Selected micronutrients and colorectal cancer. a case-control study from the canton of Vaud, Switzerland

The association between dietary intake of various micronutrients and colorectal cancer risk was analysed using data from a case-control study conducted between 1992 and 1997 in the Swiss Canton of Vaud. Cases were 223 subjects (142 (64%) males, 81 (36%) females; median age 63 years) with incident, histologically confirmed colon (n=119; 53%) or rectal (n=104; 47%) cancer, and controls were 491 subjects (211 (43%) males, 280 (57%) females; median age 58 years; range 27-74) admitted to the same university hospital for a wide spectrum of acute non-neoplastic conditions, unrelated to long-term modifications of diet. Dietary habits were investigated using a validated food frequency questionnaire (FFQ). Odds ratios (OR) were obtained after allowance for age, sex, education, smoking, alcohol, body mass index, physical activity, and total energy and fibre intake. No significant association was observed for calcium, retinol, folate, vitamin D or E. The risk of colorectal cancer was directly associated with measures of iron intake (OR=2.43 for the highest tertile, 95% confidence interval (CI): 1.2-5.1) and inversely associated with vitamin C (OR=0.45; 95% CI: 0.3-0.8), and non-significantly with total carotenoids (OR=0.66, 95% CI: 0.4-1.1). Among various individual carotenoids considered, inverse associations were observed for alpha-carotene, beta-carotene and lutein/zeaxanthin. These findings were consistent across the strata of gender and age, and support the hypothesis that selected micronutrients have a favourable effect on colorectal carcinogenesis.     

Correlation between Food Consumption and Colorectal Cancer: An Ecological Analysis in Japan

Objectives: Incidence rates for colorectal cancer are universally high in western countries while values in theorient are very variable. Japan is one of the oriental countries with a high incidence but any association with foodcomponents remains to be clarified. To explore specific nutrient effects on risk of colorectal cancer in Japan, we hereconducted a correlation analysis between change in the diet and incidence rates.Methods: Incidence data for 1976-1996 and national values for per capita daily food nutrient intake in 1956-1995were used. We first analyzed chronological changes of food nutrients and colorectal cancer, and then calculatedcorrelation coefficients with time lags of 5, 10, 15 or 20 years. To adjust for the confounding effects of total energy, wealso performed a partial correlation analysis.Results: Incidences of colorectal cancer gradually increased during 1976-1996 with the highest incidence ratesfor colon and rectal cancers, 25.31 and 13.75 per 100,000, respectively, in 1996. Food nutrient intake also demonstratedmajor variation during 1956-1995, total fats and oils increasing most, followed by animal protein and animal fats.Incidences of colorectal cancer were positively associated with fat and oil intake, of both plant and animal types; apositive link was noted with animal protein but the association with plant protein consumption was inverse, as wasalso the case for carbohydrate and cereals; no simple association was evident with total energy intake.Conclusions: Food nutrients play roles in risk of colon and rectal cancers. Lower animal protein and fat intake,and higher carbohydrate and cereal consumption might reduce the risk of colon and rectal cancers.     

Physical activity, water intake and risk of colorectal cancer in Taiwan: a hospital-based case-control study.

The age-adjusted mortality rates of colorectal cancer have been rising in Taiwan over the past 2 decades, and colorectal cancer is now the third leading cause of cancer mortality in the country. We conducted a hospital-based case-control study to clarify the nature of the association between physical activity, water intake and colorectal-cancer risk in Taiwan. A total of 163 subjects (aged 33-80 years) with histologically confirmed primary colorectal cancer and 163 hospital controls were enrolled during 1992. Dietary intake, physical activity and other lifestyle activities were assessed using a comprehensive food-frequency and lifestyle-activity questionnaire. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic-regression analysis. A strong inverse dose-response relation between increased water intake and rectal cancer was found among men after adjustment for other risk factors (p for trend = 0.0005). The OR for rectal cancer among men in the highest tertile of water intake was 0.08 (95% CI, 0.02-0.35) compared with that among men in the lowest tertile (OR = 1). Similar but not significant trends were seen among women (p = 0.29). The OR for colon cancer among men with active leisure-time physical activity was 0.19 (95% CI, 0.05-0.77) times that among sedentary men (p for trend = 0.03). However, physical activity was not associated with colon-cancer risk among women (p = 0.48). No differences in the amount of water intake were found related to level of physical activity. These findings add to the evidence that leisure-time activity may reduce colon-cancer risk, not only in high-risk but also in low-risk populations, and support the potential beneficial effect of increased water intake in reducing colorectal-cancer risk.     

