Flavonoids and laryngeal cancer risk in Italy

Flavonoids regulate tumor-associated macrophages - From structure-activity relationship to clinical potential (Review)

In recent years, the strategy for tumor therapy has changed from focusing on the direct killing effect of different types of therapeutic agents on cancer cells to the new mainstream of multi-mode and -pathway combined interventions in the microenvironment of the developing tumor. Flavonoids, with unique tricyclic structures, have diverse and extensive immunomodulatory and anti-cancer activities in the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most abundant immunosuppressive cells in the TME. The regulation of macrophages to fight cancer is a promising immunotherapeutic strategy. This study covers the most comprehensive cognition of flavonoids in regulating TAMs so far. Far more than a simple list of studies, we try to dig out evidence of crosstalk at the molecular level between flavonoids and TAMs from literature, in order to discuss the most relevant chemical structure and its possible relationship with the multimodal pharmacological activity, as well as systematically build a structure-activity relationship between flavonoids and TAMs. Additionally, we point out the advantages of the macro-control of flavonoids in the TME and discuss the potential clinical implications as well as areas for future research of flavonoids in regulating TAMs. These results will provide hopeful directions for the research of antitumor drugs, while providing new ideas for the pharmaceutical industry to develop more effective forms of flavonoids.

Flavan-3-ols consumption and cancer risk: A meta-analysis of epidemiologic studies

Although numerous in vitro studies and animal model data have suggested that flavan-3-ols, the most common subclass of flavonoids in the diet, may exert protective effects against cancer, epidemiologic studies have reported inconclusive results for the association between flavan-3-ols intake and cancer risk. Therefore, we conducted this meta-analysis of epidemiologic studies to investigate the preventive effects of flavan-3-ols on various types of cancers. A total of 43 epidemiologic studies, consisting of 25 case-control and 18 prospective cohort studies, were included. A significant inverse association was shown between flavan-3-ols intake and the risk of overall cancer (relative risk (RR) 0.935, 95%CI: 0.891-0.981). When cancer types were separately analyzed, a statistically significant protective effect of flavan-3-ols consumption was observed in rectal cancer (RR 0.838, 95%CI: 0.733-0.958), oropharyngeal and laryngeal cancer (RR 0.759, 95%CI: 0.581-0.993), breast (RR 0.885, 95%CI: 0.790-0.991) in case-control studies and stomach cancer in women (RR 0.633, 95%CI: 0.468-0.858). Our analysis indicates the potential benefits of flavan-3-ols in cancer prevention.

Intake of Individual Flavonoids and Risk of Carcinogenesis: Overview of Epidemiological Evidence

Several epidemiological findings have demonstrated that specific flavonoids can be responsible for reduction of the risk of certain cancer types. However, these results are still rather limited, inconclusive and controversial. Therefore, in this comprehensive review article the findings reported to date about the associations between dietary intake of individual flavonoid compounds and cancer incidence are compiled and analyzed. Also, the possible reasons for inconsistencies are brought forth and discussed. As diet is a potentially modifiable factor in our behavioral choices, further large-scale prospective studies with longer follow-up times, different populations, various doses and exposure timing as well as diverse well-controlled confounders are highly needed to confirm or disprove the current epidemiological knowledge about the role of flavonoids on cancer risk. Regarding the promising data to date, more research on bioavailability, metabolism and biological action mechanisms of these plant secondary metabolites is also encouraged.

Dietary Flavonoid Intake Reduces the Risk of Head and Neck but Not Esophageal or Gastric Cancer in US Men and Women

