A cohort study of nutritional factors and endometrial cancer

Plasma Circulating Vitamin C Levels and Risk of Endometrial Cancer: A Bi-Directional Mendelian Randomization Analysis

Background

Observational studies indicated that circulating vitamin C (VitC) levels may be correlated with the risk of endometrial cancer (EC). However, the causal effects and direction between them were still unclear.

Methods

In this study, 11 single nucleotide polymorphisms (SNPs) robustly correlated with plasma VitC levels were extracted from the latest genome-wide association study (GWAS), containing 52,018 individuals. Genetic data of EC were obtained from the Endometrial Cancer Association Consortium (ECAC) (12,906 cases and 108,979 controls). An inverse-variance weighted method was utilized as the primary analysis of Mendelian randomization (MR), supplemented by the weighted median, MR Pleiotropy Residual Sum and Outlier test (MR-PRESSO), and MR-Egger methods. Additional sensitivity analyses excluding 3 SNPs with secondary phenotypes were conducted to rule out the possible pleiotropic effects. Potential impacts of several risk factors of EC, such as obesity, body mass index (BMI), hypertension, and diabetes on VitC levels, were assessed. We additionally evaluated the effects of VitC on LDL cholesterol levels, HDL cholesterol levels, and triglycerides levels to probe into the possible mediators in the VitC-EC pathway.

Results

Genetically predicted higher plasma VitC levels (per 1 SD increase, approximately 20 μmol/L) were causally associated with an increased risk of EC overall [odds ratio (OR) 1.374, 95% CI 1.128–1.674, p = 0.0016], supported by complementary sensitivity analyses. In the subgroup analyses, genetically predicted higher levels of VitC were associated with a tendency of increased risks of both endometrioid (OR_SD 1.324, 95% CI 0.959–1.829, p = 0.0881) and non-endometrioid histology (OR_SD 1.392, 95% CI 0.873–2.220, p = 0.1647) while without statistical significance. The association remained significant after the exclusion of the three pleiotropic SNPs (OR_SD 1.394, 95% CI 1.090–1.784, p = 0.0082). The confounders and mediators were unlikely to affect the VitC-EC relationship. The causal effect of EC on VitC levels was not supported (OR 1.001, 95% CI 0.998–1.004, p = 0.4468).

Conclusions

This bi-directional MR study demonstrated a causal risk role of higher circulating VitC at physiological levels on an increased risk of EC, which was independent of confounders and mediators. Further studies are warranted to elucidate the possible mechanisms.

Role of Vitamin C in Selected Malignant Neoplasms in Women

Since the first reports describing the anti-cancer properties of vitamin C published several decades ago, its actual effectiveness in fighting cancer has been under investigation and widely discussed. Some scientific reports indicate that vitamin C in high concentrations can contribute to effective and selective destruction of cancer cells. Furthermore, preclinical and clinical studies have shown that relatively high doses of vitamin C administered intravenously in ‘pharmacological concentrations’ may not only be well-tolerated, but significantly improve patients’ quality of life. This seems to be particularly important, especially for terminal cancer patients. However, the relatively high frequency of vitamin C use by cancer patients means that the potential clinical benefits may not be obvious. For this reason, in this review article, we focus on the articles published mainly in the last two decades, describing possible beneficial effects of vitamin C in preventing and treating selected malignant neoplasms in women, including breast, cervical, endometrial, and ovarian cancer. According to the reviewed studies, vitamin C use may contribute to an improvement of the overall quality of life of patients, among others, by reducing chemotherapy-related side effects. Nevertheless, new clinical trials are needed to collect stronger evidence of the role of this nutrient in supportive cancer treatment.

N-6 Polyunsaturated Fatty Acids and Risk of Cancer: Accumulating Evidence from Prospective Studies

Previous studies on the association between polyunsaturated fatty acids (PUFAs) and cancer have focused on n-3 PUFAs. To investigate the association between intake or blood levels of n-6 PUFAs and cancer, we searched the PubMed and Embase databases up to March 2020 and conducted a meta-analysis. A total of 70 articles were identified. High blood levels of n-6 PUFAs were associated with an 8% lower risk of all cancers (relative risk (RR) = 0.92; 95% confidence interval (CI): 0.86-0.98) compared to low blood levels of n-6 PUFAs. In the subgroup analyses by cancer site, type of n-6 PUFAs, and sex, the inverse associations were strong for breast cancer (RR = 0.87; 95% CI: 0.77-0.98), linoleic acid (LA) (RR = 0.91; 95% CI: 0.82-1.00), and women (RR = 0.88; 95% CI: 0.79-0.97). In the dose-response analysis, a 2% and 3% decrease in the risk of cancer was observed with a 5% increase in blood levels of n-6 PUFAs and LA, respectively. Thus, there was no significant association between n-6 PUFA intake and the risk of cancer. The pooled RR of cancer for the highest versus lowest category of n-6 PUFA intake was 1.02 (95% CI: 0.99-1.05). Evidence from prospective studies indicated that intake of n-6 PUFAs was not significantly associated with risk of cancer, but blood levels of n-6 PUFAs were inversely associated with risk of cancer.

Energy balance related lifestyle factors and risk of endometrial and colorectal cancer among individuals with lynch syndrome: a systematic review

Lifestyle factors related to energy balance, such as excess body weight, poor diet, and physical inactivity, are associated with risk of sporadic endometrial cancer (EC) and colorectal cancer (CRC). There are limited data on energy balance-related lifestyle factors and EC or CRC risk among individuals with lynch syndrome, who are at extraordinarily higher risk of developing EC or CRC. We conducted a systematic review of evidence related to weight status, weight change, dietary habits, and physical activity on EC and CRC risk among individuals with lynch syndrome. Findings are reported narratively. We searched Medline, EMBASE, CENTRAL, PubMed, and clinicaltrials.gov up to June 14th, 2018. In total, 1060 studies were identified and 16 were included. Three studies were related to EC and 13 to CRC. Overall, evidence suggests that weight status/weight change may not be associated with EC risk and multivitamin and folic-acid supplementation may be associated with decreased EC risk. Early-adulthood overweight/obese weight-status and adulthood weight-gain may be associated with increased CRC risk, whereas multivitamin supplementation, tea and high fruit intake, and physical activity may be associated with decreased CRC risk. Current evidence proposes that recommendations related to weight, some dietary habits, and physical activity recommended for the general public are also relevant to individuals with lynch syndrome. More research is needed, specifically prospective cohorts and randomized controlled trials, to determine if tailored recommendations are needed among individuals with lynch syndrome.