Macronutrient intake and risk of colorectal cancer in Italy

To provide further insight on the relationship between macronutrients and colorectal cancer, overall and by specific subsite(s), we carried out between 1992 and 1996 in 6 Italian areas a case-control study on 1,953 individuals of both sexes with incident colorectal cancer (age range 19–74) and 4,154 controls (age range 19–74) in hospital with acute, non-neoplastic diseases. A validated food-frequency questionnaire was used, including questions on 78 foods or recipes and on individual fat-intake pattern. The risk of cancer of the colon and rectum increased with total energy intake (odds ratio in highest vs. lowest quintile 1.43 and 1.50, respectively). The risk also rose significantly with an increase of starch intake, whereas it moderately decreased with an increase of protein intake. Monounsaturated fat intake appeared uninfluential, while saturated fat intake showed a modest direct association with rectal cancer. Polyunsaturated fat intake was inversely associated with colon cancer risk, particularly with the right colon. Int. J. Cancer 76:321–324, 1998.© 1998 Wiley-Liss, Inc.     

Flavonoids and colorectal cancer in Italy.

Because of their several biological activities, flavonoids may have an important role in explaining the protective effects of vegetables, fruit, and, possibly, tea against cancer. The potential relation between flavonoids and colorectal cancer risk was investigated using data from a multicentric Italian case-control study, including 1,953 cases of colorectal cancers (1,225 colon cancers and 728 rectal cancers) and 4,154 hospital controls admitted for acute nonneoplastic diseases. We have applied recently published data on the composition of foods and beverages, in terms of six principal classes of flavonoids, on dietary information collected through a validated food-frequency questionnaire. Odds ratios (OR) were estimated by multiple logistic regression models, including terms for sex, age, study center, family history of colorectal cancer, education, alcohol consumption, body mass index, physical activity, and energy intake. A reduced risk of colorectal cancer was found for increasing intake of isoflavones (OR, 0.76, for the highest versus the lowest quintile, P(trend) = 0.001), anthocyanidins (OR, 0.67, P(trend) < 0.001), flavones (OR, 0.78, P(trend) = 0.004), and flavonols (OR, 0.64, P(trend) < 0.001). No significant association was found for flavan-3-ols (OR, 0.98), flavanones (OR, 0.96), and total flavonoids (OR, 0.97). The estimates did not substantially differ for colon and rectal cancers, as well as in strata of sex, age, and body mass index. The findings of this large study provide support for an inverse association of selected classes of flavonoids with colorectal cancer risk.     

A case-control study of diet and colorectal cancer in a multiethnic population in Hawaii (United States): lipids and foods of animal origin

Temporal trend and migrant studies have indicated that the etiologyof colorectal cancer is predominantly environmental and, hence, modifiable.Animal fat intake has been frequently, but inconsistently, associated withthe risk of this disease. We conducted a population-based case-control studyin Hawaii (United States) among ethnic groups at different risks of thedisease to evaluate the role of dietary lipids and foods of animal origin onthe risk of colorectal cancer. We interviewed 698 male and 494 femaleJapanese, Caucasian (White), Filipino, Hawaiian, and Chinese patientsdiagnosed during 1987-91 with pathologically confirmed adenocarcinoma of thecolon or rectum, and 1,192 population controls matched to cases on age,gender and ethnicity. Odds ratios (OR), adjusted for caloric intake and otherdietary and non-dietary risk factors, were estimated using conditionallogistic regression. Intakes of total fat, saturated fat (S) andpolyunsaturated fat (P) were not related to the risk of colorectal cancer.However, an inverse association was found for the P/S ratio, with ORs of 0.6in both genders (95 percent confidence interval [CI] = 0.4-1.0 for males; CI= 0.3-0.9 for females) for the highest compared with the lowest quartile (P 0.05 for trend). Intakes of red meat and processed meat were associatedwith the risk of cancer in the right colon and rectum, respectively, in menonly. Fat-trimmed red meat and fish intakes were not related to risk. Chickeneaten without skin was associated inversely with risk in both genders. Thestrongest association was found for eggs, with an OR of 2.7 (CI = 1.7-4.0)and 2.3 (CI = 1.4-3.7) for the highest compared with the lowest quartile ofintake in men and women, respectively (P < 0.001 for trend). This associationwas dose-dependent, not explained by known confounders or other dietaryvariables, and was very consistent between genders, among ethnic groups, andacross all segments of the large bowel. These data sugg est that the ratio ofpolyunsaturated to saturated fat may be a better indicator of colorectalcancer risk than the absolute amount of specific fats in the diet. They alsosuggest that eggs and, possibly, untrimmed red meat and processed meatincrease, and chicken eaten without skin decreases, colorectal cancer risk.     

