baseline 1987 and in 1997 in never-smoking women with low bioavailable estrogen (BMI of <27 kg/m(2) and nonusers of postmenopausal hormones). Our results support the hypothesis that cadmium may exert estrogenic effects and thereby increase the risk of hormone-related cancers.