Background: Flavonoids are bioactive polyphenolic compounds found in fruits, vegetables, and beverages of plant origin. Previous studies have shown that flavonoid intake reduces the risk of certain cancers; however, few studies to date have examined associations of flavonoids with upper gastrointestinal cancers or used prospective cohorts.Objective: Our study examined the association between intake of flavonoids (anthocyanidins, flavan-3-ols, flavanones, flavones, flavonols, and isoflavones) and risk of head and neck, esophageal, and gastric cancers.Methods: The NIH-AARP Diet and Health Study is a prospective cohort study that consists of 469,008 participants. Over a mean 12-y follow-up, 2453 head and neck (including 1078 oral cavity, 424 pharyngeal, and 817 laryngeal), 1165 esophageal (890 adenocarcinoma and 275 squamous cell carcinoma), and 1297 gastric (625 cardia and 672 noncardia) cancer cases were identified. We used Cox proportional hazards regression models to estimate HRs and CIs for the associations between flavonoid intake assessed at study baseline and cancer outcomes. For 56 hypotheses examined, P-trend values were adjusted using the Benjamini-Hochberg (BH) procedure for false discovery rate control.Results: The highest quintile of total flavonoid intake was associated with a 24% lower risk of head and neck cancer (HR: 0.76; 95% CI: 0.66, 0.86; BH-adjusted 95% CI: 0.63, 0.91; P-trend = 0.02) compared with the lowest quintile. Notably, anthocyanidins were associated with a 28% lower risk of head and neck cancer (HR: 0.72; 95% CI: 0.62, 0.82; BH-adjusted 95% CI: 0.59, 0.87; P-trend = 0.0005), and flavanones were associated with a 22% lower risk of head and neck cancer (HR: 0.78; 95% CI: 0.68, 0.89; BH-adjusted 95% CI: 0.64, 0.94; P-trend: 0.02). No associations between flavonoid intake and risk of esophageal or gastric cancers were found.Conclusions: Our results indicate that flavonoid intake is associated with lower head and neck cancer risk. These associations suggest a protective effect of dietary flavonoids on head and neck cancer risk, and thus potential as a risk reduction strategy.

Adherence to the World Cancer Research Fund/American Institute for Cancer Research recommendations and head and neck cancers risk

OBJECTIVES

The World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR) have proposed eight recommendations for cancer prevention, related to body fatness, diet, and physical activity. Our aim is to evaluate the role of adherence to these recommendations on head and neck cancers risk.

MATERIALS AND METHODS

We obtained an overall score including seven of the WCRF/AICR recommendations, and examined its relationship with head and neck cancers risk in two Italian case-control studies including 946 patients with oral cavity and pharyngeal (OCP) cancer and 2492 controls, and 689 patients with laryngeal cancer and 1605 controls.

RESULTS

Higher adherence to WCRF/AICR recommendations was associated to a reduced risk of OCP cancer (odds ratio, OR=0.45, 95% confidence interval, CI: 0.33-0.62 for a score of 4-<5, and OR=0.32, 95% CI: 0.22-0.49 for a score of ⩾5 as compared to <3). The ORs for laryngeal cancer were 0.68 (95% CI: 0.50-0.92) for a score of 3-<4, 0.39 (95% CI: 0.28-0.55) for a score of 4-<5, and 0.24 (95% CI: 0.15-0.38) for a score of ⩾5.

CONCLUSION

Our study indicates that high adherence to the WCRF/AICR recommendations for cancer prevention is associated with a substantially decreased risk of head and neck cancers.

Inflammatory potential of diet and risk of laryngeal cancer in a case-control study from Italy

BACKGROUND

Besides tobacco and alcohol, diet and inflammation have been suggested to be important risk factors for laryngeal cancer. In this study, we examined the role of diet-associated inflammation, as estimated by dietary inflammatory index (DII) scores, in laryngeal cancer in a multicentre case-control study conducted between 1992 and 2000 in Italy.

METHODS

This study included 460 cases with incident, histologically confirmed laryngeal cancer, and 1,088 controls hospitalized for acute non-neoplastic diseases unrelated to tobacco and alcohol consumption. DII scores were computed from a reproducible and valid 78-item food-frequency questionnaire. Logistic regression models controlling for age, sex, study center, education, body mass index, tobacco smoking, alcohol drinking, and non-alcohol energy intake were used to estimate odds ratios (ORs) and the corresponding 95 % confidence intervals (CIs).

RESULTS

Subjects with higher DII scores (i.e., with a more pro-inflammatory diet) had a higher risk of laryngeal cancer. The OR was 3.30 (95 % CI 2.06, 5.28; p for trend <0.0001) for the highest versus the lowest DII quartile. When DII was considered as a continuous variable, the OR was 1.27 (95 % CI 1.15, 1.40) for a one-unit (9 % of the DII range) increase. Stratified analyses produced slightly stronger associations between DII and laryngeal cancer risk among Subjects <60 years old (ORquartile4vs1 = 4.68), overweight subjects (ORQuartile4vs1 = 3.62), and among those with higher education (ORQuartile4vs1 = 3.92). We also observed a strong combined effect of higher DII and tobacco smoking or alcohol consumption on risk of laryngeal cancer. Compared with non-smokers having low DII scores, the OR was 6.64 for smokers with high DII scores. Likewise, compared with non/moderate drinkers with low DII, the OR was 5.82 for heavy drinkers with high DII.