Dietary Fiber Intake and Endometrial Cancer Risk: A Systematic Review and Meta-Analysis

Epidemiological studies are inconclusive regarding the association between dietary fiber intake and endometrial cancer risk. Thus, we aimed to conduct a meta-analysis to clarify the association between dietary fiber and endometrial cancer risk. We searched the PubMed and ISI Web databases for relevant studies through March 2018. The association between dietary fiber and endometrial cancer risk was evaluated by conducting a meta-analysis including 3 cohort and 12 case⁻control studies. A significant negative association was observed between total dietary fiber intake and endometrial cancer risk in 11 case⁻control studies (odds ratios (OR) 0.76, 95% confidence interval (CI): 0.64⁻0.89, I² = 35.2%, p = 0.117), but a marginal positive association was observed in three cohort studies (relative risk (RR) 1.22, 95% CI: 1.00⁻1.49, I² = 0.0%, p = 0.995). Particularly, a negative association was observed in North America (OR = 0.70, 95% CI: 0.59⁻0.83, I² = 8.9%, p = 0.362). In addition, a positive association was observed in cereal fiber (RR = 1.26, 95% CI: 1.03⁻1.52, I² = 0.0%, p = 0.530, 3 cohort studies) and a negative association was observed in vegetable fiber (OR = 0.74, 95% CI: 0.58⁻0.94, I² = 0.0%, p = 0.445, 3 case⁻control studies). In conclusion, negative associations with endometrial cancer risk were observed for higher total dietary fiber intake and higher vegetable fiber intake in the case⁻control studies. However, results from the cohort studies suggested positive relationships of higher total fiber intake and higher cereal fiber intake with endometrial cancer risk.

Folate intake and the risk of endometrial cancer: A meta-analysis

Background

Folate may involve in various aspects of carcinogenesis. However, the relationship between folate intake and risk of many cancers, including endometrial cancer, is still inconclusive. We conducted a meta-analysis to systematically review the association.

Methods

Relevant studies were searched through three electronic databases (PubMed, Embase, and Web of Science) up to April 4, 2016. Population based prospective or case-control studies involving in investigating folate intake and risk of endometrial cancer were considered as eligible. Three investigators independently extracted data. Controversies were reconciled by discussing with a fourth investigator. Effect sizes of studies were pooled via a random effects model. Thereafter to explore the origin of heterogeneity among results of studies, a mixed effects model was employed with study design and dose of folate intake taken as covariates.

Results

Nine case-control studies and five cohort studies were included in the current meta-analysis. The result pooled from the highest category suggested a marginal negative association between folate intake and risk of endometrial cancer (OR=0.89 95% CI: 0.76-1.05). Based on the mixed effects model, in the highest category, the risk showed an increasing trend along with increment of folate intake (5% risk increase per 100μg/d, P=0.01).

Conclusion

A marginally negative association was observed between folate intake and endometrial cancer, which might subject to a threshold effect. More finely designed perspective studies or randomized trials are still needed to confirm the association.

Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health

Research into the analysis, physical properties and health effects of dietary fibre has continued steadily over the last 40–50 years. From the knowledge gained, countries have developed guidelines for their populations on the optimal amount of fibre to be consumed each day. Food composition tables from many countries now contain values for the dietary fibre content of foods, and, from these, combined with dietary surveys, population intakes have been determined. The present review assessed the uniformity of the analytical methods used, health claims permitted, recommendations and intakes, particularly from national surveys across Europe and around the world. It also assessed current knowledge on health effects of dietary fibre and related the impact of different fibre types on health. The overall intent was to be able to provide more detailed guidance on the types of fibre which should be consumed for good health, rather than simply a total intake figure, the current situation. Analysis of data indicated a fair degree of uniformity in the definition of dietary fibre, the method used for analysis, the recommended amount to be consumed and a growing literature on effects on digestive health and disease risk. However, national dietary survey data showed that intakes do not reach recommendations and very few countries provide guidance on the types of fibre that are preferable to achieve recommended intakes. Research gaps were identified and ideas suggested to provide information for more detailed advice to the public about specific food sources that should be consumed to achieve health benefits.

Dietary n-3 polyunsaturated fatty acids, fish consumption, and endometrial cancer risk: a meta-analysis of epidemiological studies

The relationship between intake of fish and n-3 fatty acids and endometrial cancer risk has not been consistent across epidemiological studies. We quantitatively assessed the aforementioned association through a systematic review and meta-analysis. PubMed and Embase were searched through March 2017 for eligible epidemiological studies. Fixed or random-effects models were used to pool relative risks (RRs) and 95% confidence intervals (CIs). The dose-response relationship was also evaluated. Based on the literature search, five prospective studies and 11 case-control studies were identified. All 16 studies were categorized as high-quality studies. After pooling available risk estimates, no significant association was detected between overall fish intake and endometrial cancer risk. In subgroup analyses, every one additional serving/week of fish intake was significantly associated with inversed endometrial cancer risk in studies adjusted for smoking (RR (95% CI): 0.95 (0.91-1.00)), or studies performed in Europe (RR (95% CI): 0.90 (0.84-0.97)), but not in other tested subgroups. In studies conducted in Asia, there was significant positive association (RR (95% CI): 1.15 (1.10-1.21)). Regarding n-3 PUFA intake, marginally inverse associations of high EPA or DHA intake were detected (EPA: RR (95% CI) = 0.79 (0.61-1.04); DHA: RR (95% CI) = 0.85 (0.64-1.11)). Dose-response analyses suggested a significant nonlinear relationship between DHA intake and endometrial cancer risk (p: 0.04). Overall, this meta-analysis suggests that intake of n-3 PUFA may be inversely associated with endometrial cancer risk at some level of evidence, although the exact relationship, especially for fish intake, needs further characterization. Further well-designed studies are warranted.

Does alcohol consumption modify the risk of endometrial cancer? A dose-response meta-analysis of prospective studies

BACKGROUND

Epidemiological studies have provided controversial evidence of an association between alcohol intake and endometrial cancer (EC) risk. The World Cancer Research Fund/American Institute for Cancer Research classifies alcohol as having a "limited-no conclusion" grade of evidence in the Endometrial Cancer 2013 Report (the latest version).

OBJECTIVE

The purpose of this meta-analysis is to systematically analyze the effect of alcohol intake on EC risk.

METHODS

We conducted a dose-response meta-analysis of prospective cohort studies identified from the PubMed, Embase, Cochrane Library and China Biological Medicine databases. Categorical and dose-response meta-analyses were conducted to estimate the effects of alcohol on EC risk.

RESULTS

A total of 10 studies involving 9766 cases and 1,612,798 participants were included in this meta-analysis. Overall, the relative risk(RR) for alcohol intake on EC was 1.04 (95% CI 0.88-1.22). The RRs for alcohol intake from wine, beer, and liquor were 1.10 (95% CI 0.80-1.51), 0.94 (95% CI 0.72-1.22), and 1.04 (95% CI 0.86-1.27), respectively). When alcohol consumption was stratified by drinking level, the RRs for moderate and heavy alcohol intake were 0.95 (95% CI 0.89-1.01) and 1.00 (95% CI 0.88-1.13), respectively. In the subgroup analyses, this association was not modified by other lifestyle factors or the characteristics of the study design and population. No significant associations were detected in the dose-response meta-analyses.

CONCLUSIONS

Alcohol intake is not associated with EC regardless of the beverage choice and alcohol consumption level. More studies are warranted in other populations, such as Asians and Africans.

