Food consumption and cancer of the colon and rectum in north-eastern Italy

Unveiling the Effects of Cruciferous Vegetable Intake on Different Cancers: A Systematic Review and Dose-Response Meta-analysis

CONTEXT

Epidemiological studies indicated that cruciferous vegetable intake is associated with positive health outcomes. However, the role of cruciferous vegetables may have differential impacts on various cancers.

OBJECTIVE

This meta-analysis aims to review recent epidemiological studies on the link between cruciferous vegetables and various cancers. It seeks to identify the optimal intake dose and timing of cruciferous vegetables influencing their association with cancer risk.

DATA SOURCES

Studies on cruciferous vegetables and cancer were searched in PubMed, NCBI, Web of Science, and Elsevier databases from 1978 to June 2023.

DATA EXTRACTION

Extracted data from 226 relevant case-control and cohort studies were expressed by standardized mean difference and 95% CI, followed by the subgroup analysis to eliminate heterogeneity.

RESULTS

Intake of cruciferous vegetables can prevent cancers, with an odds ratio of 0.77 and risk ratio (RR) of 0.96. The intake levels of cruciferous vegetables associated with the risk of colorectal cancer, lung cancer, upper gastrointestinal cancer, gynecological cancer (ovarian cancer and endometrial cancer), bladder cancer, renal cancer, and prostate cancer were found to be 5.41 servings/week, 5.41 servings/week, 5.5 servings/week, 7.4 servings/week, 5.5 servings/week, 4.85 servings/week, and 3 servings/week, respectively. In a cohort followed for 2 to 15 years, limited consumption of cruciferous vegetables was correlated with a higher cancer RR. In the Asian population, cruciferous vegetables had a significant relationship with lung cancer, head and neck squamous cell carcinoma, and esophageal cancer. Conversely, cruciferous vegetables are predominantly associated with colorectal, renal, gynecological, and prostate cancer in the American population.

CONCLUSION

This study highlights the complex link between cruciferous vegetables and cancer, influenced by factors such as cancer type, region, intake level, and follow-up duration.

Egg Consumption and Risk of All-Cause and Cause-Specific Mortality: A Systematic Review and Dose-Response Meta-analysis of Prospective Studies

The association between egg consumption and mortality is extremely debatable. This study aimed to investigate the potential dose-response association of egg consumption with risk of mortality from all causes and cause-specific in the general population. The primary comprehensive literature search was conducted in PubMed/Medline, Scopus, ISI Web of Science, and Embase up to March 2021, as well as reference lists of relevant original papers and key journals. We calculated summary RRs and their 95% CIs for the highest and lowest categories, as well as the linear trend estimation of egg intake, using the random-effects model. Thirty-three (32 publications) cohort studies were included. These studies enrolled 2,216,720 participants and recorded 232,408 deaths from all causes. Comparing highest versus lowest egg intake categories was not associated with the risk of mortality from all causes (RR: 1.02; 95% CI: 0.94, 1.11; n = 25), cardiovascular disease (CVD) (RR: 1.04; 95% CI: 0.87, 1.23, n = 11), coronary heart disease (CHD) (RR: 0.98; 95% CI: 0.84, 1.16; n = 10), stroke (RR: 0.81; 95% CI: 0.64, 1.02; n = 9), and respiratory disease (RR: 0.96; 95% CI: 0.53, 1.71; n = 3); however, it was associated with a higher risk of cancer mortality (RR: 1.20; 95% CI: 1.04, 1.39; n = 13). In the linear dose-response analysis, an additional intake of 1 egg per week was associated with a 2% and 4% increased risk of all-cause and cancer mortality, respectively, and a 4% decreased risk of stroke mortality. The certainty of the evidence was rated as low to moderate. Higher egg consumption was not associated with an increased risk of mortality from all causes, CVD, CHD, stroke, or respiratory disease, whereas an elevated risk was observed for cancer mortality. These findings suggest that eggs be consumed in low to moderate amounts (≤1 egg/d) as part of a healthy diet.

Olive oil intake and cancer risk: A systematic review and meta-analysis

BACKGROUND

Research evidence has established the beneficial effects of diet in cancer prevention; various epidemiological studies have suggested that olive oil component could play a role in decreasing cancer risk. This systematic review and meta-analysis aims to investigate the association between olive oil consumption, cancer risk and prognosis.

METHODS

A systematic search was conducted in PubMed, EMBASE and Google Scholar databases (end-of-search: May 10, 2020). Pooled relative risk (RR) and 95% confidence intervals (95% CIs) were estimated with random-effects (DerSimonian-Laird) models. Subgroup analyses, sensitivity analyses and meta-regression analysis were also performed.

RESULTS

45 studies were included in the meta-analysis; 37 were case-control (17,369 cases and 28,294 controls) and 8 were cohort studies (12,461 incident cases in a total cohort of 929,771 subjects). Highest olive oil consumption was associated with 31% lower likelihood of any cancer (pooled RR = 0.69, 95%CI: 0.62-0.77), breast (RR = 0.67, 95%CI: 0.52-0.86), gastrointestinal (RR = 0.77, 95%CI: 0.66-0.89), upper aerodigestive (RR = 0.74, 95%CI: 0.60-0.91) and urinary tract cancer (RR = 0.46, 95%CI: 0.29-0.72). Significant overall effects spanned both Mediterranean and non-Mediterranean participants, studies presenting a multivariate and a univariate analysis and all subgroups by study quality.

CONCLUSIONS

Olive oil consumption seems to exert beneficial actions in terms of cancer prevention. Additional prospective cohort studies on various cancer types and survivors, as well as large randomized trials, seem desirable.

Sucrose Intakes and Incident Colorectal Cancer Risk among Women

BACKGROUND

High sucrose intakes are hypothesized to increase colorectal cancer (CRC) risk by several mechanisms, and sucrose intakes have been consistently positively associated with CRC risk in case-control studies. However, all but one prospective study reported a null sucrose-CRC association. The only prospective study to report a positive association was the Iowa Women's Health Study (IWHS) of 35,221 cancer-free Iowa women, aged 55 - 69 years old at baseline in 1986, after four years of follow up.

MATERIALS AND METHODS

To address the discrepant findings in the literature, after 26 years of follow up in the IWHS, we updated and expanded on our earlier reported analyses. During follow up through 2012, 1,731 women were diagnosed with CRC. Baseline dietary intakes were assessed with a Willett semiquantitative food frequency questionnaire. We used multivariable Cox proportional hazards regression models to estimate adjusted hazards ratios (HRs) and their 95% confidence intervals (CI).

RESULTS

For those in the highest relative to the lowest intake quintiles, the adjusted HRs (95% CI) for CRC were 1.04 (0.87-1.23; Ptrend = 0.59) for sucrose, 1.00 (0.82-1.21; Ptrend = 0.67) for sucrose-containing foods, and 1.01, (0.83-1.22; Ptrend = 0.56) for nondairy sucrose-containing foods, respectively. These findings did not differ substantially by colorectal site or according to categories of selected participant characteristics.

CONCLUSIONS

Our findings do not support that intakes of sucrose or sucrose-containing foods are substantially associated with CRC risk among older women.

Risk of Colorectal Cancer in a Brazilian Population is Differentially Associated with the Intake of Processed Meat and Vitamin E

The incidence and mortality rates of colorectal cancer (CRC) in Northeast Brazil are increasing. To study the association between CRC and diet, data were obtained from 64 patients with CRC and 123 sex- and age-matched controls. The dietary details were recorded using a validated food frequency questionnaire. Nutrient intake was calculated using Dietsys software (National Cancer Institute, Maryland, USA). In a binary logistic regression model of dietary components (model 1), the chance of CRC increased by 0.2% (odds ratio [OR] = 1.002; 95% confidence interval [CI]: 1.000-1.004) for each gram of processed meat intake per week (p < 0.010). Consumption of eggs decreased the chance by 0.1% per gram (OR = 0.999; 95% CI: 0.998-1.000; p < 0.050). The use of oil (including olive oil) for served food decreased the chance by 1.8% (OR = 0.982; 95% CI: 0.970-0.992) for each time consumed (p < 0.010). In a model of nutritional factors (model 2), intake of vitamin E decreased the chance by 16.8% (OR = 0.832; 95% CI: 0.725-0.940) for each milligram intake per week (p < 0.010). In model 1 and 2 smoking increased the chance of CRC by 10.294 (95%CI: 4.240-27.670) and 2.496 (95% CI: 1.425-3.566) times (p < 0.010; p < 0.010), respectively.