CONCLUSION

These results indicate that a pro-inflammatory diet is associated with increased risk of laryngeal cancer.

Relation of allium vegetables intake with head and neck cancers: evidence from the INHANCE consortium

SCOPE

Only a few studies analyzed the role of allium vegetables with reference to head and neck cancers (HNC), with mixed results. We investigated the potential favorable role of garlic and onion within the International Head and Neck Cancer Epidemiology (INHANCE) Consortium.

METHODS AND RESULTS

We analyzed pooled individual-level data from eight case-control studies, including 4590 cases and 7082 controls. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between garlic and onion intakes and HNC risk. Compared with no or low garlic use, the ORs of HNC were 0.95 (95% CI 0.71-1.27) for intermediate and 0.74 (95% CI 0.55-0.99) for high garlic use (p for trend = 0.02). The ORs of HNC for increasing categories of onion intake were 0.91 (95% CI 0.68-1.21) for >1 to ≤3 portions per week, and 0.83 (95% CI 0.60-1.13) for >3 portions per week (p for trend = 0.02), as compared to <1 portion per week. We found an inverse association between high onion intake and laryngeal cancer risk (OR = 0.69; 95% CI 0.54-0.88), but no significant association for other subsites.

CONCLUSION

The results of this pooled-analysis support a possible moderate inverse association between garlic and onion intake and HNC risk.

Epigenetic activities of flavonoids in the prevention and treatment of cancer

Aberrant epigenetic modifications are described in an increasing number of pathological conditions, including neurodegenerative diseases, cardiovascular diseases, diabetes mellitus type 2, obesity and cancer. The general reversibility of epigenetic changes makes them an attractive and promising target e.g. in the treatment of cancer. Thus, a growing number of epigenetically active compounds are currently tested in clinical trials for their therapeutic potential. Interestingly, many phytochemicals present in plant foods, particularly flavonoids, are suggested to be able to alter epigenetic cellular mechanisms. Flavonoids are natural phenol compounds that form a large group of secondary plant metabolites with interesting biological activities. They can be categorized into six major subclasses, which display diverse properties affecting the two best characterized epigenetic mechanisms: modulation of the DNA methylation status and histone acetylation. High dietary flavonoid intake has strongly been suggested to reduce the risk of numerous cancer entities in a large body of epidemiological studies. Established health-promoting effects of diets rich in fruit and vegetables are faced by efforts to use purified flavonoids as supplements or pharmaceuticals, whereupon data on the latter applications remain controversial. The purpose of this review is to give an overview of current research on flavonoids to further elucidate their potential in cancer prevention and therapy, thereby focusing on their distinct epigenetic activities.

Biotransformation of luteoloside by a newly isolated human intestinal bacterium using UHPLC-Q-TOF/MS

To explore the metabolic pathways and metabolites of luteoloside yielded by the isolated human intestinal bacteria from healthy human feces and characterize the β-d-glucosidase activity of the specific strain which catalyzed the breakdown of luteoloside, a preculture bacterial GAM broth and luteoloside were mixed incubated together for 48h. UHPLC-Q-TOF/MS was used for analysis of the metabolites of luteoloside in the corresponding supernatant fractions from fermentation. Aliquots of the reactive solutions were collected at different times and were measured with a microplate reader at 405nm to evaluate the enzymatic activity. Three metabolites (acetylated luteoloside, luteolin and deoxygenated luteolin) were detected in the fractions isolated from the bacterial samples. The variation of β-d-glucosidase activity inside the bacterium was in coincidence with the changes in luteolin generation or luteoloside degradation in different time periods.

Dietary flavonoid intake and smoking-related cancer risk: a meta-analysis

Purpose

To systematically investigate the effects of dietary flavonoids and flavonoid subclasses on the risk of smoking-related cancer in observational studies.

Methods

Summary estimates and corresponding standard errors were calculated using the multivariate-adjusted odds ratio (OR) or relative risk (RR) and 95% CI of selected studies and weighted by the inverse variance.