Dietary fatty acids intake and endometrial cancer risk: a dose-response meta-analysis of epidemiological studies

Epidemiological studies have provided controversial evidence of the association between dietary fatty acids intake and endometrial cancer risk. The continuous update project of World Cancer Research Fund failed to focus on this issue. To address this inconsistency, we conducted this dose-response meta-analysis based on epidemiological studies published up to the end of June 2015 identified from PubMed, EMBASE and Web of Science. Two authors independently performed the eligibility evaluation and data extraction. Random-effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs). Fourteen epidemiological studies (4 cohort and 10 case-control studies) were included in this dose-response meta-analysis. The summary RR for an intake increment of 10g/day was 1.02 (95% CI = 0.97–1.08; I² = 66.0%) for saturated fatty acids, 0.98 (95% CI = 0.96–1.001; I² = 0%) for monounsaturated fatty acids, and 1.00 (95% CI = 0.95–1.06; I² = 0%) for polyunsaturated fatty acids intake. Non-significant results were observed in the majority of subgroup analyses stratified by study characteristics and adjustment for potential confounders in analyses of aforementioned associations. In conclusion, results from this dose-response meta-analysis provided limited evidence that dietary saturated, monounsaturated, and polyunsaturated fatty acids consumption was associated with endometrial cancer risk. Further studies, especial prospective designed or pooled studies are warranted to confirm our findings.

Dietary fat intake and endometrial cancer risk: A dose response meta-analysis

Since body fatness is a convincing risk factor for endometrial cancer, dietary fat intake was speculated to be associated with endometrial cancer risk. However, epidemiological studies are inconclusive. We aimed to conduct a meta-analysis to assess the associations between dietary fat intake and endometrial cancer risk. We searched the PubMed, Embase, and Web of science databases updated to September 2015. In total, 7 cohort and 14 case-control studies were included. Pooled analysis of case-control studies suggested that endometrial cancer risk was significantly increased by 5% per 10% kilocalories from total fat intake (P=0.02) and by 17% per 10 g/1000 kcal of saturated fat intake (P < 0.001). Summary of 3 cohort studies showed significant inverse association between monounsaturated fatty acids and endometrial cancer risk (odds ratio = 0.84, 95% confidence interval = 0.73-0.98) with a total of 524583 participants and 3503 incident cases. No significant associations were found for polyunsaturated fatty acids and linoleic acid. In conclusion, positive associations with endometrial cancer risk were observed for total fat and saturated fat intake in the case-control studies. Results from the cohort studies suggested higher monounsaturated fatty acids intake was significantly associated with lower endometrial cancer risk.

Dietary fat intake and endometrial cancer risk: dose-response meta-analysis of epidemiological studies

Epidemiological studies have provided controversial evidence of the association between dietary fat intake and endometrial cancer (EC) risk. To address this inconsistency, we conducted this dose-response meta-analysis by total dietary fat intake, based on epidemiological studies published up to the end of June 2015 identified from PubMed, EMBASE and Web of Science. Two authors (RH and Q-JW) independently performed the eligibility evaluation and data extraction. All differences were resolved by discussion with the third investigator (LJ). Random-effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs). Overall, the search yielded 16 studies (6 cohort and 10 case-control studies) that involved a total of 7556 EC cases and 563,781 non-cases. The summary RR for EC for each 30g/day increment intake was 0.98 (95%CI = 0.95–1.001; I² = 0%; n = 11) for total dietary fat. Non-significant results were observed in plant-based fat (summary RR = 1.05, 95%CI = 0.94–1.18; I² = 0%; n = 5) and animal-based fat (summary RR = 1.17, 95%CI = 0.92–1.36; I² = 85.0%; n = 6). Additionally, the null associations were observed in almost all the subgroup and sensitivity analyses. In conclusion, findings of the present meta-analysis suggested a lack of association between total dietary fat intake and EC risk. Further studies, especially prospective designed studies are warranted to confirm our findings.

Investigation of dietary factors and endometrial cancer risk using a nutrient-wide association study approach in the EPIC and Nurses' Health Study (NHS) and NHSII

Data on the role of dietary factors in endometrial cancer development are limited and inconsistent. We applied a "nutrient-wide association study" approach to systematically evaluate dietary risk associations for endometrial cancer while controlling for multiple hypothesis tests using the false discovery rate (FDR) and validating the results in an independent cohort. We evaluated endometrial cancer risk associations for dietary intake of 84 foods and nutrients based on dietary questionnaires in three prospective studies, the European Prospective Investigation into Cancer and Nutrition (EPIC; N = 1,303 cases) followed by validation of nine foods/nutrients (FDR ≤ 0.10) in the Nurses' Health Studies (NHS/NHSII; N = 1,531 cases). Cox regression models were used to estimate HRs and 95% confidence intervals (CI). In multivariate adjusted comparisons of the extreme categories of intake at baseline, coffee was inversely associated with endometrial cancer risk (EPIC, median intake 750 g/day vs. 8.6; HR, 0.81; 95% CI, 0.68-0.97, Ptrend = 0.09; NHS/NHSII, median intake 1067 g/day vs. none; HR, 0.82; 95% CI, 0.70-0.96, Ptrend = 0.04). Eight other dietary factors that were associated with endometrial cancer risk in the EPIC study (total fat, monounsaturated fat, carbohydrates, phosphorus, butter, yogurt, cheese, and potatoes) were not confirmed in the NHS/NHSII. Our findings suggest that coffee intake may be inversely associated with endometrial cancer risk. Further data are needed to confirm these findings and to examine the mechanisms linking coffee intake to endometrial cancer risk to develop improved prevention strategies.

Long-term alcohol intake and risk of endometrial cancer in the Nurses' Health Study, 1980-2010

BACKGROUND

Previous epidemiologic studies have shown inconsistent results for the association between alcohol intake and endometrial cancer risk. Most of the studies, however, assessed alcohol intake after cancer diagnosis, or measured alcohol intake at baseline only.

METHODS

We prospectively examined the association between alcohol intake and endometrial cancer risk in the Nurses' Health Study with 68 067 female participants aged 34-59 years in 1980. Alcohol intake was measured several times with validated dietary questionnaires. We calculated cumulative average alcohol intake to represent long-term intakes of individual subjects. Using Cox proportional hazards models, we estimated incidence rate ratios (RRs) and 95% confidence intervals (CIs) for endometrial cancer risk after controlling for several risk factors simultaneously.

RESULTS

We identified a total of 794 invasive endometrial adenocarcinoma from 1980 to 2010. We found an inverse association among alcohol drinkers (multivariable RR=0.81; 95% CI: 0.68-0.96) compared with nondrinkers. Women with light alcohol intake of <5 g per day (∼half drink per day) had a 22% lower risk of endometrial cancer (multivariable RR=0.78; 95% CI: 0.66-0.94). Higher intake of alcohol, however, did not provide additional benefits against endometrial cancer: multivariable RRs for 5-14.9 g (∼1 drink), 15-29.9 g (∼2 drinks), or ≥ 30 g (≥ 2 drinks) versus 0 g per day were 0.88, 0.83, and 0.78 (95% CI: 0.49-1.25), respectively. The lower risk among drinkers (∼half drink per day) appeared to be stronger for obese women, but no significant interaction by body mass index was found.

CONCLUSIONS

This study provides prospective evidence for an inverse association between light alcohol intake (∼half drink per day) in the long term and endometrial cancer risk, but above that level no significant association was found.

Overweight, obesity and endometrial cancer risk: results from a systematic review and meta-analysis

AIM

Findings from recent studies suggest that obesity may be associated with an increased risk of endometrial cancer, but several earlier studies were less conclusive. Here we strive to estimate this relationship in a meta-analysis of published data.