Potato Consumption and Risk of Site-Specific Cancers in Adults: A Systematic Review and Dose-Response Meta-Analysis of Observational Studies

The etiology of cancer type may vary significantly due to anatomy, embryology, and physiology of the cancer site. Although the association between potato consumption and colorectal cancer (CRC) was summarized in a 2018 meta-analysis of 5 cohort studies, to the best of our knowledge, no meta-analysis has evaluated potato consumption in relation to multiple cancer sites in adults. Medline/PubMed, ISI Web of Knowledge, Scopus, and the Cochrane Database of Systematic Reviews were searched for relevant publications through August 2020. We selected cohort or case-control studies conducted in adults that reported risk estimates (relative risk [RRs], HRs, and ORs) of potato intake for any cancer type. Random effects meta-analyses compared high and low intake categories. Twenty prospective cohort studies (total n = 785,348) including 19,882 incident cases, and 36 case-control studies (21,822 cases; 66,502 controls) were included. Among cohort studies, we did not find an association between high versus low intake of total potato (white and yellow) consumption and overall cancers: 1.04 (95% CI: 0.96, 1.11; tau2 = 0.005, n = 18). We found no relation between total potato consumption (high compared with low intake) and risk of CRC, pancreatic cancer, colon, gastric, breast, prostate, kidney, lung, or bladder cancer in cohort or case-control studies. We did not find an association between high versus low consumption of potato preparations (boiled/fried/mashed/roasted/baked) and risk of gastrointestinal-, sex-hormone-, or urinary-related cancers in cohort or case-control studies. Certainty of the evidence was low for total cancer, CRC, colon, rectal, renal, pancreatic, breast, prostate, and lung cancer and very low for gastric and bladder cancer. In conclusion, potato intake or potato preparations were not associated with multiple cancer sites when comparing high and low intake categories. This finding was consistent with the findings from the 2018 meta-analysis regarding potato intake and risk of CRC.

Whole Grains, Refined Grains, and Cancer Risk: A Systematic Review of Meta-Analyses of Observational Studies

PubMed, Web of Science, and the Cochrane Database of Systematic Reviews were searched for meta-analyses that provided risk estimates (±95% confidence intervals) for associations between intakes of whole and refined grains and risk of total and site-specific cancer. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. Only meta-analyses that included whole grains and refined grains as separate food groups, and not as part of dietary patterns, were included. A total of 17 publications were identified that met inclusion criteria. Within these, results from a total of 54 distinct meta-analyses were reported for whole grains and 5 meta-analyses for refined grains. For total cancer mortality, 7 meta-analyses of cohort studies indicated that whole grain intake was associated with 6% to 12% lower risk in comparison of highest vs. lowest intake groups, and 3% to 20% lower risk for doses ranging from 15 to 90 g/day. For site-specific cancers, meta-analyses indicated that whole grain intake was consistently associated with lower risks of colorectal, colon, gastric, pancreatic, and esophageal cancers. Limited data were available for refined grains, with only 4 publications providing risk estimates, and only 1 of the meta-analyses included more than 3 studies. High intake of refined grains was associated with increased risk of colon and gastric cancer. By contrast, in the only dose-response meta-analysis, each 90 g/day consumption of refined grains was associated with a 6% lower risk of total cancer. In addition to the limited number of published meta-analyses on refined grains, results were also weakened due to the fact that refined grains were frequently defined to include both staple grain foods and indulgent grain foods, and the majority of studies included in the meta-analyses provided no specific definition of refined grains. Overall, meta-analyses of cohort and case-control studies consistently demonstrate that whole grain intake is associated with lower risk of total and site-specific cancer, and support current dietary recommendations to increase whole grain consumption. By contrast, the relationship between refined grain intake and cancer risk is inconclusive.

A Review of the In Vivo Evidence Investigating the Role of Nitrite Exposure from Processed Meat Consumption in the Development of Colorectal Cancer

The World Cancer Research Fund (WCRF) 2007 stated that the consumption of processed meat is a convincing cause of colorectal cancer (CRC), and therefore, the public should avoid it entirely. Sodium nitrite has emerged as a putative candidate responsible for the CRC-inducing effects of processed meats. Sodium nitrite is purported to prevent the growth of Clostridium botulinum and other food-spoiling bacteria, but recent, contradictory peer-reviewed evidence has emerged, leading to media reports questioning the necessity of nitrite addition. To date, eleven preclinical studies have investigated the effect of consuming nitrite/nitrite-containing meat on the development of CRC, but the results do not provide an overall consensus. A sizable number of human clinical studies have investigated the relationship between processed meat consumption and CRC risk with widely varying results. The unique approach of the present literature review was to include analysis that limited the human studies to those involving only nitrite-containing meat. The majority of these studies reported that nitrite-containing processed meat was associated with increased CRC risk. Nitrite consumption can lead to the formation of N-nitroso compounds (NOC), some of which are carcinogenic. Therefore, this focused perspective based on the current body of evidence links the consumption of meat containing nitrites and CRC risk.

Cancer Mortality by Urbanization and Proximity to the Sea Coast in Campania Region, Southern Italy

Aims and background

The risk for several cancers is higher in urban than in rural areas. The gradient has seldom been studied in southern Europe.

Patients and methods

The geographical pattern of mortality for different cancers and all causes was studied in the Campania Region (about 5.6 million inhabitants), whose largest town is Naples. The key variables were residence in urban/rural and coastal/inland municipalities. Relative risks of death and corresponding 95% confidence intervals by residence were evaluated by means of Poisson log-linear regression models.

Results

Significantly increased mortality rates in urban compared to rural municipalities were found for several cancer causes of death. In particular, in both sexes, excesses in the order of 30-50% were observed for tobacco-related neoplasms (i.e., larynx, lung, and bladder) and cancers of the intestine, liver, brain, multiple myeloma and non-Hodgkin's lymphoma, in addition to all-cancer, and all-cause mortality. In females, specific excesses were also noticed for cancer of the gallbladder, pancreas, breast and uterus (corpus and cervix). Conversely, significantly decreased mortality rates in urban with respect to rural municipalities were observed for cancer of the oral cavity and pharynx in males. Coastal location and degree of urbanization were strongly correlated, thus showing similar associations with most causes of death. However, a significant excess of cancer of the pleura in males was restricted to coastal municipalities.

Conclusions

Anti-smoking campaigns, sanitation improvements, hepatitis B vaccination, and a decrease in obesity emerge as high priorities with respect to cancer control strategies in the Campania Region, particularly in overpopu-lated, underprivileged urban areas.

Consumption of Whole Grains, Refined Cereals, and Legumes and Its Association With Colorectal Cancer Among Jordanians

Background. The role of whole grains, refined cereals, and legumes in preventing or initiating colorectal cancer (CRC) is still uncertain. The aim of this study is to examine the possible association between the consumption of whole grains, refined cereals, and legumes and the risk of developing CRC among Jordanian population. Methods. A validated food frequency questionnaire was used to collect dietary data with regard to intake of whole grains, refined cereals, and legumes. A total of 220 diagnosed CRC participants and 281 CRC-free control participants matched by age, gender, occupation, and marital status were recruited. Logistic regression was used to estimate the odds of developing CRC in relation to the consumption of different types of whole grains, refined cereals, and legumes. Results. The odds ratio (OR) for developing CRC among cases consumed refined wheat bread at all meals was 3.1 compared with controls (95% CI: 1.2-7.9, P_-Trend = 0.001); whereas the OR associated with whole wheat bread was 0.44 (95% CI: 0.22-0.92, P_-Trend = 0.001). The statistical evaluation for daily consumption of rice suggested a direct association with the risk of developing CRC, OR = 3.0 (95% CI: 0.27-33.4, P_-Trend = 0.020). Weekly consumption of macaroni was associated with CRC with OR of 2.4 (95% CI: 1.1-5.3, P_-Trend = 0.001). The consumption of corn, bulgur, lentils, and peas suggested a protective trend, although the trend was not statistically significant. Conclusion. This study provides additional indicators of the protective role of whole grains and suggests a direct association between consumption of refined grains and higher possibility for developing CRC.