Results

A total of 35 studies, including 19 case-controls (9,525 cases and 15,835 controls) and 15 cohort studies (988,082 subjects and 8,161 cases), were retrieved for the meta-analysis. Total dietary flavonoids and most of the flavonoid subclasses were inversely associated with smoking-related cancer risk (OR: 0.82, 95% CI: 0.72-0.93). In subgroup analyses by cancer site, significant associations were observed in aerodigestive tract and lung cancers. Total dietary flavonoid intake was significantly associated with aerodigestive tract cancer risk (OR: 0.67, 95% CI: 0.54-0.83) marginally associated with lung cancer risk (OR: 0.84, 95% CI: 0.71-1.00). Subgroup analyses by smoking status showed significantly different results. The intake of total flavonoids, flavonols, flavones, and flavanones, as well as the flavonols quercetin and kaempferol was significantly associated with decreased risk of smoking-related cancer in smokers, whereas no association was observed in non-smokers, except for flavanones. In meta-analysis for the effect of subclasses of dietary flavonoids by cancer type, aerodigestive tract cancer was inversely associated with most flavonoid subclasses.

Conclusion

The protective effects of flavonoids on smoking-related cancer risk varied across studies, but the overall results indicated that intake of dietary flavonoids, especially flavonols, was inversely associated with smoking-related cancer risk. The protective effects of flavonoids on smoking-related cancer risk were more prominent in smokers.

Regulation, evolution, and functionality of flavonoids in cereal crops

Flavonoids are plant secondary metabolites that contribute to the adaptation of plants to environmental stresses, including resistance to abiotic and biotic stress. Flavonoids are also beneficial for human health and depress the progression of some chronic diseases. The biosynthesis of flavonoids, which belong to a large family of phenolic compounds, is a complex metabolic process with many pathways that produce different metabolites, controlled by key enzymes. There is limited knowledge about the composition, biosynthesis and regulation of flavonoids in cereals. Improved understanding of the accumulation of flavonoids in cereal grains would help to improve human nutrition through these staple foods. The biosynthesis of flavonoids, scope for altering the flavonoid composition in cereal crops and benefits for human nutrition are reviewed here.

Nutrient-based dietary patterns of head and neck squamous cell cancer: a factor analysis in Uruguay

OBJECTIVE

The aim of this study was to investigate the association between nutrient-based dietary patterns and squamous cell cancers of the head and neck.

METHODS

We used a case-control study which included 548 cases and 548 controls. From these participants, we derived 23 nutrients and they were then submitted to a factorability analysis in order to conduct a principal component factor analysis.

RESULTS

We were able to identify four nutrient-derived patterns. The first pattern (meat-based pattern) was positively associated with squamous cell cancer of the head and neck (OR 2.85, 95 % CI 1.81-4.15), whereas the third pattern (fruit-based) was strongly protective (OR 0.43, 95 % CI 0.27-0.63). The other nutrient patterns were also significantly associated with head and neck squamous cell carcinoma with minor ORs.

CONCLUSION

Both patterns suggest that red meat and fruits are major factors in the etiology of head and neck squamous cell cancer, replicating previous studies in the field.

Flavonoids and cancer prevention: a review of the evidence

The objective of this work is to review data from epidemiological and preclinical studies addressing the potential benefits of diets based on flavonoids for cancer prevention. Flavonoids are subdivided into subclasses including flavonols, flavones, flavanones, flavan-3-ols, anthocyanidins, and isoflavones. Epidemiological studies suggest dietary intake of flavonoids may reduce the risk of tumors of the breast, colon, lung, prostate, and pancreas. However, some studies have reported inconclusive or even harmful associations. A major challenge in the interpretation of epidemiological studies is that most of the data originate from case-control studies and retrospective acquisition of flavonoid intake. Differences in agricultural, sociodemographics, and lifestyle factors contribute to the heterogeneity in the intake of flavonoids among populations residing in the United States, Europe, and Asia. Dose and timing of exposure may influence the anticancer response to flavonoid-rich diets. A limited number of intervention trials of flavonoids have documented cancer preventative effects. Proposed anticancer mechanisms for flavonoids are inhibition of proliferation, inflammation, invasion, metastasis, and activation of apoptosis. Prospective studies with larger sample sizes are needed to develop biomarkers of flavonoid intake and effect. Mechanistic studies are needed to ascertain how flavonoid-rich diets influence gene regulation for cancer prevention.