METHODS

We searched Pubmed and Embase for studies on body mass index and the risk of endometrial cancer, published from 1989 to 2011. Data were independently extracted and analyzed using random or fixed effects meta-analysis depending on the degree of heterogeneity.

RESULTS

Seven cohort studies and 11 case-control studies were included in the meta-analysis. Overall, the conditions of excess body weight ([EBW] defined as body mass index [BMI] ≥25 kg/m²), obesity (BMI ≥30 kg/m²) and overweight (25< BMI <30 kg/m²) were associated with an increased risk of endometrial cancer (relative risk [RR] for EBW=1.62, 95% confidence interval [CI], 1.39-1.89; for obesity RR=2.54, 95% CI, 2.11-3.06; for overweight RR=1.32, 95% CI, 1.16-1.50). Subgroup analyses showed that the positive associations were independent of study design, geographic locations, self-reported BMI, alcohol use, smoking habit, history of diabetes, hormone therapy, age at menarche, age at menopause, parity, and age at first full term pregnancy. However, there was no statistically significant association between EBW and endometrial cancer risk for measured BMI (for EBW RR=1.29, 95% CI, 0.66-2.53).

CONCLUSIONS

The findings from this meta-analysis strongly support that the conditions of EBW, overweight, and obesity are all associated with an increased risk of endometrial cancer. Also, the strength of the association increases with increasing BMI.

Dietary carbohydrate intake, glycemic index, and glycemic load and endometrial cancer risk: a prospective cohort study

Endometrial cancer risk has been directly associated with glycemic load. However, few studies have investigated this link, and the etiological role of specific dietary carbohydrate components remains unclear. Our aim was to investigate associations of carbohydrate intake, glycemic index, and glycemic load with endometrial cancer risk in the US Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Recruitment took place in 1993-2001. Over a median of 9.0 years of follow-up through 2009, 386 women developed endometrial cancer among 36,115 considered in the analysis. Dietary intakes were assessed using a 124-item diet history questionnaire. Cox proportional hazards models were applied to calculate hazard ratios and 95% confidence intervals. Significant inverse associations were detected between endometrial cancer risk and total available carbohydrate intake (hazard ratio (HR) = 0.66, 95% confidence interval (CI): 0.49, 0.90), total sugars intake (HR = 0.71, 95% CI: 0.52, 0.96), and glycemic load (HR = 0.63, 95% CI: 0.46, 0.84) when women in the highest quartile of intake were compared with those in the lowest. These inverse associations were strongest among overweight and obese women. No associations with endometrial cancer risk were observed for glycemic index or dietary fiber. Our findings contrast with previous evidence and suggest that high carbohydrate intakes and glycemic loads are protective against endometrial cancer development. Further clarification of these associations is warranted.

Whole grain, dietary fiber, and incidence of endometrial cancer in a Danish cohort study

Whole grains and dietary fiber might be inversely associated with endometrial cancer risk through their effects on sex hormone metabolism and body fat. We investigated whether a higher intake of whole grains and dietary fiber was associated with a lower incidence of endometrial cancer in the Diet, Cancer and Health cohort of 29,875 women aged 50-64 years at enrollment in 1993-1997. Information on diet and lifestyle was derived from self-administered questionnaires. The incidence rate ratios and 95% confidence intervals were estimated based on a Cox proportional hazards model. Of the 24,418 women included as cohort members, 217 had a diagnosis of endometrial cancer. No clear associations were found between intake of whole grains or dietary fiber and the incidence of endometrial cancer.

One-carbon metabolism factors and endometrial cancer risk

Background:

This is the largest prospective cohort analysis to assess how dietary factors involved in one-carbon metabolism are associated with endometrial cancer incidence, using 26 years of follow-up data from the Nurses’ Health Study.

Methods:

The prospective cohort analysis of one-carbon metabolism dietary factors used the Cox proportional hazards model, and incorporated 788 incident endometrial cancer events from 1980 to 2006. Genotyping and unconditional logistic regression were performed on 572 endometrial cancer cases and their matched controls to examine 29 mostly non-synonymous single-nucleotide polymorphisms involved in one-carbon metabolism.

Results:

There were no significant dose–response relationships between intake of any of the one-carbon metabolism dietary factors and endometrial cancer incidence, but alcohol consumption of <1 drink a day was significantly protective (hazard ratio: 0.80; 95% CI: 0.68, 0.94). Those with the MTHFR 677 TT or MTHFR 1298 CC genotype had more protective associations for many of the dietary factors and endometrial cancer, but statistical power was limited in this analysis.

Conclusion:

Dietary levels of folate, choline, methionine, vitamin B2, vitamin B6 or vitamin B12 do not appear to influence endometrial cancer incidence. Moderate alcohol intake may protect against developing endometrial cancer.

Omega-3 and omega-6 fatty acid intakes and endometrial cancer risk in a population-based case-control study

PURPOSE

Animal and laboratory studies suggest that long-chain omega-3 (n-3) fatty acids, a type of polyunsaturated fat found in fatty fish, may protect against carcinogenesis, but human studies on dietary intake of polyunsaturated fats and fish with endometrial cancer risk show mixed results.

METHODS

We evaluated the associations between endometrial cancer risk and intake of fatty acids and fish in a population-based sample of 556 incident cancer cases and 533 age-matched controls using multivariate unconditional logistic regression methods.

RESULTS

Although total n-3 fatty acid intake was not associated with endometrial cancer risk, higher intakes of eicosapentaenoic (EPA 20:5) and docosahexaenoic (DHA 22:6) fatty acids were significantly associated with lower risks (OR = 0.57, 95 % CI: 0.39-0.84; OR = 0.64, 95 % CI: 0.44-0.94; respectively) comparing extreme quartiles. The ratio of n-3:n-6 fatty acids was inversely associated with risk only on a continuous scale (OR = 0.84, 95 % CI: 0.71-0.99), while total fish intake was not associated with risk. Fish oil supplement use was significantly associated with reduced risk of endometrial cancer: OR = 0.63 (95 % CI: 0.45-0.88).

CONCLUSIONS

Our results suggest that dietary intake of the long-chain polyunsaturated fatty acids EPA and DHA in foods and supplements may have protective associations against the development of endometrial cancer.

Dietary folates and cancer risk in a network of case-control studies

BACKGROUND

Folate deficiency leads to DNA damage and inadequate repair, caused by a decreased synthesis of thymidylate and purines. We analyzed the relationship between dietary folate intake and the risk of several cancers.

PATIENTS AND METHODS

The study is based on a network of case-control studies conducted in Italy and Switzerland in 1991-2009. The odds ratios (ORs) for dietary folate intake were estimated by multiple logistic regression models, adjusted for major identified confounding factors.