Foods as risk factors for colorectal cancer: a case-control study in Burgundy (France).

Although the high meat-low vegetable diet is considered the reference high-risk diet for colorectal cancer, particularly in USA communities, other at-risk dietary patterns, such as high intakes of processed meat and refined carbohydrates are emerging. Little is known about risk factors for colorectal cancer in France, a country at high risk of rectal cancer and moderately high risk of colon cancer. We compared diet of colorectal cancer cases (n = 171) and general population controls (n = 309) in Burgundy (France). Categories of intake were established by sex and based on the distributions of food intakes in controls. Odds ratios for the fourth vs first quartile of intake (OR4) were 2.0 (1.1-3.6) for refined cereal products (rice, pasta and pastry), 2.4 (1.3-4.5) for delicatessen, 2.3 (1.2-4.2) for patés, 1.7 (1.1-2.8) for offal and 2.1 (1.1-4.0) for butter, lard and cream. There was no association with consumption of fresh meat (OR4 = 1.2), fish (OR4 = 1.5), egg (OR4 = 1.1) or dairy products (OR4 = 1.0). A protective effect of vegetables was only observed for left colon cancer (OR3 = 0.3; 0.1-0.6). In men, the most significant risk factors were refined cereal products, seasoning animal fats, chocolate and coffee, whereas risk factors were delicatessen, fat meat, pasta, rice, and chocolate in women. The strong association with refined cereal products is consistent with the hypothesis of a role of hyperinsulinism in colorectal carcinogenesis. The association with processed but not fresh meat suggests the importance of exogenous carcinogenesis in that area.     

Allergy and other selected diseases and risk of colorectal cancer

It has been reported that allergy and other diseases may be related to colorectal cancer risk. The aim of this study was to perform a systematic analysis using information about medical histories specifically to see if there was any relation between allergies or other medical conditions and colorectal cancer risk. A multicentric case-control study was conducted in six Italian areas between 1992 and 1996 on 1225 incident cases of colon cancer, 728 cases of rectal cancer and 4154 controls comparable with cases according to sex and age group, admitted for acute conditions to the same network of hospitals where cases had been identified. Unconditional logistic regression models including terms for sex, age, study centre, years of education, body mass index, physical activity, smoking, history of colorectal cancer in first-degree relatives and energy intake were used to estimate the odds ratios (OR) of colon and rectal cancer according to history of allergy and other selected diseases. The OR for history of allergy was 0.88 (95% confidence interval, CI, 0.67-1.14) for colon and 0.64 (95% CI, 0.44-0.92) for rectal cancer, and the inverse association was stronger when allergy was diagnosed at age 35 years or more, or less than 10 years before the cancer diagnosis. No clear pattern emerged in strata of age and sex. History of other selected diseases, including hypertension and cholelithiasis, was not related to colon or rectal cancer risk, though there was a moderate increase in the risk of colon cancer (OR = 1.18, 95% CI, 0.66-2.14) in patients with a history of intestinal polyps. This study lends support to the hypothesis that allergic individuals may be at a lower risk of developing colorectal cancer.     