Diet and the risk of head and neck cancer: a pooled analysis in the INHANCE consortium

We investigated the association between diet and head and neck cancer (HNC) risk using data from the International Head and Neck Cancer Epidemiology (INHANCE) consortium. The INHANCE pooled data included 22 case-control studies with 14,520 cases and 22,737 controls. Center-specific quartiles among the controls were used for food groups, and frequencies per week were used for single food items. A dietary pattern score combining high fruit and vegetable intake and low red meat intake was created. Odds ratios (OR) and 95% confidence intervals (CI) for the dietary items on the risk of HNC were estimated with a two-stage random-effects logistic regression model. An inverse association was observed for higher-frequency intake of fruit (4th vs. 1st quartile OR = 0.52, 95% CI = 0.43-0.62, p (trend) < 0.01) and vegetables (OR = 0.66, 95% CI = 0.49-0.90, p (trend) = 0.01). Intake of red meat (OR = 1.40, 95% CI = 1.13-1.74, p (trend) = 0.13) and processed meat (OR = 1.37, 95% CI = 1.14-1.65, p (trend) < 0.01) was positively associated with HNC risk. Higher dietary pattern scores, reflecting high fruit/vegetable and low red meat intake, were associated with reduced HNC risk (per score increment OR = 0.90, 95% CI = 0.84-0.97).

Proanthocyanidins and other flavonoids in relation to pancreatic cancer: a case-control study in Italy

BACKGROUND

Four cohort studies have examined the relation between flavonoids and pancreatic cancer risk providing inconsistent results.

PATIENTS AND METHODS

We conducted a case-control study between 1991 and 2008 in Northern Italy. Subjects were 326 cases with incident pancreatic cancer and 652 frequency-matched controls (admitted to the same hospitals as cases for acute non-neoplastic conditions) who answered a reproducible and valid food-frequency questionnaire. We computed odds ratios (ORs) using logistic regression models conditioned on gender, age and study center, and adjusted for education, history of diabetes, tobacco smoking, alcohol drinking and energy intake.

RESULTS

Proanthocyanidins with three or more mers were inversely related to pancreatic cancer risk. The ORs were similar in all classes of polymers with three or more mers and in their combination (OR for the highest versus the lowest quintile of intake, 0.41; 95% confidence interval 0.24-0.69), and did not substantially change after adjustment for fruit and vegetable consumption, and for vitamin C and folate intakes. Eating an additional portion of fruits rich in proanthocyanidins every day reduced the risk of pancreatic cancer by 25%.

CONCLUSION

Dietary proanthocyanidins-mostly present in apples, pears and pulses-may convey some protection against pancreatic cancer risk.

Risks and benefits of dietary isoflavones for cancer

A high intake of fruits and vegetables is associated with a lower risk of cancer. In this context, considerable attention is paid to Asian populations who consume high amounts of soy and soy-derived isoflavones, and have a lower risk for several cancer types such as breast and prostate cancers than populations in Western countries. Hence, interest focuses on soyfoods, soy products, and soy ingredients such as isoflavones with regard to their possible beneficial effects that were observed in numerous experiments and studies. The outcomes of the studies are not always conclusive, are often contradictory depending on the experimental conditions, and are, therefore, difficult to interpret. Isoflavone research revealed not only beneficial but also adverse effects, for instance, on the reproductive system. This is also the case with tumor-promoting effects on, for example, breast tissue. Isoflavone extracts and supplements are often used for the treatment of menopausal symptoms and for the prevention of age-associated conditions such as cardiovascular diseases and osteoporosis in postmenopausal women. In relation to this, questions about the effectiveness and safety of isoflavones have to be clarified. Moreover, there are concerns about the maternal consumption of isoflavones due to the development of leukemia in infants. In contrast, men may benefit from the intake of isoflavones with regard to reducing the risk of prostate cancer. Therefore, this review examines the risks but also the benefits of isoflavones with regard to various kinds of cancer, which can be derived from animal and human studies as well as from in vitro experiments.