RESULTS

For a few cancer sites, we found a significant inverse relation, with ORs for an increment of 100 μg/day of dietary folate of 0.65 for oropharyngeal (1467 cases), 0.58 for esophageal (505 cases), 0.83 for colorectal (2390 cases), 0.72 for pancreatic (326 cases), 0.67 for laryngeal (851 cases) and 0.87 for breast (3034 cases) cancers. The risk estimates were below unity, although not significantly, for cancers of the endometrium (OR = 0.87, 454 cases), ovary (OR = 0.86, 1031 cases), prostate (OR = 0.91, 1468 cases) and kidney (OR = 0.88, 767 cases), and was 1.00 for stomach cancer (230 cases). No material heterogeneity was found in strata of sex, age, smoking and alcohol drinking.

CONCLUSIONS

Our data support a real inverse association of dietary folate intake with the risk of several common cancers.

Total and individual antioxidant intake and endometrial cancer risk: results from a population-based case-control study in New Jersey

We evaluated the role of total dietary antioxidant capacity and of individual antioxidants on endometrial cancer risk in a population-based case-control study in New Jersey, including 417 cases and 395 controls. Dietary intake was ascertained using a food-frequency questionnaire (FFQ), and total antioxidant capacity (TAC) intake was estimated using the USDA Oxygen Radical Absorbance Capacity (ORAC) database and the University of Oslo's Antioxidant Food Database (AFD) and FFQ-derived estimates of intake. Odds ratios and 95 % confidence intervals were derived using multivariate logistic regression controlling for major endometrial cancer risk factors. Using the ORAC database, after adjusting for major covariates, we found decreased risks for the highest tertile of total phenolic intake compared with the lowest (OR: 0.62; 95 % CI: 0.39-0.98). There was no association for TAC intake based on the AFD, which utilized the ferric-reducing ability of plasma (FRAP) assay to assess antioxidant capacity. There was no strong evidence for an association with intake of any of the individual antioxidants. Our findings suggest that total phenolic consumption may decrease endometrial cancer risk.

American Cancer Society Guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity

The American Cancer Society (ACS) publishes Nutrition and Physical Activity Guidelines to serve as a foundation for its communication, policy, and community strategies and, ultimately, to affect dietary and physical activity patterns among Americans. These Guidelines, published approximately every 5 years, are developed by a national panel of experts in cancer research, prevention, epidemiology, public health, and policy, and they reflect the most current scientific evidence related to dietary and activity patterns and cancer risk. The ACS Guidelines focus on recommendations for individual choices regarding diet and physical activity patterns, but those choices occur within a community context that either facilitates or creates barriers to healthy behaviors. Therefore, this committee presents recommendations for community action to accompany the 4 recommendations for individual choices to reduce cancer risk. These recommendations for community action recognize that a supportive social and physical environment is indispensable if individuals at all levels of society are to have genuine opportunities to choose healthy behaviors. The ACS Guidelines are consistent with guidelines from the American Heart Association and the American Diabetes Association for the prevention of coronary heart disease and diabetes, as well as for general health promotion, as defined by the 2010 Dietary Guidelines for Americans and the 2008 Physical Activity Guidelines for Americans.

Risk of endometrial cancer in relation to individual nutrients from diet and supplements

OBJECTIVE

Intake of nutrients may influence the risk of endometrial cancer (EC). We aimed to estimate the association of intake of individual nutrients from food and from food plus supplements with EC occurrence.

DESIGN

A population-based case-control study conducted in Canada (2002-2006).

SETTING

Nutrient intakes from food and supplements were assessed using an FFQ. Logistic regression was used to estimate EC risk within quartile levels of nutrient intakes.

SUBJECTS

Incident EC cases (n 506) were identified from the Alberta Cancer Registry, and population controls were frequency- and age-matched to cases (n 981).

RESULTS

There existed little evidence of an association with EC for the majority of macronutrients and micronutrients examined. We observed a statistically significant increased risk associated with the highest, compared with the lowest, quartile of intake of dietary cholesterol (multivariable-adjusted OR = 1·51, 95 % CI 1·08, 2·11; P for trend = 0·02). Age-adjusted risk at the highest level of intake was significantly reduced for Ca from food sources (OR = 0·73, 95 % CI 0·54, 0·99) but was attenuated in the multivariable model (OR = 0·82, 95 % CI 0·59, 1·13). When intake from supplements was included in Ca intake, risk was significantly reduced by 28 % with higher Ca (multivariable-adjusted OR = 0·72, 95 % CI 0·51, 0·99, P for trend = 0·04). We also observed unexpected increased risks at limited levels of intakes of dietary soluble fibre, vitamin C, thiamin, vitamin B6 and lutein/zeaxanthin, with no evidence for linear trend.

CONCLUSIONS

The results of our study suggest a positive association between dietary cholesterol and EC risk and an inverse association with Ca intake from food sources and from food plus supplements.

Case-control study of dietary patterns and endometrial cancer risk

Dietary patterns, rather than intakes of specific foods or nutrients, may influence risk of endometrial cancer (EC). This population-based case-control study in Canada (2002-2006) included incident EC cases (n = 506) from the Alberta Cancer Registry and controls frequency age-matched to cases (n = 981). Past-year dietary patterns were defined using factor analysis of food frequency questionnaire data. Logistic regression was used to estimate EC risk within quartiles of dietary patterns. Three patterns (sweets, meat, plants) explained 23% of the variance in the dietary data. In multivariable models, EC risk was significantly reduced by 30% for women in the highest quartile of the healthier plants pattern (OR = 0.70, 95% CI 0.50-0.98, P trend = 0.02). When stratified by body mass index (BMI; kg/m(2)), risk was further reduced among overweight or obese women with a BMI ≥25 (OR = 0.57, 95% CI 0.39-0.83; P trend = 0.004). EC was not associated with the less healthy sweets and meat patterns. However, risk was modestly, but not significantly, elevated for higher intakes of the meat pattern among overweight or obese women. A mostly plant-based dietary pattern may reduce EC risk. Recommendations for risk reduction should focus on maintaining a healthy weight and the role of diet should be studied further.

The role of meat fat in the human diet

Food fat plays an important role in the human diet. On the one hand, fats provide the body with energy, contribute to the absorption of fat-soluble vitamins, and act as structural elements of cell walls. On the other hand, a high fat intake is associated with obesity, type 2 diabetes, cancer, and coronary heart disease. Animal fats, which contain a high proportion of saturated fatty acids, are often the focus of attention when it comes to reducing the share of fat in the diet. The present overview of the literature describes the amount of total fat and the percentage of individual fatty acid groups in meat and meat products, documents the contribution of meat and meat products to fat intake, and investigates the connection between meat fat and various diseases. The information given is based mainly on data material from Switzerland; data from other countries have been included for comparison.

Dietary fat, fiber, and carbohydrate intake in relation to risk of endometrial cancer

BACKGROUND

Macronutrients such as fat and fiber have been hypothesized to play a role in the etiology of endometrial cancer.

METHODS

To investigate these associations, the authors analyzed data from the Nurses' Health Study. From 1980 to 2006, 669 invasive adenocarcinoma cases were identified over 1.3 million person-years of follow-up. Dietary intake was assessed in 1980 and updated every 2-4 years. Cox proportional hazard models were used to calculate relative risks (RRs), controlling for total energy and other risk factors.