Intake of dietary folate vitamers and risk of colorectal carcinoma: results from The Netherlands Cohort Study

BACKGROUND: Several studies have reported inverse associations between folate intake and colorectal carcinoma risk. Few were prospective studies and none evaluated the association between the intake of individual folate vitamers and colorectal carcinoma risk. METHODS: The aim of the current study was to investigate the relationship between dietary folate intake and the risk of colorectal carcinoma in a large prospective cohort study in The Netherlands comprising 120,852 men and women aged 55-69 years. After 7.3 years of follow-up, 760 colon and 411 rectal carcinoma cases were available for analysis. Data processing and analysis used the case-cohort approach. A new Dutch database was used to estimate intakes of total and individual folate vitamers. RESULTS: Analyses adjusted for age, energy intake, family history of colorectal carcinoma, alcohol, vitamin C, iron, and dietary fiber intake yielded an inverse association between colon carcinoma risk and total dietary folate intake (rate ratio [RR]highest vs. lowest quintile, men: 0.73; 95% confidence interval [CI], 0.46-1.17, P trend = 0.03; women: 0.68; 95% CI, 0.39-1.20, P trend = 0.18). An inverse association between rectal carcinoma and total dietary folate intake was found only among men (RR highest vs. lowest quintile, men: 0.66; 95% CI, 0.35-1.21, P trend = 0.03). Analyses showed no clear difference in colorectal carcinoma risk associated with intake of different folate vitamers. CONCLUSIONS: Dietary folate intake was related inversely to colon and male rectal carcinoma risk.     

Calcium, vitamin D, sunshine exposure, dairy products and colon cancer risk (United States)

Objective: Epidemiologic studies on calcium, vitamin D and colon cancer are inconsistent, whereas experimental studies more regularly show a protective effect. To evaluate potential sources of inconsistencies, data from a large case–control study were analyzed, stratifying on potential effect modifiers. Methods: Data were collected by certified interviewers in Northern California, Utah and Minnesota. Analyses included 1993 incident colon cancer cases and 2410 population-based controls. Multivariate logistic regression models included age, sex, BMI, family history, physical activity, intake of energy, dietary fiber, aspirin and NSAIDs. Results: Dietary calcium was inversely associated with colon cancer risk in men (OR highest vs lowest quintile = 0.6, 95% CI = 0.5–0.9) and women (OR = 0.6, 95% CI = 0.4–0.9). No statistically significant associations were observed for dietary vitamin D or sunshine exposure. Consumption of total low-fat dairy products was associated with a statistically significantly decreased risk in men and women (ORs highest vs lowest category of intake = 0.8 and 0.7 respectively). Calcium supplement use was inversely associated with risk in both sexes (ORs use vs non-use = 0.8). Vitamin D supplements were inversely associated with risk in men (OR = 0.5) and women (OR = 0.6) but confidence limits included 1.0. Conclusions: These data provide additional support of an inverse association between high levels of calcium intake and colon cancer risk.     

Food groups and risk of oral and pharyngeal cancer

The role of specific food groups and diet variety on the risk of oral and pharyngeal cancer has been considered using data from a case-control study conducted between 1992 and 1997 in the Swiss Canton of Vaud. Cases were 156 patients (126 males, 30 females) aged under 75 (median age 56) years with incident, histologically confirmed cancer of the oral cavity and pharynx, and controls were 284 subjects (246 males, 38 females, median age 57 years), admitted to the same university hospital for a wide spectrum of acute, non-neoplastic conditions unrelated to tobacco and alcohol consumption or to long-term modification of diet. After allowance for education, alcohol, tobacco and total energy intake, significant trends of increasing risk with more frequent intake emerged for eggs (OR = 2.3 for the highest tertile), red meat (OR = 2.1) and pork and processed meat (OR = 3.2). Inverse trends in risk were observed for milk (OR = 0.4 for the highest tertile), fish (OR = 0.5), raw vegetables (OR = 0.3), cooked vegetables (OR = 0.1), citrus fruit (OR = 0.4) and other fruits (OR = 0.2). The addition of a serving per day of fruit or vegetables was associated with an about 50% reduction in oral cancer risk. The most favourable diet for oral cancer risk is therefore given by infrequent consumption of red and processed meat and eggs and, most of all, frequent vegetable and fruit intake. Diet diversity was inversely related to oral and pharyngeal cancer: ORs were 0.35 for the highest tertile of total diversity, 0.24 for vegetable and 0.34 for fruit diversity. In terms of attributable risk, high meat intake accounted for 49% of oral and pharyngeal cancers in this population, low vegetable intake for 65% and low fruit intake for 54%. Int. J. Cancer 77:705–709, 1998. © 1998 Wiley-Liss, Inc.     