High consumption of vegetable and fruit colour groups is inversely associated with the risk of colorectal cancer: a case-control study

The colour of the edible portion of vegetables and fruit reflects the presence of specific micronutrients and phytochemicals. No existing studies have examined the relationship between the intake of vegetable and fruit colour groups and the risk of colorectal cancer. The present study, therefore, aimed to investigate these associations in a Chinese population. A case-control study was conducted between July 2010 and July 2014 in Guangzhou, China, in which 1057 consecutively recruited cases of colorectal cancer were frequency-matched to 1057 controls by age (5-year interval), sex and residence (rural/urban). A validated FFQ was used to collect dietary information during face-to-face interviews. Vegetables and fruit were classified into four groups according to the colour of their primarily edible parts: green; orange/yellow; red/purple; white. Unconditional logistic regression models were used to estimate the OR and 95 % CI. A higher consumption of orange/yellow, red/purple and white vegetables and fruit was inversely associated with the risk of colorectal cancer, with adjusted OR of 0·16 (95 % CI 0·12, 0·22) for orange/yellow, 0·23 (95 % CI 0·17, 0·31) for red/purple and 0·53 (95 % CI 0·40, 0·70) for white vegetables and fruit when the highest and lowest quartiles were compared. Total vegetable intake and total fruit intake have also been found to be inversely associated with colorectal cancer risk. However, the intake of green vegetable and fruit was not associated with colorectal cancer risk. The results of the present study, therefore, suggest that a greater intake of orange/yellow, red/purple and white vegetables and fruit is inversely associated with the risk of colorectal cancer.

Egg consumption and risk of GI neoplasms: dose-response meta-analysis and systematic review

PURPOSE

Previous epidemiological studies on egg consumption and the risk of gastrointestinal (GI) neoplasms suggest a positive association; however, data are limited and the evidence remains controversial. This study aims to investigate and quantify the potential dose-response relationship with an evaluation of cancer site-specific differences.

METHODS

Relevant studies were identified after the literature search via electronic databases until January 2014. Subgroup analysis for serving portions was performed using two standardized classification methods: (1) less than 3, or 3 or more eggs per week; (2) less than 3, 3-5, or more than 5 eggs per week. Method two excludes studies that only reported consumption frequency. Pooled adjusted odds ratios (ORs) comparing highest and lowest categories of dietary pattern scores were calculated using a random-effects model.

RESULTS

Thirty-seven case-control and seven cohort studies were included for meta-analysis, which contained a total of 424,867 participants and 18,852 GI neoplasm cases. The combined odds ratio (OR) was calculated to 1.15 (95% CI 1.09-1.22; p value heterogeneity <0.001), showing only a slight increase in risk. The correlation was stronger for colon cancers 1.29 (95% CI 1.14-1.46; p value heterogeneity <0.22). Dose-response analysis revealed similar results with stratification methods, and the ORs for an intake of <3 and ≥3 eggs per week were 1.14 (95% CI 1.07-1.22; p value heterogeneity = 0.38) and 1.25 (95% CI 1.14-1.38; p value heterogeneity = 0.25), respectively. With method 2, the ORs for an intake of <3, 3-5, and >5 eggs per week were 1.13 (95% CI 1.06-1.21; p value heterogeneity = 0.25), 1.14 (95% CI 1.01-1.29; p value heterogeneity = 0.06), and 1.19 (95% CI 1.01-1.39; p value heterogeneity <0.001), respectively.

CONCLUSION

This study provides evidence that egg consumption is associated with a positive dose-response association with the development of GI neoplasms.

Cruciferous vegetables and risk of colorectal neoplasms: a systematic review and meta-analysis

Evidence shows cruciferous vegetables exhibit chemoprotective properties, commonly attributed to their rich source of isothiocyanates. However, epidemiological data examining the association between cruciferous vegetable intake and colorectal neoplasms have been inconclusive. This meta-analysis examines the epidemiological evidence to characterize the association between cruciferous vegetable intake and risk of developing colorectal neoplasms. Thirty-three articles were included in the meta-analysis after a literature search of electronic databases. Subgroup analysis for individual cruciferae types (n = 8 studies) and GST polymorphism (n = 8 studies) were performed. Pooled adjusted odds ratios (ORs) comparing highest and lowest categories of dietary pattern scores were calculated. Results show a statistically significant inverse association between cruciferous vegetable intake and colon cancer [OR = 0.84; 95% confidence interval (CI): 0.72-0.98; P value heterogeneity < 0.001]. Broccoli in particular exhibited protective benefits against colorectal (CRC) neoplasms (OR = 0.80; 95% CI: 0.65-0.99; P value heterogeneity = 0.02). Stratification by GST genotype reveals that the GSTT1 null genotype confers a reduction in CRC risk (OR = 0.78; 95% CI: 0.64-0.95; P value heterogeneity = 0.32). This study provides support to the hypothesis that cruciferous vegetable intake protects against cancer of the colon. This study also demonstrates the significance of gene-diet interactions and the importance of assessing individual cruciferous vegetables.

Diet and supplements and their impact on colorectal cancer

BACKGROUND

Colorectal cancer is the third commonest cancer and the third leading cause of cancer death among men and women. It has been proposed that dietary factors are responsible for 70-90% of colorectal cancer and diet optimization may prevent most cases.

AIM

To evaluate the role of dietary components and supplements in colorectal cancer.

METHODS

Bibliographical searches were performed in Pubmed for the terms "diet and colorectal cancer", "diet and colon cancer", "diet and rectal cancer", "nutrition and colorectal cancer", "probiotics and colorectal cancer", "prebiotics and colorectal cancer", "alcohol and cancer" and "colorectal cancer epidemiology".

RESULTS

Consumption of processed or red meat, especially when cooked at high temperatures may be associated with increased risk of colorectal cancer. The evidence for dietary fibre is unclear but foods that contain high amounts of fibre are usually rich in polyphenols which have been shown to alter molecular processes that can encourage colorectal carcinogenesis. Meta-analyses provide evidence on the benefits of circulating, diet-derived and supplemented, vitamin D and Calcium. We also found that diets rich in Folate may prevent colorectal carcinoma. The evidence on dietary micronutrients such as Zinc and Selenium in association with colorectal cancer is not conclusive. It has been suggested that there may be a direct association between alcohol intake and colorectal cancer. In vitro and in vivo studies have highlighted a possible protective role of prebiotics and probiotics.

CONCLUSIONS

The lack of randomized trials and the presence of confounding factors including smoking, physical activity, obesity and diabetes may often yield inconclusive results. Carefully designed randomized trials are recommended.

Cruciferous vegetables intake and the risk of colorectal cancer: a meta-analysis of observational studies

BACKGROUND

Epidemiological studies have reported inconsistent associations between cruciferous vegetable (CV) intake and colorectal cancer (CRC) risk. To our knowledge, a comprehensive and quantitative assessment of the association between CV intake and CRC has not been reported.

METHODS

Relevant articles were identified by searching MEDLINE. We pooled the relative risks (RR) from individual studies using a random-effect model and carried out heterogeneity and publication bias analyses.

RESULTS

Twenty-four case-control and 11 prospective studies were included in our analysis. When all studies were pooled, we yielded a significantly inverse association between CV (RR: 0.82; 95% confidence interval 0.75-0.90) intake and CRC risk. Specific analysis for cabbage and broccoli yielded similar result. When separately analyzed, case-control studies of CV intake yield similar results, and the results from the prospective studies showed borderline statistical significance. Moreover, significant inverse associations were also observed in colon cancer and its distal subsite both among prospective and case-control studies.

CONCLUSIONS

Findings from this meta-analysis provide evidence that high intake of CV was inversely associated with the risk of CRC and colon cancer in humans. Further analysis on other specific CV, food preparation methods, stratified results by anatomic cancer site, and subsite of colon cancer should be extended in future study.