RESULTS

Overall, the authors found no significant associations between most dietary factors and endometrial cancer risk. Total fat was associated with a borderline significant decreased risk (top vs. bottom quintile RR = 0.78; 95% CI = 0.60-0.99; P(trend) = 0.18). Findings for animal fat were similar. No inverse associations between dietary fibers and cancer risk were observed. Cereal fiber was modestly positively associated with risk (top vs. bottom quintile RR = 1.38, 95% CI = 1.07-1.79; P(trend) = 0.05). The inverse association with animal fat intake and a positive association with carbohydrate intake were observed among premenopausal but not among postmenopausal women.

CONCLUSIONS

In this large prospective study, no overall association was observed between dietary fat, fiber, and carbohydrates with endometrial cancer risk, although several of the relationships may vary by menopausal status.

IMPACT

Dietary fat and fiber intake do not seem to play a major role in endometrial cancer etiology overall. However, further evaluation of these associations, particularly in premenopausal women, is needed.

Dietary and supplemental intake of one-carbon nutrients and the risk of type I and type II endometrial cancer: a prospective cohort study

BACKGROUND

Type I and II endometrial cancer are biologically and clinically distinct, with type II cancers having a high frequency of p53 mutations and an association with chromosomal instability. This raises the hypothesis that one-carbon nutrients (folate, methionine, and the enzymic cofactors vitamins B2, B6, and B12), which mediate chromosomal stability and DNA methylation, may be protective for type II but not type I endometrial cancer.

METHODS

Using a prospective cohort of 23 356 postmenopausal women followed 20 years, we estimated the relative risks (RRs) of type I (N = 471) and II (N = 71) endometrial cancers according to intake of one-carbon nutrients, adjusting for confounders.

RESULTS

No associations were observed between dietary or supplemental intake of any one-carbon nutrient and risk of type I cancer. For type II cancer, positive associations were due to supplemental, rather than dietary, intake of these nutrients: supplemental folate (RR = 1.80 for >228.6 versus 0 μg/day; P trend = 0.027) and vitamins B2 (RR = 1.94 for >1.70 versus 0 mg/day; P trend = 0.011), B6 (RR = 2.08 for >2.00 versus 0 mg/day; P trend = 0.012), and B12 (RR = 2.10 for >3.43 versus 0 μg/day; P trend = 0.0060).

CONCLUSION

Contrary to our hypothesis, use of supplements containing folate and vitamins B2, B6, and B12 was associated with an increased risk of type II endometrial cancer.

Antioxidant intake and risk of endometrial cancer: results from the Nurses' Health Study

To investigate the associations between antioxidant intake and risk of endometrial cancer, the authors analyzed data from the prospective Nurses' Health Study. From 1980 to 2006, 669 invasive adenocarcinoma cases were identified over 1.3 million person-years of follow-up. Information on dietary intake was collected in 1980 and updated every 2-4 years. Cox proportional hazard models were used to calculate the multivariate relative risks (RR), controlling for total energy and potential risk factors for endometrial cancer. Overall, the authors found no association between intakes of vitamins A, C, E or carotenoids from foods or supplements and cancer risk. The RR and 95% confidence intervals (CI) for the highest vs. lowest quintiles of vitamins A, C, E and total carotenoids were 1.09 (95% CI: 0.85-1.39), 0.98 (95% CI: 0.76-1.25), 1.07 (95% CI: 0.83-1.38) and 1.12 (95% CI: 0.86-1.45), respectively. Similarly, the use of multivitamins or specific vitamins A, C or E supplements was unassociated with risk. In subgroup analyses, several associations seemed to vary by postmenopausal hormone use. Our results suggest that there is no overall association between dietary antioxidant intake or use of antioxidant supplements with risk of endometrial cancer.

Alcohol intake and endometrial cancer risk: a meta-analysis of prospective studies

Background:

Studies on alcohol intake in relation to endometrial cancer risk have produced inconsistent results.

Methods:

For a meta-analysis, we identified cohort studies of alcohol and endometrial cancer by a literature search of Pub-Med and Embase up to 1 March 2010 and by searching the reference lists of relevant articles.

Results:

Seven cohort studies, including 1 511 661 participants and 6086 endometrial cancer cases, were included in the dose–response random-effect meta-regression model. Compared with non-drinkers, women drinking less than 1 drink of alcohol (13 g of ethanol) per day had a lower risk for endometrial cancer; this risk was lower by 4% (95% confidence interval (95% CI): 0.93–1.00) for consumption up to 0.5 drink per day and by 7% (95% CI: 0.85–1.02) for consumption up to 1 drink. However, we found evidence of an increased risk for endometrial cancer for intakes higher than two alcoholic drinks per day: compared with non-drinkers, the risk was higher by 14% (95% CI: 0.95–1.36) for 2–2.5 drinks per day and by 25% (95% CI: 0.98–1.58) for >2.5 drinks per day.

Conclusion:

Our meta-analysis indicates a possible J-shaped relationship between alcohol intake and endometrial cancer risk.

Fiber intake and endometrial cancer risk

BACKGROUND

The epidemiological evidence on the relation between dietary fiber intake and endometrial cancer is contradictory. Consequently, a case-control study was carried out to further investigate the role of dietary fiber intake in the etiology of endometrial cancer.

MATERIAL AND METHODS

Cases were 454 women with incident, histologically confirmed, endometrial cancer admitted to major teaching and general hospitals. Controls were 908 women admitted for acute, non-neoplastic conditions to the same hospital network. Information on diet was elicited using a validated food frequency questionnaire.

RESULTS

Odds ratios (OR) and 95% confidence intervals (CI) for quintiles of various types of fiber were estimated after allowance for total energy intake and other potential confounding factors. Lignin intake was significantly inversely related to endometrial cancer (OR=0.6 for the highest versus the lowest quintile of intake; 95%CI: 0.4-0.9) with a slightly significant linear trend in risk (p-value=0.04).

DISCUSSION

Data suggest the potential importance of lignin in the prevention of endometrial cancer at Italian consumption levels.

Alcohol and endometrial cancer risk: a case-control study and a meta-analysis

To evaluate the association between alcohol consumption and endometrial cancer risk, we analyzed data from a hospital-based case-control study, conducted in Italy between 1992 and 2006, on 454 endometrial cancer cases and 908 controls, and performed a meta-analysis updated to October 2009. Compared to never alcohol drinkers, the odds ratio was 1.03 (95% confidence interval, CI, 0.76-1.41) for < or = 7, 1.27 (95% CI 0.86-1.87) for 8-14, and 1.19 (95% CI 0.80-1.77) for > or = 15 drinks/week, with no trend in risk. No association emerged for wine, beer, and spirit consumption analyzed separately. The meta-analysis included 20 case-control and seven cohort studies, for a total of 13,120 cases. Compared to non/low drinkers, the pooled relative risks for drinkers were 0.90 (95% CI 0.80-1.01) for case-control studies, 1.01 (95% CI 0.90-1.14) for cohort studies, and 0.95 (95% CI 0.88-1.03) overall, with no heterogeneity between study design (p = 0.156). The overall estimate for heavy versus non/low drinkers was 1.12 (95% CI 0.87-1.45). The results were consistent according to selected study characteristics, including geographic area, definition of alcohol drinkers, and type of controls in case-control studies. Our findings provide evidence that alcohol drinking is not associated with endometrial cancer risk, although a weak positive association for very high drinkers cannot be excluded.