Estimation of the intake of anthocyanidins and their food sources in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Anthocyanidins are bioactive flavonoids with potential health-promoting effects. These may vary among single anthocyanidins considering differences in their bioavailability and some of the mechanisms involved. The aim of the present study was to estimate the dietary intake of anthocyanidins, their food sources and the lifestyle factors (sex, age, BMI, smoking status, educational level and physisical activity) involved among twenty-seven centres in ten European countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Anthocyanidin intake and their food sources for 36 037 subjects, aged between 35 and 74 years, in twenty-seven redefined centres were obtained using standardised 24 h dietary recall software (EPIC-SOFT). An ad hoc food composition database on anthocyanidins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, petunidin) was compiled using data from the US Department of Agriculture and Phenol-Explorer databases and was expanded by adding recipes, estimated values and cooking factors. For men, the total anthocyanidin mean intake ranged from 19·83 (se 1·53) mg/d (Bilthoven, The Netherlands) to 64·88 (se 1·86) mg/d (Turin, Italy), whereas for women the range was 18·73 (se 2·80) mg/d (Granada, Spain) to 44·08 (se 2·45) mg/d (Turin, Italy). A clear south to north gradient intake was observed. Cyanidins and malvidins were the main anthocynidin contributors depending on the region and sex. Anthocyanidin intake was higher in non-obese older females, non-smokers, and increased with educational level and physical activity. The major food sources were fruits, wine, non-alcoholic beverages and some vegetables. The present study shows differences in both total and individual anthocyanidin intakes and various lifestyle factors throughout Europe, with some geographical variability in their food sources.

Selected aspects of Mediterranean diet and cancer risk

European Mediterranean populations have a high life expectancy. Several aspects of their diet are considered favorable on health. We considered the role of various aspects of the Mediterranean diet on cancer risk in a series of Italian case-control studies including about 10,000 cases of cancer at 13 different sites and over 17,000 controls. For most epithelial cancers, the risk decreased with increasing vegetable consumption. Allium vegetables were also favorably related to cancer risk. Fruit intake was inversely associated with digestive tract and laryngeal cancers. For digestive tract cancers, the population attributable risks for low intake of vegetables and fruit ranged between 15% and 40%. Olive oil and unsaturated fats, which are typical aspects of the Mediterranean diet, were inversely related to the risk of several cancers, particularly of the upper aerodigestive tract. Whole grain food (and hence possibly fiber) intake was also related to reduced risk of various cancers. In contrast, refined grains and, consequently, glycemic load and index were associated to increased risks. Several micronutrients and food components (including folate, flavonoids, and carotenoids) showed inverse relations with cancer risk, but the main component(s) responsible for the favorable effect of a diet rich in vegetables and fruit remain undefined.

Nutrient-based dietary patterns and laryngeal cancer: evidence from an exploratory factor analysis

BACKGROUND

The issue of diet and laryngeal cancer has been rarely addressed considering the potential role of dietary patterns.

METHODS

We examined this association using data from a case-control study carried out between 1992 and 2000. Cases were 460 histologically confirmed incident laryngeal cancers hospitalized in two Italian areas. Controls were 1,088 subjects hospitalized for acute nonneoplastic diseases unrelated to tobacco or alcohol consumption. Dietary habits were investigated through a 78-item food frequency questionnaire. A posteriori dietary patterns were identified through principal component factor analysis carried out on a selected set of 28 major nutrients. The internal reproducibility, robustness, and reliability of the identified patterns were evaluated. Odds ratios (OR) of laryngeal cancer and 95% confidence intervals (95% CI) were estimated using unconditional multiple logistic regression models on quartiles of factor scores.

RESULTS

We identified five major dietary patterns named "animal products," "starch-rich," "vitamins and fiber," "vegetable unsaturated fatty acids," and "animal unsaturated fatty acids." The vitamins and fiber dietary pattern was inversely associated with laryngeal cancer (OR, 0.35; 95% CI, 0.24-0.52 for the highest versus the lowest score quartile), whereas the animal products (OR, 2.34; 95% CI, 1.59-3.45) and the animal unsaturated fatty acids (OR, 2.07; 95% CI, 1.42-3.01) patterns were directly associated with it. There was no significant association between the vegetable unsaturated fatty acids and the starch-rich patterns and laryngeal cancer risk.

CONCLUSION

These findings suggest that diets rich in animal products and animal fats are directly related, and those rich in fruit and vegetables inversely related, to laryngeal cancer risk.