Dietary folate and colorectal cancer

Folate may be inversely related to colorectal cancer risk, possibly in combination with low methionine and high alcohol consumption. We considered, therefore, the relation between folate and colorectal cancer in a multicentric case-control study of 1,953 cases and 4,154 controls from Italy, i.e., a population with frequent regular alcohol drinking. In the overall data set, the odds ratio (OR) was 0.72 for the highest quintile of folate, and the continuous OR per 100 microg was 0.86. The inverse relation was similar in men and women and somewhat stronger for the rectum (OR = 0.59 for the highest quintile) compared to the colon (OR = 0.81). It was also somewhat stronger in the highest tertile of alcohol drinking (OR = 0.65), though trends were not heterogeneous across strata of alcohol, whereas no appreciable difference was observed across strata of methionine intake. Compared to subjects reporting low alcohol, high methionine and high folate intake, the OR was 1.83 for those reporting high alcohol, low methionine and low folate intake. The present findings support a favorable role of folate in colorectal carcinogenesis.     

Dietary fats and colon cancer: Assessment of risk associated with specific fatty acids

There are many biological mechanisms whereby dietary fat and specific dietary fatty acids may alter risk of colon cancer in addition to their contribution to total energy intake. To evaluate these potential associations, we used detailed dietary intake data collected in a population-based study of 1,993 incident colon cancer cases and 2,410 controls conducted in 3 areas of the United States. The most commonly consumed fatty acid in the study population was oleic acid. One-third of dietary fats consumed came from additions to other foods at the table or from the preparation of other foods. After adjusting for total energy intake, physical activity and body size, neither total dietary fat nor specific fatty acids was associated with risk of colon cancer. However, among older women, fats from food preparation were associated with increased risk of colon cancer (OR 1.84, 95% CI 1.20–2.80), while fats from foods themselves or from additions to other foods were not. While dietary fats were not associated with colon cancer risk in the total population, subgroups of the population appeared to be at slightly greater risk if they consumed a high-fat diet. Women who consumed a diet high in mono-unsaturated fatty acids (MFAs) and poly-unsaturated fatty acids (PFAs) and who had a family history of colorectal cancer were at greater risk of colon cancer than those with similar intakes but without a family history of colorectal cancer. Similar associations with family history were noted among men diagnosed at younger ages for MFA, linolenic acid and 20-carbon PFA. Int. J. Cancer 73:670–677, 1997. © 1997 Wiley-Liss, Inc.     

Food groups and colorectal cancer risk

Most studies of diet and colorectal cancer have considered nutrients and micronutrients, but the role of foods or food groups remains open to debate. To elucidate the issue, we examined data from a case-control study conducted between 1992 and 1997 in the Swiss canton of Vaud. Cases were 223 patients (142 men, 81 women) with incident, histologically confirmed colon (n= 119) or rectal (n= 104) cancer (median age 63 years), linked with the Cancer Registry of the Swiss Canton of Vaud, and controls were 491 subjects (211 men, 280 women, median age 58 years) admitted to the same university hospital for a wide spectrum of acute non-neoplastic conditions unrelated to long-term modifications of diet. Odds ratios (OR) were obtained after allowance for age, sex, education, smoking, alcohol, body mass index, physical activity and total energy intake. Significant associations were observed for refined grain (OR = 1.32 for an increase of one serving per day), and red meat (OR = 1.54), pork and processed meat (OR = 1.27), alcohol (OR = 1.28), and significant protections for whole grain (OR = 0.85), raw (OR = 0.85) and cooked vegetables (OR = 0.69), citrus (OR = 0.86) and other fruits (OR = 0.85), and for coffee (OR = 0.73). Garlic was also protective (OR = 0.32 for the highest tertile of intake). These findings in a central European population support the hypothesis that a diet rich in refined grains and red meat increases the risk of colorectal cancer; they, therefore, support the recommendation to substitute whole grains for refined grain, to limit meat intake, and to increase fruit and vegetable consumption.     