Coffee consumption and risk of colorectal cancer: a meta-analysis of observational studies

Objective

Separate meta-analyses based on case–control and cohort studies have reported different results on the relationship between coffee consumption and colorectal cancer risk. To clarify the effect of coffee intake on colorectal cancer risk, we performed a meta-analysis based on both case–control and cohort studies.

Design

Review study.

Setting

We identified case–control and cohort studies related to coffee consumption and colorectal cancer risk listed on MEDLINE, the Cochrane Controlled Trials Register, EMBASE, Science Citation Index and PubMed (until May 2011).

Subjects

Research literature on the relationship between coffee consumption and colorectal cancer risk.

Results

Twenty-five case–control (15 522 cases) and sixteen cohort studies (10 443 cases) were included in the meta-analysis. Comparing the highest v. the lowest/non category of coffee consumption, the combined results from case–control studies showed a significant relationship with colorectal cancer (OR = 0·85, 95 % CI 0·75, 0·97) and colon cancer (OR = 0·79, 95 % CI 0·67, 0·95), but not rectal cancer (OR = 0·95, 95 % CI 0·79, 1·15). For cohort studies, there was a slight suggestion of an inverse association with colorectal cancer (relative ratio = 0·94; 95 % CI 0·88, 1·01) and colon cancer (OR = 0·93, 95 % CI 0·86, 1·01), rather than rectal cancer (OR = 0·98, 95 % CI 0·88, 1·09). In subgroup analyses using case–control studies, significant inverse associations were found in females for colorectal cancer and in Europe for colorectal and colon cancer, while the subgroup analyses of cohort studies found that coffee drinks substantially decreased risk of colon cancer only in Asian women.

Conclusions

Results from case–control studies suggest coffee consumption can significantly decrease the risks of colorectal cancer and colon cancer, especially in Europe and for females.

Fish consumption and colorectal cancer risk in humans: a systematic review and meta-analysis

BACKGROUND

Fish consumption may protect against colorectal cancer, but results from observational studies are inconsistent; therefore, a systematic review with a meta-analysis was conducted.

METHODS

Relevant studies were identified by a search of MEDLINE and EMBASE databases to May 2011, with no restrictions. Reference lists from retrieved articles also were reviewed. Studies that reported odds ratio (OR) or relative risk estimates with 95% confidence intervals (CIs) for the association between the consumption of fish and the risk of colorectal, colon, or rectal cancer were included. Two authors independently extracted data and assessed study quality. The risk estimate (hazard ratio, relative risk, or OR) of the highest and lowest reported categories of fish intake were extracted from each study and analyzed using a random-effects model.

RESULTS

Twenty-two prospective cohort and 19 case-control studies on fish consumption and colorectal cancer risk met the inclusion criteria and were included in the meta-analysis. Our analysis found that fish consumption decreased the risk of colorectal cancer by 12% (summary OR, 0.88; 95% CI, 0.80-0.95). The pooled ORs of colorectal cancer for the highest versus lowest fish consumption in case-control studies and cohort studies were 0.83 (95% CI, 0.72-0.95) and 0.93 (95% CI, 0.86-1.01), respectively. There was heterogeneity among case-control studies (P<.001) but not among cohort studies. A significant inverse association was found between fish intake and rectal cancer (summary OR, 0.79; 95% CI, 0.65-0.97), and there was a modest trend seen between fish consumption and colon cancer (summary OR, 0.96; 95% CI, 0.81-1.14). This study had no publication bias.

CONCLUSION

Our findings from this meta-analysis suggest that fish consumption is inversely associated with colorectal cancer.

Update on the relationship of fish intake with prostate, breast, and colorectal cancers

A systematic review of prospective cohort and case-control studies investigating relationships between the intake of fish and incidence of prostate, breast, or colorectal cancers was conducted. A total of 106 studies fulfilled the requirements stated in the "Search strategy and selection criteria." Among 273 estimates of association reported by these studies, 53 indicated decreased risk while 12 indicated increased risk associated with fish intake. The hypothesis linking fish consumption and low cancer incidence appears to be supported by little epidemiological data. However, there are several factors that may mask potential protective associations with fish intake. The type and the amount of fish eaten, the cooking method, the stage of the cancer and, amongst women, menopausal status may all be important factors that relate to whether fish is protective or not. Future epidemiologic studies with a clearer assessment of these factors are needed to know more about the effects of fish consumption on cancer risk. Therefore, until there are better measures of dietary exposure or biomarkers to correlate self-report, no conclusion can be drawn regarding the recommendation for increasing fish consumption in general to reduce the risk of developing the most common cancers in Western societies.

Foods and food groups associated with the incidence of colorectal polyps: the Adventist Health Study

Colorectal cancer (CRC) is a leading cause of cancer death in the United States. The majority of CRC arise in adenomatous polyps and 25-35% of colon adenoma risk could be avoidable by modifying diet and lifestyle habits. We assessed the association between diet and the risk of self-reported physician-diagnosed colorectal polyps among 2,818 subjects who had undergone colonoscopy. Subjects participated in 2 cohort studies: the AHS-1 in 1976 and the AHS-2 from 2002-2005. Multivariate logistic regression analysis was used to estimate the period risk of incident cases of polyps; 441 cases of colorectal polyps were identified. Multivariate analysis adjusted by age, sex, body mass index, and education showed a protective association with higher frequency of consumption of cooked green vegetables (OR 1 time/d vs. <5/wk = 0.76, 95% CI = 0.59-0.97) and dried fruit (OR 3+ times/wk vs. <1 time/wk = 0.76, 95%CI = 0.58-0.99). Consumption of legumes at least 3 times/wk reduced the risk by 33% after adjusting for meat intake. Consumption of brown rice at least 1 time/wk reduced the risk by 40%. These associations showed a dose-response effect. High frequency of consumption of cooked green vegetables, dried fruit, legumes, and brown rice was associated with a decreased risk of colorectal polyps.

Coffee consumption and risk of colorectal cancer: a meta-analysis of case-control studies

A meta-analysis of case-control studies on coffee consumption and colorectal cancer risk was conducted. Twenty-four eligible studies published before May 2010 were identified, including a total of 14,846 cases of colorectal, colon or rectal cancer. Compared to non/occasional drinkers, the odds ratios (OR) for drinkers were 0.83 (95% CI 0.73-0.95) for colorectal, 0.93 (95% CI 0.81-1.07) for colon and 0.98 (95% CI 0.85-1.13) for rectal cancer, with significant heterogeneity among studies; the corresponding ORs for the increment of 1 cup/day were 0.94 (95% CI 0.91-0.98), 0.95 (95% CI 0.92-0.98), and 0.97 (95% CI 0.95-0.99). For the highest coffee drinkers, the ORs were 0.70 (95% CI 0.60-0.81) for colorectal cancer, 0.75 (95% CI 0.64-0.88) for colon cancer and 0.87 (95% CI 0.75-1.00) for rectal cancer, when compared to non/low drinkers. The results of this meta-analysis of case-control studies suggest a moderate favorable effect of coffee consumption on colorectal cancer risk. The reduced risk was consistent across study design (hospital vs. population based), geographic area, and various confounding factors considered. It may reflect a real protection but also partly or largely be due to reverse causation, i.e. decreased coffee consumption among cases following the onset of bowel symptoms.

Risk of colon cancer and coffee, tea, and sugar-sweetened soft drink intake: pooled analysis of prospective cohort studies

BACKGROUND

The relationships between coffee, tea, and sugar-sweetened carbonated soft drink consumption and colon cancer risk remain unresolved.

METHODS

We investigated prospectively the association between coffee, tea, and sugar-sweetened carbonated soft drink consumption and colon cancer risk in a pooled analysis of primary data from 13 cohort studies. Among 731 441 participants followed for up to 6-20 years, 5604 incident colon cancer case patients were identified. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models and then pooled using a random-effects model. All statistical tests were two-sided.