Dietary iron intake and risk of endometrial cancer: a population-based case-control study in Shanghai, China

Dietary red meat and animal fat have been linked to endometrial cancer (EC) risk, but the impact of bioavailable iron in animal-derived foods has been less well studied. Our objective was to investigate the effects of iron and fats on the risk of EC in a large, population-based, case-control study. The Shanghai Endometrial Cancer Study enrolled 1,204 EC cases and 1,212 controls who completed in-person interviews, including a food frequency questionnaire. Animal-derived iron and fat intakes were calculated from dietary intakes and food composition tables. Logistic regression models were used to evaluate independent and joint effects of iron and fat on EC risk. Animal-derived iron intake was positively associated with EC risk [adjusted OR = 1.9; 95% CI = 1.4-2.7, P(trend) < 0.01, highest vs. lowest quartile], predominantly after menopause (OR = 2.2; 95%CI = 1.4-3.4, P(trend) < 0.01) and in women with BMI >or= 25 kg/m(2)(OR = 3.2; 95% CI = 1.4-7.5 in postmenopausal obese women, P(trend) < 0.01). Animal-derived fat was also associated with postmenopausal EC risk (OR = 1.7; 95% CI = 1.2-2.5, P(trend) < 0.01). Multiplicative interactions between animal-derived iron and BMI or animal-derived fat intake were not observed. Animal-derived iron intake is associated with increased risk of EC after menopause and among obese women. Avoidance of animal-derived (heme) iron may reduce the risk of EC in these women.

Body size, adult BMI gain and endometrial cancer risk: the multiethnic cohort

The effect of body size and change in BMI on endometrial cancer risk across different racial/ethnic groups has not been studied. We examined the association between body size and endometrial cancer risk and potential effect modification of other risk factors among 50,376 women in the Multiethnic Cohort Study. During 10.3 years of follow-up, 463 endometrial cancer cases were identified. Epidemiologic data were collected from the baseline questionnaire. "BMI change" was defined as the percentage of body mass index change from age 21 to the time of recruitment. Women who were heavier at age 21 or at baseline (weight > or = 53.5 kg or > or = 63.9 kg, respectively) had an increased endometrial cancer risk compared to the lowest quartile of weight during the respective periods. BMI gain > or = 35% had a RR of 4.12 (95% CI: 2.69, 6.30) compared to the reference group (-5% < or = BMI change <+5%). Women who averaged an annual BMI gain > or = 1% had a >3.21-fold (95% CI: 2.37, 4.33) increased risk compared to women who maintained a stable adult BMI (-0.25 to <+0.25%). The highest risk associated with BMI gain was observed among nulliparous women and postmenopausal women who never used hormone therapy. Although African Americans and Whites showed an increase in risk after > or =35% BMI gain, Japanese Americans showed an increase in risk with much smaller gain (> or =5%). In conclusion, adult obesity and increase in adiposity are risk factors for endometrial cancer; and the risk associated with these factors may vary across racial/ethnic groups.

Long-term alcohol consumption and risk of endometrial cancer incidence: a prospective cohort study

Alcohol consumption has been hypothesized to increase the risk of endometrial cancer. We used data from the prospective population-based Swedish Mammography Cohort including 61,226 women to examine the association between alcohol and endometrial cancer incidence. Alcohol consumption was assessed with validated food frequency questionnaires at baseline 1987 to 1990 and at follow-up in 1997. During a mean follow-up of 17.6 years, 687 endometrial cancer cases were identified in the Swedish cancer registries. We found no association between alcohol consumption and endometrial cancer risk after adjustment for age, body mass index, and smoking. The multivariable rate ratios (95% confidence intervals) for the three upper categories of long-term alcohol consumption as compared with no consumption were 1.01 (0.84-1.22) for <3.4 g/d, 1.01 (0.80-1.27) for 3.4 to 9.9 g/d, and 1.09 (0.71-1.67) for >or=10 g/d, respectively. The association did not differ by age, body mass index, folic acid intake, or postmenopausal hormone use in stratified analysis. In conclusion, our results suggest that low alcohol consumption (up to one drink per day) is unlikely to substantially influence risk of endometrial cancer.

Higher regular coffee and tea consumption is associated with reduced endometrial cancer risk

Several studies have investigated the associations between diet and endometrial cancer, but few have focused specifically on coffee and tea. In a hospital-based case-control study, we examined the associations between endometrial cancer risk and usual consumption of coffee, decaffeinated coffee, and black tea among 541 women with endometrial cancer and 541 women with an intact uterus but without a cancer diagnosis seen at Roswell Park Cancer Institute (Buffalo, New York) between 1982 and 1998. Daily frequency of consumption of coffee, decaffeinated coffee, and black tea in the few years prior to diagnosis in cases and questionnaire completion in controls was assessed with a self-administered epidemiologic questionnaire and categorized as none, 0.5 cups/d, 1-2 cups/d and >2 cups/d. Odds ratios (OR) and 95% confidence intervals (CI) for each category referent to nondrinkers were estimated with unconditional logistic regression adjusting for age, endometrial cancer risk factors and each beverage mutually adjusted for other beverages. Compared to nondrinkers, we observed a nonsignificant negative association with endometrial cancer risk among women who reported >2 cups/d regular coffee (OR 0.71, 95% CI 0.49-1.03), a significant inverse association with >2 cups/d black tea (OR 0.56, 95% CI 0.35-0.90) and a significant inverse association with >4 cups/d combined coffee and tea consumption (OR 0.47, 95% CI 0.28-0.80). These findings suggest coffee and tea may be important in reducing endometrial cancer risk.

Higher intakes of vegetables and vegetable-related nutrients are associated with lower endometrial cancer risks

A limited number of studies have investigated diet in association with endometrial cancer (EC). We examined the association between intakes of selected food groups and nutrients with EC risk among 541 women with histologically confirmed EC and 541 women with an intact uterus and noncancer diagnoses seen at Roswell Park Cancer Institute between 1982 and 1998. Self-reported dietary and other epidemiologic data were collected by questionnaire. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% CI, adjusting for age, BMI, hormone replacement therapy use, cigarette smoking, lifetime duration of menstruation, and total energy intake. We observed significant inverse associations for women in the highest vs. lowest quartiles of intake of total vegetables (OR, 0.51; 95% CI, 0.34-0.75), vitamin E (OR, 0.44; 95% CI, 0.27-0.70), dietary fiber (OR, 0.60; 95% CI, 0.39-0.94), beta-carotene (OR, 0.55; 95% CI, 0.37-0.82), lutein (OR, 0.52; 95% CI, 0.34-0.78), and folate (OR, 0.57; 95% CI, 0.36-0.91). Our results support that vegetables and related nutrients are associated with decreased risk of EC.