Fat and K-ras mutations in sporadic colorectal cancer in The Netherlands Cohort Study

Associations between dietary intake of various fats and specific K-ras mutations in colorectal cancer (CRC) were investigated within the framework of The Netherlands Cohort Study on diet and cancer (NLCS). After 7.3 years of follow-up and with exclusion of the first 2.3 years, 448 colon and 160 rectal cancer patients and 2948 subcohort members (55-69 years at baseline) were available for data-analyses. Mutation analysis of the K-ras gene was performed on all archival colon and rectal adenocarcinoma specimens. Case-cohort analyses were used to compute adjusted incidence rate ratios (RR) and 95% confidence intervals (CI) for colon and rectal cancer cases and for K-ras mutation subgroups. The intake of total, saturated and monounsaturated fat was not significantly associated with colon or rectal cancer. High intake of dietary polyunsaturated fat and, specifically, linoleic acid is associated with an increased risk of mutated K-ras colon tumours. The RRs for 1 SD of increase of polyunsaturated fat and linoleic acid were 1.21 (95% CI 1.05-1.41) and 1.22 (95% CI 1.05-1.42), respectively, and similar associations were observed for both G > A transitions and G > T or G > C transversions in the colon. In contrast, no significant associations were observed with rectal cancer risk, overall nor with specific K-ras mutation status. A high intake of polyunsaturated fat, in particular linoleic acid, may be an important dietary risk factor for K-ras mutated colon tumours, possibly by generating G > A transitions or G > T or G > C transversions in the K-ras oncogene.     

Calcium, vitamin D, and apoptosis in the rectal epithelium.

OBJECTIVE: Decreased apoptosis in the colon is potentially an early indicator of colon cancer risk and may be influenced by calcium and vitamin D. This report describes the associations of calcium intake and 25-hydroxyvitamin D levels with apoptosis in colorectal epithelium. METHODS: Consecutive patients undergoing colonoscopies were recruited for a study designed to examine risk and etiologic factors for colorectal adenomas. Diet was assessed by food frequency questionnaire, and in one subpopulation, serum 25-hydroxyvitamin D levels were measured using an enzyme immunoassay. Apoptosis was scored from normal rectal mucosal pinch biopsies. Linear and logistic regression analyses were used to examine associations between calcium, serum vitamin D, and apoptotic scores. Data were available for 498 and 280 patients for the calcium and vitamin D analyses, respectively. RESULTS: Associations of calcium intake and vitamin D with apoptosis were modified by adenoma case-status. In an adjusted logistic regression model, patients with adenomas in the highest versus lowest tertile of dietary calcium intake had 3.4 times higher odds [95% confidence interval (CI), 0.9-12.9] of elevated apoptotic scores. In adenoma-free patients, high calcium intake was not related to apoptosis (OR, 1.2; 95% CI, 0.6-2.7). In contrast, the highest level of 25-hydroxyvitamin D was associated with higher apoptosis in adenoma-free patients (OR, 2.6; 95% CI, 1.1-6.2) and slightly lower levels in patients with adenomas (OR, 0.6; 95% CI, 0.2-2.2). CONCLUSION: These results are consistent with a calcium and vitamin D-mediated apoptotic mechanism in colon carcinogenesis.     