RESULTS

Compared with nonconsumers, the pooled multivariable relative risks were 1.07 (95% CI = 0.89 to 1.30, P(trend) = .68) for coffee consumption greater than 1400 g/d (about six 8-oz cups) and 1.28 (95% CI = 1.02 to 1.61, P(trend) = .01) for tea consumption greater than 900 g/d (about four 8-oz cups). For sugar-sweetened carbonated soft drink consumption, the pooled multivariable relative risk comparing consumption greater than 550 g/d (about 18 oz) to nonconsumers was 0.94 (95% CI = 0.66 to 1.32, P(trend) = .91). No statistically significant between-studies heterogeneity was observed for the highest category of each beverage consumed (P > .20). The observed associations did not differ by sex, smoking status, alcohol consumption, body mass index, physical activity, or tumor site (P > .05).

CONCLUSIONS

Drinking coffee or sugar-sweetened carbonated soft drinks was not associated with colon cancer risk. However, a modest positive association with higher tea consumption is possible and requires further study.

Primary prevention of colorectal cancer

Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.

Glucosinolates in Brassica vegetables: the influence of the food supply chain on intake, bioavailability and human health

Glucosinolates (GLSs) are found in Brassica vegetables. Examples of these sources include cabbage, Brussels sprouts, broccoli, cauliflower and various root vegetables (e.g. radish and turnip). A number of epidemiological studies have identified an inverse association between consumption of these vegetables and the risk of colon and rectal cancer. Animal studies have shown changes in enzyme activities and DNA damage resulting from consumption of Brassica vegetables or isothiocyanates, the breakdown products (BDP) of GLSs in the body. Mechanistic studies have begun to identify the ways in which the compounds may exert their protective action but the relevance of these studies to protective effects in the human alimentary tract is as yet unproven. In vitro studies with a number of specific isothiocyanates have suggested mechanisms that might be the basis of their chemoprotective effects. The concentration and composition of the GLSs in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, the effects of various factors in the supply chain of Brassica vegetables including breeding, cultivation, storage and processing on intake and bioavailability of GLSs are extensively discussed in this paper.

A 50-year review of colorectal cancer in African Americans: implications for prevention and treatment

BACKGROUND

African-Americans (AA) have the highest rate of colorectal cancer (CRC) incidence and mortality in the US. CRC in AA is more advanced and right-sided. Although screening has been shown to reduce mortality from CRC in the general US population, AA continue to experience a disproportionately higher CRC death compared to other ethnic groups. This study aimed at assessing the trend of CRC in AA, focusing on the changing pattern of in situ tumors in this ethnic group and how observed trends may guide current and future preventive and treatment strategies.

MATERIALS AND METHODS

All pathologic reports from 1959 to 2006 in Howard University Hospital (n = 150,000) were reviewed manually. The pathology reports showing colorectal cancer were carefully reviewed and selected by a GI pathologist. Intraepithelial or intramucosal carcinomas were diagnosed as in situ carcinoma. Reviewed pathological information were entered into Microsoft Excel and checked for duplication and missing data. Differences in situ and advanced cancer by sex, histology, location, and years of diagnosis were assessed by Chi-square test.

RESULTS

A total of 1,753 CRC cases were diagnosed in this period. About 56% of the cases were female and 51% of the tumors were left-sided. Mean (SD) age was 66 (13) years. The frequency of in situ tumor was 5.8% in this period. There was no statistically significant difference between in situ and advance tumor by age, sex, and tumor location. The rate of in situ tumor peaked in the 1990s at 8.5% (P = 0.0001). We observed a decade-to-decade increasing rate of right-sided tumors, which started at 36% in the period 1959-1970 and peaked in the period of 2001-2006 at 60% (P = 0.0001).

CONCLUSIONS

The recent increasing number of advanced and right-sided tumor in our study is concordant with SEER data and has great importance in developing CRC prevention and treatment strategies for AA population.

A case-control study on diet and colorectal cancer from Mumbai, India

Colorectal cancer is more common in the western countries. Studies have reported on risk factors for colorectal cancer across the globe but no study results are reported yet from India. This is the first hospital-based case-control study on colorectal cancer from India. This study conducted at Tata Memorial hospital, Mumbai, India, included 203 cases of colorectal cancer and 1628 hospital controls. Data was collected on chewing, smoking, alcohol habits and dietary habits. The results indicated no significant excess risk for chewers, smokers and alcohol drinkers compared to those without the habits. However some significant findings emerged regarding the dietary habits. Cabbage-eaters had a 50% reduction in risk among both the sexes, compared to those who did not eat cabbage. Sprout eaters also had an 30-50% reduction in risk. There was an enhanced 1.6-fold risk among men who ate 'dry-fish' compared to those who did not eat dry-fish (OR=1.6; CI: 1.0, 2.6). Among women, meat-eaters had a 2.4-fold excess risk than non-meat-eaters. Likewise for fresh-fish eaters, there was a 40-70% reduction in risk compared to those who did not eat fresh-fish. Dark-green-leafy-vegetables and 'other vegetables' did not show any protective effect for colorectal cancer in this study.

A 22-year prospective study of fish, n-3 fatty acid intake, and colorectal cancer risk in men

BACKGROUND

Fish is the main dietary source of long-chain n-3 fatty acids, which have been suggested to play a protective role in colorectal cancer development in laboratory and animal studies. Human studies have not shown consistent results. We examined the association between intakes of fish and n-3 fatty acids from fish and colorectal cancer risk in men enrolled in the Physicians' Health Study.

METHODS

The Physicians' Health Study began as a randomized trial to examine the effect of aspirin and beta-carotene supplementation on cancer and cardiovascular disease. Fish intake was assessed at the 12-month follow-up with an abbreviated food-frequency questionnaire. Cox proportional hazards models were used to estimate multivariate relative risks for colorectal cancer for the categories of fish intake and quartiles of n-3 fatty acid intake.

RESULTS

During 22 years of follow-up, 500 men had a confirmed diagnosis of colorectal cancer. Fish intake was inversely associated with colorectal cancer risk [multivariate relative risk (95% confidence interval) for highest versus lowest category, 0.63 (0.42-0.95); P trend = 0.02] [corrected] The inverse association was observed for both colon and rectal cancers. Our findings for n-3 fatty acids were similar to those for fish; the multivariate relative risk (95% confidence interval) of total colorectal cancer for the highest versus lowest quartile of n-3 fatty acids was 0.74 (0.57-0.95; P trend = 0.01).

CONCLUSIONS

Our results from this long-term prospective study suggest that intakes of fish and long-chain n-3 fatty acids from fish may decrease the risk for colorectal cancer.

The effect of lactose maldigestion on the relationship between dairy food intake and colorectal cancer: a systematic review

Dairy food consumption has been inconsistently shown to protect against colorectal cancer (CRC) in case-based studies, and no clear benefits against recurrent colonic polyps (CRP) have been reported. Based on population-based studies we have hypothesized that dairy food intake may have anti-CRC effects at both low intake lactase non-persistent (LNP) populations and at high intake lactase persistent (LP) subjects. We separately analyse existing case-based studies and divide origins into high LNP (>or= 80% LNP prevalence), low LNP (prevalence <or= 20%) and mid LNP countries (21-79% prevalence), which coincide with low, high, and mid quantity dairy food intake regions, respectively. Odds ratios and relative risks (RR) of highest versus lowest dairy intake within each group are analyzed together for assessment of protection against CRC and CRP. Eighty studies met stipulated criteria. Thirteen analyzed the effect on recurrent polyps. Forest plots from 2 regions, high LNP (low dairy food intake) RR = 0.84 [95% confidence interval (CI) = 0.73-0.97) and low LNP (high dairy food intake) RR = 0.80 (95% CI = 0.73-0.88) demonstrated significant protection against CRC. In mixed LNP/LP populations (mid dairy food intake) nonsignificant protection was found RR = 0.92 (95% CI = 0.79-1.06). Similar regional analysis for CRP failed to show significant protective effect in any region. This meta-analysis supports that the highest level of dairy food consumption protects subjects in both high and low LNP regions but not in areas with significant mixed LNP/LP populations. In both groups, dairy foods had no effect on polyp formation, suggesting it may only protect against CRC at late stages of promotion. These results raise the possibility that LNP/LP status may be partly responsible for the discrepant results with respect to the relationship between dairy food consumption and CRC.