Antioxidant vitamins and the risk of endometrial cancer: a dose-response meta-analysis

Antioxidant vitamins may reduce cancer risk by limiting oxidative DNA damage. To summarize and quantify the current epidemiologic evidence of an association between antioxidant vitamin intake and endometrial cancer, we conducted a systematic literature review and meta-analysis. One cohort and 12 case-control studies presenting relevant risk estimates were identified by conducting bibliographical searches through June 2008. Dose-response meta-analyses were conducted for beta-carotene, vitamin C, and vitamin E from food sources. Intake from supplements was not considered in the meta-analyses because of the few studies that reported relevant information. Based on case-control data, the random-effects summary odds ratios (OR) were, for beta-carotene: 0.88 (95% CI: 0.79-0.98) per 1,000 mcg/1,000 kcal (I2: 77.7%; p < 0.01); for vitamin C: 0.85 (95% CI: 0.73-0.98) per 50 mg/1,000 kcal (I2: 66.1%; p < 0.01); and, for vitamin E: 0.91 (95% CI: 0.84-0.99) per 5 mg/1,000 kcal (I2: 0.0%; p: 0.45). In contrast, the only prospective study identified provided little indication of an association. Although the current case-control data suggest an inverse relationship of endometrial cancer risk with dietary intakes of beta-carotene, vitamin C, and vitamin E from food sources, additional studies are needed, particularly cohort studies, to confirm an association.

Dietary glycaemic index, glycaemic load and endometrial and ovarian cancer risk: a systematic review and meta-analysis

Long-term consumption of a high glycaemic index (GI) or glycaemic load (GL) diet may lead to chronic hyperinsulinaemia, which is a potential risk factor for cancer. To date, many studies have examined the association between GI, GL and cancer risk, although results have been inconsistent, therefore our objective was to conduct a systematic review of the literature. Medline and Embase were systematically searched using terms for GI, GL and cancer to identify studies published before December 2007. Random effects meta-analyses were performed for endometrial cancer, combining maximally adjusted results that compared risk for those in the highest versus the lowest category of intake. Separate analysis examined risk by body mass index categories. Five studies examining GI and/or GL intake and endometrial cancer risk were identified. Pooled effect estimates for endometrial cancer showed an increased risk for high GL consumers (RR 1.20; 95% CI: 1.06–1.37), further elevated in obese women (RR 1.54; 95% CI: 1.18–2.03). No significant associations were observed for GI. Only two studies examined ovarian cancer and therefore no meta-analysis was performed, but results indicate positive associations for GL also. A high GL, but not a high GI, diet is positively associated with the risk of endometrial cancer, particularly among obese women.

Dietary intake of selected B vitamins in relation to risk of major cancers in women

Although folic acid has been investigated for its potential to inhibit carcinogenesis, few epidemiologic studies have assessed the effects of intake of thiamin, riboflavin, and niacin, which may reduce cancer risk by acting as cofactors in folate metabolism or by other mechanisms. Using data from a large cohort of Canadian women, we examined the association of dietary intake of these nutrients, as well as intake of folate, methionine, and alcohol, with cancers of the breast, endometrium, ovary, colorectum, and lung ascertained during an average of 16.4 years of follow-up. After exclusions, the following numbers of incident cases were available for analysis: breast, n=2491; endometrium, n=426; ovary, n=264; colorectum, n=617; and lung, n=358. Cox proportional hazard models were used to estimate risk of each cancer with individual nutrients and to explore possible effect modification by combinations of nutrients on cancer risk. Few significant associations of intake of individual B vitamins with the five cancers were observed. Alcohol consumption showed a modest positive association with breast cancer risk but not with risk of the other cancers. There was no evidence of effect modification among the nutrients. This large study provides little support for an association of dietary intake thiamin, riboflavin, niacin, folate, or methionine with five major cancers in women.

Carbohydrates and cancer: an overview of the epidemiological evidence

OBJECTIVE

To assess the epidemiological evidence on dietary carbohydrates and the risk of developing cancer.

METHOD

Review of published studies, concentrating on recent systematic reviews, meta-analyses and large prospective studies.

CONCLUSIONS

Carbohydrates have not been intensively investigated in epidemiological studies of diet and cancer. There is a moderately large amount of data on the possible association between dietary fibre and the risk for colorectal cancer; the results of studies have varied and no firm conclusion can be drawn, but the available data suggest that high intakes of dietary fibre possibly reduce the risk for colorectal cancer. There are also limited data which suggest that high intakes of sucrose might increase the risk for colorectal cancer and that high intakes of lactose might increase the risk for ovarian cancer. For other components of carbohydrates and other types of cancer, the available data are too sparse to draw even tentative conclusions. Further research is needed on the possible associations of carbohydrates with cancer risk.

Macronutrients, fatty acids and cholesterol intake and endometrial cancer

BACKGROUND

There is some evidence that dietary habits may influence the risk of endometrial cancer independently of body mass, although the role of diet on endometrial carcinogenesis is unclear.

PATIENTS AND METHODS

We carried out a multicenter case-control study from 1992 to 2006 in Italy on 454 women with incident, histologically confirmed endometrial cancer (age range 18-79 years) and 908 controls (age range 19-79 years) admitted to hospitals for acute, non-neoplastic diseases. A validated food-frequency questionnaire was used to estimate macronutrients, fatty acids and cholesterol intake. Logistic regression models, conditioned on age and study centre, and adjusted for major known risk factor of endometrial cancer and residual of energy intake were used to estimate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Significant direct associations were observed with intake of energy (OR = 1.7 for the highest versus the lowest quintile, 95% CI = 1.1-2.5), and cholesterol (OR = 2.1, 95% CI = 1.4-3.2), while a direct borderline association emerged with saturated fatty acids (OR = 1.3, 95% CI = 0.9-2.0). There was no association with proteins, sugars, starch, total fat and other selected fatty acids.

CONCLUSION

Energy and cholesterol intake were associated with endometrial cancer.

Association between dietary fiber and endometrial cancer: a dose-response meta-analysis

BACKGROUND

Endometrial cancer is the most common female gynecologic cancer in the United States. Excessive and prolonged exposure of the endometrium to estrogens unopposed by progesterone and a high body mass are well-established risk factors for endometrial cancer. Although dietary fiber has been shown to beneficially reduce estrogen concentrations and prevent obesity, its role in endometrial cancer has received relatively little attention.

OBJECTIVE

The objective was to summarize and quantify the current evidence of a role of dietary fiber consumption in endometrial cancer risk and to identify research gaps in this field.

DESIGN

We conducted a systematic literature review of articles published through February 2007 to summarize the current evidence of a relation between dietary fiber consumption and endometrial cancer risk and to quantify the magnitude of the association by conducting a dose-response meta-analysis.

RESULTS

Ten articles representing 1 case-cohort study and 9 case-control studies that evaluated several aspects of fiber consumption and endometrial cancer risk were identified through searches in various databases. On the basis of 7 case-control studies, the random-effects summary risk estimate was 0.82 (95% CI: 0.75, 0.90) per 5 g/1000 kcal dietary fiber, with no evidence of heterogeneity (I(2): 0%, P for heterogeneity: 0.55). The random-effects summary estimate was 0.71 (95% CI: 0.59, 0.85) for the comparison of the highest with the lowest dietary fiber intake in 8 case-control studies, with little evidence of heterogeneity (I(2): 20.8%, P for heterogeneity: 0.26). In contrast, the only prospective study that evaluated this association did not find an association.

CONCLUSIONS

Although the current evidence, based on data from case-control studies, supports an inverse association between dietary fiber and endometrial cancer, additional population-based studies, particularly cohort studies, are needed before definitive conclusions can be drawn.