Dietary Fibre and the Risk of Colorectal Cancer: a Case-Control Study

Background: Colorectal cancer is one of the most commonly occurring cancers in China. Dietary fibre hasbeen thought to decrease the risk of colorectal cancer in Western countries. However, studies investigatingthe association between dietary fibre (particularly soluble and insoluble fibres) and colorectal cancer havehitherto been lacking in China. Objective: This case-control study examined the effect of dietary fibre intakeon the risk of colorectal cancer, stratified by tumour site. Materials and Methods: The study included 265 cases(colon cancer, 105; rectal cancer, 144; colon and rectal cancer, 16) and 252 controls residing in Qingdao. A foodfrequency questionnaire that included 121 food items was used to collect dietary information. Odds ratio (OR)and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis. Results:For food groups, controls in the study consumed more vegetables, soy food and total fibre than did colorectalcancer patients (p<0.05). The intakes of fruit, meat and sea-food did not differ significantly between cases andcontrols. However, we did not find any association between soy food intake and colon cancer. We observed inverseassociations between total fibre intake and colorectal, colon and rectal cancer (Q4 vs Q1: OR=0.44, 95%CI, 0.27-0.73; OR=0.40, 95%CI, 0.21-0.76; OR=0.52, 95%CI, 0.29-0.91). Vegetable fibre intake showed similar inverseassociations (Q4 vs Q1: OR=0.51, 95%CI, 0.31-0.85; OR=0.48, 95%CI, 0.25-0.91; OR=0.53, 95%CI, 0.29-0.97). Inaddition, inverse associations were observed between soluble fibre and insoluble fibre and both colorectal cancerand colon cancer. No relationship was found between colorectal cancer and fruit, soy or grain fibre intakewhenthe results were stratified by tumour site. Conclusions: The present study suggests that vegetable fibre and totalfibre play very important roles in protecting against colorectal cancer. Soluble and insoluble fibres were inverselyassociated with only colorectal cancer and colon cancer.     

A prospective study of dietary folate intake and risk of colorectal cancer: modification by caffeine intake and cigarette smoking.

Epidemiologic evidence indicates an inverse association of folate intake with risk of colorectal cancer, but whether this association is modified by intake of caffeine (in coffee and tea) or cigarette smoking--factors that possibly interfere with folate--has not been studied. Thus, we examined whether the association between dietary folate intake and incidence of colorectal cancer is modified by caffeine intake and smoking. Cox proportional hazards modeling was used to estimate rate ratios relating dietary folate intake to colorectal cancer incidence among 61,433 women ages 40 to 75 years at recruitment into the Swedish Mammography Cohort in 1987 to 1990. From March 1987 through June 2004, a total of 805 incident cases of colorectal cancer were diagnosed. After controlling for age and other potential confounders, we observed an inverse association between dietary folate intake and risk of colon cancer (rate ratio for the highest versus the lowest quintile, 0.61; 95% confidence interval, 0.41-0.91; P(trend) = 0.02), but not of rectal cancer (rate ratio, 0.93; 95% confidence interval, 0.55-1.56; P(trend) = 0.97). The inverse association between dietary folate intake and colon cancer risk was most pronounced among smokers (P(interaction) = 0.03). We found no apparent modification of risk by caffeine intake. Findings from this population-based cohort study support an inverse association between dietary folate intake and risk of colon cancer and suggest that smokers might benefit most from a high dietary folate intake.     

Iron and colorectal cancer risk in the alpha-tocopherol, beta-carotene cancer prevention study

In vitro and in vivo studies have associated iron with both the initiation and promotional stages of carcinogenesis. We investigated whether iron was associated with colorectal cancer in a nested case-control study within the alpha-tocopherol, beta-carotene cancer prevention study cohort. Exposure was assessed at baseline, using a 276-item food frequency questionnaire and a fasting serum sample. The study included 130 colorectal cancer cases (73 colon cancers and 57 rectal cancers) and 260 controls. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Supplemental iron intake was only reported for 4 cases and 18 controls; therefore, we were unable to obtain meaningful results for this variable. Comparing the highest to the lowest quartiles, there was an inverse association between serum ferritin and colorectal cancer risk (OR = 0.4, 95% CI = 0.2-0.9) and a suggestion of an inverse association between dietary iron and colorectal cancer risk (OR = 0.4, 95% CI = 0.1-1.1). In addition, serum ferritin, serum iron and transferrin saturation were all inversely associated with colon cancer risk specifically (OR = 0.2, 95% CI = 0.1-0.7, p trend = 0.02; OR = 0.2, 95% CI = 0.1-0.9, p trend = 0.05; OR = 0.1, 95% CI = 0.02-0.5, p trend = 0.003, respectively), whereas serum unsaturated iron binding capacity was positively associated with colon cancer risk (OR = 4.7, 95% CI = 1.4-15.1, p trend = 0.009). In summary, we found a significant inverse association between several serum iron indices and colon cancer risk.