Fruit and vegetable consumption and risk of colorectal cancer in Japan: The Miyagi Cohort Study

Objective

Adequate fruit and vegetable intake has been suggested to protect against colorectal cancer. However, several recent prospective studies have reported no association. We therefore examined the association between fruit and vegetable intakes and the risk of colorectal cancer in a prospective cohort study in Japan.

Design

Between June and August 1990, 47 605 Japanese men and women completed a self-administered questionnaire, including a food-frequency questionnaire. We divided the subjects into quartiles based on their self-reported fruit and vegetable consumption. There were 165 colon cancer and 110 rectal cancer incidences identified during 7 years of follow-up, to the end of December 1997. We used Cox proportional hazards models to estimate the relative risk (RR) of developing colorectal cancer according to the level of fruit and vegetable consumption, applying adjustments for potential confounders.

Results

No statistically significant association was observed between fruit and vegetable consumption and the risk of colorectal cancer. The multivariate RR of colon cancer in the highest quartile of fruit and vegetable intake compared with the lowest was 1.13 (95% confidence interval (CI) 0.73–1.75), the RR for vegetables alone was 1.24 (95% CI 0.79–1.95) and that for fruit alone was 1.45 (95% CI 0.85–2.47). The corresponding multivariate RRs for rectal cancer were 1.12 (95% CI 0.67–1.89), 1.14 (95% CI 0.67–1.93) and 1.41 (95% CI 0.73–2.73).

Conclusions

We found no association between the consumption of fruit and vegetables and the risk of colorectal cancer among the Japanese population.

Dietary Fiber Intake: Assessing the Degree of Agreement between Food Frequency Questionnaires and 4-Day Food Records

OBJECTIVE

To assess the degree of agreement (comparability) between dietary fiber intakes reported on a food frequency questionnaire (FFQ) with 4-day food records (4DFR) and determine whether demographic, behavioral and biological factors influence comparability.

METHODS

At baseline and year one, all participants in the Polyp Prevention Trial (PPT), a multi-center randomized, clinical trial of a low-fat, high fiber, high fruit/vegetable eating plan and recurrence of large bowel adenomatous polyps were instructed in dietary assessment and completed a 106-item FFQ and 4DFR that trained nutritionists reviewed. A random sub-cohort of participants (n = 399) was selected from the intervention and control arms of the PPT for analysis of both FFQ and 4DFR.

RESULTS

Baseline crude and energy-adjusted fiber intakes were significantly higher in the 4DFR than the FFQ (P = 0.001). Using Bland-Altman statistics, the mean difference (FFQ-4DFR) was -0.11 g/MJ; while the limits of agreement were -1.45, 1.23 g/MJ. The mean fiber difference increased with increasing average intake (FFQ + 4DFR)/2, (P = 0.004) for men, but not women (P = 0.10), suggesting that fiber intake was under-estimated in the FFQ, relative to the 4-DFR, for men with low fiber intakes and over-estimated for men with high intakes. Smoking and gender significantly influenced the average intake at baseline, whereas other demographic and behavioral factors did not. Education was significantly associated with average difference in fiber intake at baseline, but not at year 1.

CONCLUSIONS

This study of clinical trial volunteers revealed differences in the ability to comparably report fiber intake across tools by gender, smoking, and education, however participants' repeated training in dietary assessment improved comparability in reporting over time.

High dry bean intake and reduced risk of advanced colorectal adenoma recurrence among participants in the polyp prevention trial

Adequate fruit and vegetable intake was suggested to protect against colorectal cancer and colorectal adenomas; however, several recent prospective studies reported no association. We examined the association between fruits and vegetables and adenomatous polyp recurrence in the Polyp Prevention Trial (PPT). The PPT was a low-fat, high-fiber, high-fruit, and vegetable dietary intervention trial of adenoma recurrence, in which there were no differences in the rate of adenoma recurrence in participants in the intervention and control arms of the trial. In this analysis of the entire PPT trial-based cohort, multiple logistic regression analysis was used to estimate the odds ratio (OR) of advanced and nonadvanced adenoma recurrence within quartiles of baseline and change (baseline minus the mean over 3 y) in fruit and vegetable intake, after adjustment for age, total energyy intake, use of nonsteroidal anti-inflammatory drugs, BMI, and gender. There were no significant associations between nonadvanced adenoma recurrence and overall change in fruit and vegetable consumption; however, those in the highest quartile of change in dry bean intake (greatest increase) compared with those in the lowest had a significantly reduced OR for advanced adenoma recurrence (OR = 0.35; 95% CI, 0.18-0.69; P for trend = 0.001). The median in the highest quartile of change in dry bean intake was 370% higher than the baseline intake. The PPT trial-based cohort provides evidence that dry beans may be inversely associated with advanced adenoma recurrence.

Green tea, black tea and colorectal cancer risk: a meta-analysis of epidemiologic studies

Experimental studies have supported tea as a chemopreventive agent for colorectal cancer. No quantitative summary of the epidemiologic evidence on tea and colorectal cancer risk has ever been performed. The current meta-analysis included 25 papers conducted in 11 countries across three continents (North America, Asia and Europe). Summary odds ratios (ORs) for highest versus non/lowest tea consumption levels were calculated based on fixed and random effects models. The meta-regression and stratified methods were used to examine heterogeneity across studies. For green tea, the combined results from eight studies indicated a reduced risk of colorectal cancer with intake [summary OR = 0.82, 95% confidence interval (CI) = 0.69-0.98]. The protective effect is mainly found among the three case-control studies of colon cancer (summary OR = 0.74, 95% CI = 0.60-0.93). Results from studies of rectal cancer irrespective of study design (case-control versus cohort) (summary OR = 0.99, 95% CI = 0.71-1.37) and cohort studies of colon cancer (summary OR = 0.99, 95% CI = 0.79-1.24) were compatible with the null hypothesis. For black tea, the summary OR derived from 20 studies was 0.99 (95% CI = 0.87-1.13). There is wide divergence in results across the 20 individual studies; formal tests for homogeneity across studies revealed statistically significant differences in findings across all studies (P < 0.001), amongst the 7 cohort studies (P = 0.002), and amongst the 13 case-control studies (P < 0.001). Despite the strong evidence from in vitro and non-human in vivo studies in support of green and black tea as potential chemopreventive agents against colorectal cancer, available epidemiologic data are insufficient to conclude that either tea type may protect against colorectal cancer in humans.

Fiber, sex, and colorectal adenoma: results of a pooled analysis

BACKGROUND

Evidence for an association between dietary fiber and colorectal neoplasia has been equivocal, and some data suggest that there may be sex differences in response to fiber.

OBJECTIVE

We sought to determine whether fiber affects colorectal adenoma recurrence differently in men and women by combining the study populations of 2 large clinical intervention trials: the Wheat Bran Fiber Trial and the Polyp Prevention Trial.

DESIGN

Data from 3209 participants combined from 2 trials were analyzed with logistic regression models to examine the effect of a dietary intervention on colorectal adenoma recurrence in the pooled population as a whole and by sex.

RESULTS

The adjusted odds ratio for adenoma recurrence for those in the intervention group of either the Wheat Bran Fiber Trial or the Polyp Prevention Trial was 0.91 (95% CI: 0.78, 1.06). For men, the intervention was associated with statistically significantly reduced odds of recurrence with an odds ratio of 0.81 (95% CI: 0.67, 0.98); for women, no significant association was observed. Using a likelihood-ratio test, we found a statistically significant interaction between intervention group and sex (P = 0.03).

CONCLUSION

The results of the current analyses indicate that men may experience more benefit from dietary fiber than do women and may help to explain some of the discrepant results reported in the literature.

Peanut consumption and reduced risk of colorectal cancer in women: A prospective study in Taiwan

AIM: To examine whether peanut consumption is associated with a reduced risk of colorectal cancer in a prospective cohort with a 10-year follow-up.

METHODS: In 1990-1992, residents (12 026 men and 11 917 women aged 30 to 65 years) in 7 townships, Taiwan, were interviewed and recruited into a cancer-screening cohort and annually followed up. Colorectal cancer cases in this cohort were identified from cancer registry and death certificates. Incidence rates of this disease by the end of 2001 were calculated by gender for the primary study variable and covariates. The dietary intake was assessed by means of weekly food frequency measures, including frequently consumed food groups and folk dishes including sweet potato, bean products, peanut products, pickled foodstuffs, nitrated or smoked foodstuffs.