Proanthocyanidins and the risk of colorectal cancer in Italy

Proanthocyanidins are a group of polymers of flavanols. Animal and in vitro studies suggest they decrease cancer risk, particularly of colorectal cancer. We used data from an Italian case-control study to investigate whether proanthocyanidins are related to colorectal cancer risk. Cases were 1,953 patients with incident, histologically confirmed colorectal cancer (1,225 colon cancers, 728 rectal cancers). Controls were 4,154 patients admitted for acute, non-neoplastic conditions. A reproducible and valid food frequency questionnaire was used. We estimated odds ratios (ORs) through multiple logistic regression models, including terms for potential confounding factors, and energy intake. A trend of decreasing risk with increasing intake of proanthocyanidins emerged for all classes except monomers. The OR for the highest vs. the lowest quintile of intake was 0.82 for monomers and dimers combined, 0.88 for monomers, 0.75 for dimers, 0.74 for all polymers with three or more mers, 0.84 for trimers, 0.80 for 4-6 mers, 0.79 for 7-10 mers, 0.69 for more than 10 mers, and 0.74 for total proanthocyanidins. The associations were apparently stronger for rectal than for colon cancer, in the absence of significant heterogeneity. These results may explain the protective effect of vegetables and fruit on colorectal cancer.

Epidemiology, public health, and the rhetoric of false positives

BACKGROUND

As an observational science, epidemiology is regarded by some researchers as inherently flawed and open to false results. In a recent paper, Boffetta et al. [Boffetta P, McLaughlin JK, LaVecchia C, Tarone RE, Lipworth L, Blot WJ. False-positive results in cancer epidemiology: a plea for epistemological modesty. J Natl Cancer Inst 100:988-995 (2008)] argued that "epidemiology is particularly prone to the generation of false-positive results." They also said "the tendency to emphasize and over-interpret what appear to be new findings is commonplace, perhaps in part because of a belief that the findings provide information that may ultimately improve public health" and that "this tendency to hype new findings increases the likelihood of downplaying inconsistencies within the data or any lack of concordance with other sources of evidence." The authors supported these serious charges against epidemiology and epidemiologists with few examples. Although we acknowledge that false positives do occur, we view the position of Boffetta and colleagues on false positives as unbalanced and potentially harmful to public health.

OBJECTIVE

We aim to provide a more balanced evaluation of epidemiology and its contribution to public health discourse.

DISCUSSION

Boffetta and colleagues ignore the fact that false negatives may arise from the very processes that they tout as generating false-positive results. We further disagree with their proposition that false-positive results from a single study will lead to faulty decision making in matters of public health importance. In practice, such public health evaluations are based on all the data available from all relevant disciplines and never to our knowledge on a single study.

CONCLUSIONS

The lack of balance by Boffetta and colleagues in their evaluation of the impact of false-positive findings on epidemiology, the charge that "methodological vigilance is often absent" in epidemiologists' interpretation of their own results, and the false characterization of how epidemiologic findings are used in societal decision making all undermine a major source of information regarding disease risks. We reaffirm the importance of epidemiologic evidence as a critical component of the foundation of public health protection.

Dietary intake of selected flavonols, flavones, and flavonoid-rich foods and risk of cancer in middle-aged and older women

BACKGROUND

Flavonoids may protect against cancer development through several biological mechanisms. However, epidemiologic studies on dietary flavonoids and cancer risk have yielded inconsistent results.

OBJECTIVE

We prospectively investigated the association between the intake of selected flavonoids and flavonoid-rich foods and risk of cancers in the Women's Health Study.

DESIGN

A total of 3234 incident cancer cases were identified during 11.5 y of follow-up among 38,408 women aged > or = 45 y. Intake of individual flavonols (quercetin, kaempferol, and myricetin) and flavones (apigenin and luteolin) was assessed from food-frequency questionnaires. Cox regression models were used to estimate the relative risk (RR) of total and site-specific cancer across increasing intakes of total and individual selected flavonoids and flavonoid-rich foods (tea, apple, broccoli, onion, and tofu).

RESULTS

The multivariate RRs of total cancer across increasing quintiles of total quantified flavonoid intake were 1.00, 1.00, 0.93, 0.94, and 0.97 (P for trend = 0.72). For site-specific cancers, the multivariate RRs in the highest quintile of total quantified flavonoid intake compared with the lowest quintile were 1.03 for breast cancer, 1.01 for colorectal cancer, 1.03 for lung cancer, 1.15 for endometrial cancer, and 1.09 for ovarian cancer (all P > 0.05). The associations for the individual flavonoid intakes were similar to those for the total intake. There was also no significant association between intake of flavonoid-rich foods and the incidence of total and site-specific cancers.

CONCLUSION

Our results do not support a major role of 5 common flavonols and flavones or selected flavonoid-rich foods in cancer prevention.