RESULTS: During the study period, 107 new colorectal cancer cases (68 men and 39 women) were confirmed. The multivariate Cox’s proportional hazard model showed that the relative risk (RR) of peanut consumption was 0.73 [95% confidence interval (CI) = 0.44-1.21] for men and 0.42 (95% CI = 0.21-0.84) for women. However, frequent intake of pickled foodstuffs was harmful for women (RR = 2.15, 95% CI = 0.99-4.65). The risk of colorectal cancer was also elevated among cigarette smokers but not significant (P < 0.05).

CONCLUSION: This study suggests that frequent intake of peanut and its products may reduce colorectal cancer risk in women, demonstrating the anti-proliferating effect of peanut intake.

Fish, long-chain n-3 polyunsaturated fatty acids, and risk of colorectal cancer in middle-aged Japanese: the JPHC study

Although long-chain n-3 polyunsaturated fatty acids (Ln-3 PUFA), which are abundant in fish, have shown protective effects on colorectal cancer in laboratory studies, epidemiological studies to date have not been consistent. We evaluated the relationship of consumption of fish and Ln-3 PUFA to the colon and rectal cancer risk in the two cohorts of the Japan Public Health Center-based prospective study of 42,525 men and 46,133 women. Dietary and other exposure data were obtained between 1990 and 1994. Through December 1999, 705 cases of colon and rectal cancer were documented. When data from the two cohorts were pooled, multivariable relative risks (RRs) for the highest quartile compared with the lowest quartile of fish consumption were 1.07 (95% confidence interval, CI = 0.77-1.48) for colon cancer and 0.95 (95% CI = 0.63-1.43) for rectal cancer with no dose-risk trend. RRs for the highest quartile compared with the lowest quartile of eicosapentaenoic acid consumption were 1.05 (95% CI = 0.76-1.46) for colon cancer and 0.91 (95% CI = 0.60-1.38) for rectal cancer with no dose-risk trend. This study does not support the role of fish and Ln-3 PUFA in the etiology of colon and rectal cancer in this population whose fish consumption was high and the variation in Ln-3 PUFA consumption was large.

Dietary Marine n-3 Fatty Acids in Relation to Risk of Distal Colorectal Adenoma in Women

Epidemiologic studies of dietary marine n-3 fatty acids and risk of colorectal cancer have been inconsistent, and their relation to risk of colorectal adenoma has not been evaluated in detail. We examined dietary marine n-3 fatty acids and the ratio of marine n-3 to total n-6 fatty acids (n-3/n-6 ratio) in relation to risk of adenoma of the distal colon or rectum among 34,451 U.S. women who were initially free of colorectal cancer or polyps, who completed a semiquantitative food frequency questionnaire in 1980, and who underwent endoscopy from 1980 to 1998. We documented 1,719 distal colorectal adenoma cases (705 large adenomas, 897 small adenomas, 1,280 distal colon adenomas, and 505 rectal adenomas) during 18 years of follow-up. Neither dietary marine n-3 fatty acids nor n-3/n-6 ratio were associated with risk of total distal colorectal adenoma after adjustment for age and established risk factors [multivariable relative risk (RR) for extreme quintiles of dietary marine n-3 fatty acids = 1.04; 95% confidence interval (95% CI), 0.84-1.27, P(trend) = 0.66; RR for extreme quintiles of n-3/n-6 ratio = 1.02; 95% CI, 0.83-1.25; P(trend) = 0.86]. Similarly, no significant associations were observed separately for distal colon or rectal adenoma. However, higher intake of dietary marine n-3 fatty acids was nonsignificantly but suggestively inversely associated with large adenoma (RR, 0.74; 95% CI, 0.54-1.01; P(trend) = 0.16) but directly associated with small adenoma (RR, 1.36; 95% CI, 1.02-1.81; P(trend) = 0.09). Our findings do not support the hypothesis that a higher intake of marine n-3 fatty acids or a higher n-3/n-6 ratio reduces the risk of distal colorectal adenoma but are suggestive that higher intake may reduce the progression of small adenomas to large adenomas.

Primary prevention of colorectal cancer: lifestyle, nutrition, exercise

The past two decades have provided a vast amount of literature related to the primary prevention of colorectal cancer. Large international variation in colorectal cancer incidence and mortality rates and the prominent increases in the incidence of colorectal cancer in groups that migrated from low- to high-incidence areas provided important evidence that lifestyle factors influence the development of this malignancy. Moreover, there is convincing evidence from epidemiological and experimental studies that dietary intake is an important etiological factor in colorectal neoplasia. Although the precise mechanisms have not been clarified, several lifestyle factors are likely to have a major impact on colorectal cancer development. Physical inactivity and to a lesser extent, excess body weight, are consistent risk factors for colon cancer. Exposure to tobacco products early in life is associated with a higher risk of developing colorectal neoplasia. Diet and nutritional factors are also clearly important. Diets high in red and processed meat increase risk. Excess alcohol consumption, probably in combination with a diet low in some micronutrients such as folate and methionine, appear to increase risk. There is also recent evidence supporting a protective effect of calcium and vitamin D in the etiology of colorectal neoplasia. The relationship between intake of dietary fiber and risk of colon cancer has been studied for three decades but the results are still inconclusive. However, some micronutrients or phytochemicals in fiber-rich foods may be important; folic acid is one such micronutrient that has been shown to protect against the development of colorectal neoplasia and is currently being studied in intervention trials of adenoma recurrence. The overwhelming evidence indicates that primary prevention of colon cancer is feasible. Continued focus on primary prevention of colorectal cancer, in combination with efforts aimed at screening and surveillance, will be vital in attaining the greatest possible progress against this complex, yet highly preventable disease.

Effect of diet, life style, and other environmental/chemopreventive factors on colorectal cancer development, and assessment of the risks

This review presents a comprehensive, evenhanded evaluation of the evidence from experimental, in vitro and human studies associating environmental and therapeutic factors with risk of colorectal cancer. Life styles correlated with the greatest increase in colorectal cancer risk are the ones that typify a diet rich in fat and calories, alcohol drinking and tobacco smoking, and low intake of vegetable, fruits and fibers, referred to as a "western diet," as well as sedentary style (i.e., no- or low-exercise). This kind of life style has also been associated with other chronic diseases (other cancers, obesity, dyslipedemia, diabetes, hypertension cardiovascular, and hypertension). The evidence does not implicated red meat as a risk factor, and fiber has been shown to protect against colorectal adenomas and carcinomas. Calcium, vitamin D, folate, and some antioxidant vitamins and minerals (gamma-tocopherol and selenium) have protective effects, and daily exercise for > or =30 min results in a significant decrease in risk. Estrogen use (hormone replacement therapy) substantially reduces colorectal cancer risk in postmenopausal women. Nonsteroidal anti-inflammatory drugs (e.g., aspirin) in excessive doses is protective, especially in high risk populations, but the side effects of its use and cost incurred due to its continued intake over long periods must be carefully scrutinized before any recommendations are made for the general public.

The epidemiology of tea consumption and colorectal cancer incidence

This manuscript provides a brief synopsis of 30 studies aimed at examining tea consumption as a factor in the incidence of colon and rectal cancers. The 30 papers examine populations in 12 countries and provide data on consumption of both black and green tea. These studies do not provide consistent evidence to support the theory from animal studies and basic research that tea is a potent chemopreventive agent. Details of the studies are presented, and the potential impact of measurement error, publication bias, the form of tea consumed, the appropriateness of the outcomes studied and the adjustment of confounders related to both tea consumption and risk of colorectal cancer or polyps in various countries are explored. In general, the data are not more consistent for green than for black tea. Particularly with green tea, the doses consumed do get into a perceived protective range in a significant subset of the population. A negative association is stronger in observational epidemiologic studies of rectal cancer than in colon cancer. There is no consistent adjustment for important potential confounders of any tea relationship, such as coffee and alcohol consumption and physical activity levels. Finally, the assessment of tea in most of these studies was based on a single question and therefore may have significant measurement error compared with more recent studies specifically aimed at assessing tea consumption.

Epidemiologic evidence of the protective effect of fruit and vegetables on cancer risk

BACKGROUND

Diets rich in fruit and vegetables have been recommended for preventing cancer. The evidence supporting this recommendation is based on observational studies, although results of several prospective studies have cast some doubts on whether fruit and vegetables are associated with cancer risk reduction.

OBJECTIVE

We sought to summarize evidence from case-control and prospective studies on fruit and vegetable intake and cancer risk with a meta-analytic approach.

DESIGN

Published case-control and cohort studies that reported on total vegetable and fruit intake and risk of cancer of several sites were included. Relative risks were estimated by using linear logistic regression models.

RESULTS

Case-control studies overall support a significant reduction in the risks of cancers of the esophagus, lung, stomach, and colorectum associated with both fruit and vegetables; breast cancer is associated with vegetables but not with fruit; and bladder cancer is associated with fruit but not with vegetables. The overall relative risk estimates from cohort studies suggest a protective effect of both fruit and vegetables for most cancer sites considered, but the risk reduction is significant only for cancers of the lung and bladder and only for fruit.

CONCLUSIONS

Prospective studies provide weaker evidence than do case-control studies of the association of fruit and vegetable consumption with reduced cancer risk. The discrepancies may be related to recall and selection biases in case-control studies. In contrast, the association may have been underestimated in prospective studies because of the combined effects of imprecise dietary measurements and limited variability of dietary intakes within each cohort.

Egg Consumption and Mortality From Colon and Rectal Cancers: An Ecological Study

The relation between egg consumption and mortality from colon and rectal cancers remains unclear and was investigated in this study. Colon and rectal cancer mortality data, mostly around 1993-94 and egg consumption data in nine time periods (1964-94) in 34 countries were derived from World Health Organization and Food and Agriculture Organization, respectively. Egg consumption was significantly and positively correlated with mortality from colon and rectal cancers in both sexes in most of the nine time periods. The correlations were generally stronger for colon cancer (r = 0.39 to 0.63 in men and r = 0.33 to 0.65 in women) than for rectal cancer (r = 0.18 to 0.49 in men and r = 0.08 to 0.45 in women). After adjustment for confounding factors, egg consumption was still significantly and positively associated with mortality from colon cancer in the earliest five time periods (1964-84) (P = 0.046 to 0.017 in men and P = 0.034 to 0.014 in women) and rectal cancer in the latest five time periods except for the last time period (1982-91) (P = 0.046 to 0.024 in men and P = 0.045 to 0.026 in women). This study suggested that egg consumption was associated with an increased risk of colon and rectal cancers at the population level

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

Foods associated with precancerous colorectal adenoma, especially those associated with large adenomas, are poorly understood. We compared food intake in polyp-free controls (n = 427) with small adenoma (n = 154) or large adenoma (n = 208) cases in Burgundy (France). Logistic regression models controlled for age, gender, and energy. Consumption of lean meat was associated with a reduced risk of small adenomas [odds ratio (OR) for 4th vs. 1st quartile = 0.3, 95% confidence interval (CI) = 0.2-0.6] and large adenomas (OR = 0.4, 95% CI = 0.3-0.7) compared with controls. There was an increased risk with p t s and meat spread [OR = 2.1, 95% CI = 1.1-3.7 (small adenomas) and OR = 2.6, 95% CI = 1.5-4.4 (large adenomas)], bread [OR = 2.0, 95% CI = 1.1-3.6 (small adenomas) and OR = 2.2, 95% CI = 1.3-3.7 (large adenomas)], and pasta (OR = 1.7, 95% CI = 0.9-3.0 in small adenomas only). Animal fats were associated with an increased risk of large adenomas compared with small adenomas (OR = 2.4, 95% CI = 1.1-5.0), whereas yogurt intake was associated with a lower risk (OR for high vs. no intake = 0.5, 95% CI = 0.3-0.9). These findings suggest that some risk factors that have been found to be associated with cancer, such as refined cereal products and high-fat animal products, also influence early stages of colorectal carcinogenesis.

Fish consumption and colorectal cancer: a case-reference study in Japan

Several clinical studies have suggested that supplementation with fish oils can suppress the proliferation of colorectal mucosa and therefore inhibit the development of colorectal cancer. However, epidemiological evidence concerning fish consumption and risk is inconsistent and limited. To clarify the association between intake of fish and the likelihood of developing colorectal cancer, we conducted a large sample size case-reference study with 928 cases of colon cancer, 622 of rectal cancer and 46886 cancer-free outpatient references aged 40-79 years. The data showed frequent raw/cooked fish intake to be associated with decreased odds ratio (OR) 0.68 with 95% confidence interval (CI) 0.47-0.99 for male colon cancer, especially for males aged over 60 years, smokers and frequent meat eaters. A marginal decrease in the OR (OR 0.58, 95% CI 0.31-1.07) was also detected for female rectal cancer, especially in the regular physical exercise subgroup. However, frequent dried/salted fish intake was found to be associated with increased OR in females younger than 60 years old and alcohol drinkers. Although there is some possible bias in epidemiological studies, the results suggest that frequent raw/cooked fish intake may decrease the risk while dried/salted fish, in contrast, may exert a detrimental effect.

Characterization of meat consumption and risk of colorectal cancer in Cordoba, Argentina

BACKGROUND

The Argentinean food pattern, rich in beef and fats and poor in fibers, may be related to an risk of increased colorectal cancer (CRC). To examine the relation between CRC risk and meat type, we carried out a case-control study in Córdoba, Argentina.

METHODS

We interviewed 287 patients with colorectal adenocarcinomas and 566 control subjects admitted to the largest hospitals in greater Córdoba. Dietary habits were assessed by a food-frequency questionnaire, and different meat types were evaluated. Regression analyses determined the contribution of meat to total energy and macronutrients. Unconditional multiple logistic regression was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Median intake of all meats, predominantly bovine, was high, reaching almost 300 g/d in men. Meats provided approximately 50% of total energy intake and 64% to 67% of total protein. Patients obtained significantly more cholesterol and total lipids from meats than did controls. Consumption of total meat, red meat, and other types of meat were not related to increased risk of CRC. However, an increased risk of CRC was found for those consuming relatively large amounts of cold cuts and sausages (OR, 1.47; CI, 1.02-2.15) and bovine viscera (OR, 1.73; CI, 1.18-2.54). Lean beef was associated with a decreased risk of CRC at the second (OR, 0.64; CI, 0.43-0.94) and third (OR, 0.67; CI, 0.40-0.97) tertiles.

CONCLUSIONS

Red meat produced a different pattern of risk according to its fat content. Further studies should assess the possible role of cooking meat and other non-nutritional components.

Dairy products and colorectal cancer. A review of possible mechanisms and epidemiological evidence

OBJECTIVES

This review provides an overview of the principal hypotheses and epidemiological evidence of the possible links between colorectal cancer and intake of milk and/or dairy products.

METHODS

The first section outlines the main hypotheses about the possible effect of calcium, vitamin D, fats and other milk components. The possible role of acid lactic bacteria in fermented products is also discussed. The second section is a summary of the published epidemiological evidence. The results on milk, cheese and yoghurt are summarized using a meta-analytical approach. The results of studies on calcium and vitamin D are briefly described.

RESULTS

Case-control studies are heterogeneous and, on average, do not provide evidence of association between total intake of total dairy products, milk, cheese or yoghurt and colorectal cancer risk. The average result from cohort studies support the hypothesis of a protective effect of total dairy products (odds ratio (OR): 0.62; 95% confidence interval (CI): 0.52-0.74; P heterogeneity test: 0.93) and for milk (OR: 0.80; 95% CI: 0.68-0.95; P heterogeneity: 0.77). No association was found between cheese (OR: 1.10; 95% CI: 0.88-1.36; P heterogeneity: 0.55) or yoghurt (OR: 1.03; 95% CI: 0.83-1.28; P heterogeneity: 0.69) in cohort studies.

CONCLUSIONS

Cohort studies consistently found a protective effect of total dairy products and milk intake, but the evidence is not supported by case-control studies. No relationship was found with cheese or yoghurt intake. As the number of cohort studies is still limited, their results need to be confirmed by other prospective studies.