Dietary flavonoid intake and risk of cancer in postmenopausal women: the Iowa Women's Health Study

Flavonoids, which are found in certain plant foods, are thought to lower cancer risk through their antioxidant, antiestrogenic and antiproliferative properties. We examined the association of intake of total flavonoids and 7 flavonoid subclasses with risk of lung, colorectal, breast, pancreatic and upper aerodigestive cancer among women in a large prospective cohort study. Study participants were 34,708 postmenopausal women in the Iowa Women's Health Study who completed a food frequency questionnaire and were followed for cancer occurrence from 1986 through 2004. Flavonoid intake was estimated from 3 databases developed by the USDA Nutrient Data Laboratory (NDL). Hazard ratios (HR) for cancer risk were calculated across total flavonoid and flavonoid subclass intake categories. Interactions between smoking history and flavonoid intake were also examined. After multivariable adjustment, lung cancer incidence was inversely associated with intakes of flavanones (HR = 0.68; 95% CI: 0.53-0.86, all results highest vs. lowest quintile) and proanthocyanidins (HR = 0.75; 95% CI: 0.57-0.97). Among current and past smokers, those with intakes in the highest quintile for flavanones (HR = 0.66; 95% CI: 0.50-0.86), and proanthocyanidins (HR = 0.66; 95% CI; 0.49-0.89) had significantly lower lung cancer incidence than those in the lowest quintile. Similar associations were not seen in never smokers. Isoflavone intake was inversely associated with overall cancer incidence (HR = 0.93, 95% CI: 0.86-1.00). This study provides further support for a beneficial effect of flavonoid intake on lung cancer risk, especially among current and past smokers.

Flavonoid intake and liver cancer: a case-control study in Greece

In the context of a case-control study undertaken in Greece, we examined the role of six flavonoid classes in the etiology of hepatocellular carcinoma (HCC), by viral status, and of cholangiocarcinoma (CAC). Data and blood samples were collected between 1995 and 1998. Information about dietary intakes and covariates, including chronic infection with hepatitis B (HBV) and C (HCV) virus, were available for 250 HBV and/or HCV positive HCC cases, 83 HBV and HCV negative HCC cases, six CAC cases, and 360 hospital controls. In logistic regression models including gender, age, education, tobacco smoking, and total energy intake, there were no distinct patterns with respect to either HCC virus positive and HCC virus negative in relation to total flavonoids or any class of flavonoids, with the exception of flavones. Flavone intake, mostly derived from spinach and peppers, was inversely associated with both virus positive (P-trend, 0.049) and virus negative (P-trend, 0.084) HCC. There was also a suggestion of an inverse association of CAC with flavan-3-ols, anthocyanidins, and total flavonoids which, however, has to be taken with due caution on account of the small number of cases of this rare tumor. We conclude that flavones may be inversely associated with HCC risk, irrespective of its dominant etiology (viral or non viral).

Flavonoids and the Risk of Oral and Pharyngeal Cancer: A Case-Control Study from Italy

The intake of flavonoids has been inversely related to the risk of various common neoplasms, but scanty data exist on oral and pharyngeal cancer. We used data from a case-control study conducted in Italy between 1992 and 2005 to examine the relationship between flavonoid intake and oral and pharyngeal cancer risk. The study included 805 cases with incident, histologically confirmed oral and pharyngeal cancer, and 2,081 hospital controls admitted for acute, nonneoplastic conditions. We have applied data on food and beverage content of six major classes of flavonoids, on dietary information collected through a validated food-frequency questionnaire. The odds ratios (OR) were calculated using multiple logistic regression models, conditioned on study center, sex, and age. After adjustment for education, tobacco, alcohol, body mass index, and non-alcohol energy intake, ORs for the highest versus the lowest quintile of intake were 0.51 [95% confidence intervals (95% CI), 0.37-0.71] for flavanones, 0.62 (CI, 0.43-0.89) for flavonols, and 0.56 (95% CI, 0.40-0.78) for total flavonoids. No significant association emerged for isoflavones (OR, 0.90), anthocyanidins (OR, 0.86), flavan-3-ols (OR, 0.84), and flavones (OR, 0.75). The ORs were consistent across strata of age, sex, education, body mass index, tobacco, and alcohol. After allowance for vegetable and fruit consumption, the inverse relations with total flavonoids and flavanones remained significant, whereas that with flavonols became nonsignificant. None of the associations were significant after further allowance for vitamin C, probably on account of the high collinearity between these compounds.