Diet and risk of ovarian cancer in the California Teachers Study cohort

Association of pre- and post-diagnosis dietary total antioxidant capacity (TAC) and composite dietary antioxidant index (CDAI) with overall survival in patients with ovarian cancer: a prospective cohort study

BACKGROUND

The evidence on the relationship of dietary antioxidant nutrients with the survival of ovarian cancer (OC) remains scarce.

OBJECTIVE

This study aimed to investigate these associations in a prospective cohort of Chinese patients with OC.

METHODS

In this prospective cohort study, patients with epithelial OC completed a food frequency questionnaire at diagnosis and 12 months post-diagnosis, and were followed from 2015 to 2023. Dietary total antioxidant capacity (TAC) and composite dietary antioxidant index (CDAI) were calculated based on specific antioxidant nutrients. We examined the associations of pre-diagnosis, post-diagnosis, and changes from pre-diagnosis to post-diagnosis in TAC, CDAI, and representative antioxidant nutrients with overall survival (OS) among patients with OC. Multivariable Cox proportional-hazards models were applied to calculate the hazard ratios (HR) and 95% confidence intervals (CI). Dose-response relationships were evaluated by restricted cubic splines.

RESULTS

Among the total 560 patients with OC, there were 211 (37.68%) deaths during a median follow-up of 44.40 (interquartile range: 26.97-61.37) months. High pre-diagnosis TAC (HR = 0.58; 95% CI 0.38-0.8) and vitamin C intake (HRT3 vs. T1 = 0.36; 95% CI 0.21-0.61), and post-diagnosis TAC (HR = 0.57; 95% CI 0.37-0.8), CDAI (HR = 0.57; 95% CI 0.33-0.9), and β-carotene intake (HRT3 vs. T1 = 0.55; 95% CI 0.32-0.97) were significantly associated with improved OS. Compared to patients with constantly low pre- and post-diagnosis TAC and CDAI, those with consistently higher TAC (HRMedium-Medium vs. Low-Low = 0.53; 95% CI 0.29-0.97; HRHigh-High vs. Low-Low = 0.40; 95% CI 0.16-0.94) and CDAI (HRHigh-High vs. Low-Low = 0.33; 95% CI 0.12-0.88) experienced better OS.

CONCLUSION

High pre- and post-diagnosis TAC, and post-diagnosis CDAI were associated with improved OC survival, suggesting that consistent high-intake of antioxidant-rich food may be beneficial for the prognosis of OC.

Broccoli Consumption and Risk of Cancer: An Updated Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

The scientific literature has reported an inverse association between broccoli consumption and the risk of suffering from several types of cancer; however, the results were not entirely consistent across studies. A systematic review and meta-analysis of observational studies were conducted to determine the association between broccoli consumption and cancer risk with the aim of clarifying the beneficial biological effects of broccoli consumption on cancer.

METHODS

PubMed/MEDLINE, Web of Science, Scopus, Cochrane Library (CENTRAL), and Epistemonikos databases were searched to identify all published papers that evaluate the impact of broccoli consumption on the risk of cancer. Citation chasing of included studies was conducted as a complementary search strategy. The risk of bias in individual studies was assessed using the Newcastle-Ottawa Scale. A random-effects model meta-analysis was employed to quantitatively synthesize results, with the I2 index used to assess heterogeneity.

RESULTS

Twenty-three case-control studies (n = 12,929 cases and 18,363 controls; n = 31,292 individuals) and 12 cohort studies (n = 699,482 individuals) were included in the meta-analysis. The results suggest an inverse association between broccoli consumption and the risk of cancer both in case-control studies (OR: 0.64, 95% CI from 0.58 to 0.70, p < 0.001; Q = 35.97, p = 0.072, I2 = 30.49%-moderate heterogeneity; τ2 = 0.016) and cohort studies (RR: 0.89, 95% CI from 0.82 to 0.96, p = 0.003; Q = 13.51, p = 0.333, I2 = 11.21%-low heterogeneity; τ2 = 0.002). Subgroup analysis suggested a potential benefit of broccoli consumption in site-specific cancers only in case-control studies.

CONCLUSIONS

In summary, the findings indicate that individuals suffering from some type of cancer consumed less broccoli, suggesting a protective biological effect of broccoli on cancer. More studies, especially cohort studies, are necessary to clarify the possible beneficial effect of broccoli on several types of cancer.

Review of the Potential Role of Ascorbate in the Prevention and Treatment of Gynecological Cancers

Ascorbate (vitamin C) is an essential vitamin for the human body and participates in various physiological processes as an important coenzyme and antioxidant. Furthermore, the role of ascorbate in the prevention and treatment of cancer including gynecological cancer has gained much more interest recently. The bioavailability and certain biological functions of ascorbate are distinct in males versus females due to differences in lean body mass, sex hormones, and lifestyle factors. Despite epidemiological evidence that ascorbate-rich foods and ascorbate plasma concentrations are inversely related to cancer risk, ascorbate has not demonstrated a significant protective effect in patients with gynecological cancers. Adequate ascorbate intake may have the potential to reduce the risk of human papillomavirus (HPV) infection and high-risk HPV persistence status. High-dose ascorbate exerts antitumor activity and synergizes with chemotherapeutic agents in preclinical cancer models of gynecological cancer. In this review, we provide evidence for the biological activity of ascorbate in females and discuss the potential role of ascorbate in the prevention and treatment of ovarian, endometrial, and cervical cancers.

The Intake of Cruciferous Vegetables and the Risk of Ovarian Cancer: A Systematic Review and Dose-Response Meta-Analysis

INTRODUCTION

The link between cruciferous vegetables (CVs) and ovarian cancer (OC) is still uncertain. This meta-analysis is intended to investigate the association between CV consumption and the risk of OC, as well as to conduct a dose-response analysis to determine the degree of correlation between them.

METHODS

We systematically searched PubMed, Web of Science, Embase, and Cochrane Library databases between database creation and October 2023. The present meta-analysis has been duly registered and assigned the registration number CRD42023470299. This study followed the PRISMA guidelines. The statistical analysis was performed using Stata 14.0 software.

RESULTS

There were a total of 7 cohort studies and 7 case-control studies with 7,269 cases and 742,952 subjects. The combined relative risk (RR) of the highest intake of CVs was 0.90 (95% confidence intervals [CIs]: 0.84-0.96; I2 = 54.7%; p = 0.007) compared to the lowest intake of CVs. The odds ratio (OR) was 0.97 (95% CIs: 0.86-1.08; p = 0.192) for cohort studies, and the RR was 0.79 (95% CIs: 0.67-0.91; p = 0.167) for case-control studies. The intake of CVs and the risk of OC were linearly correlated. Adding 15 g of CVs to the diet each day decreased the likelihood of developing OC by almost 4% (RR = 0.963, 95% CIs: 0.905-1.025; p = 0.235).

CONCLUSIONS

Consumption of CVs may be linked to a lower risk of OC.

Addressing schoolteacher food and nutrition-related health and wellbeing: a scoping review of the food and nutrition constructs used across current research

BACKGROUND

Teachers form a large and essential workforce globally. Their wellbeing impacts personal health-related outcomes with flow on effects for the health, and wellbeing of their students. However, food and nutrition (FN) interventions that include teachers, typically neglect the impact of personal FN factors on a teachers' ability to achieve optimal nutrition-related health and wellbeing, and successfully fulfil their professional FN roles as health promoters, gate keepers, educators', and role models. The aim of this review was to scope FN constructs that have been studied internationally regarding teacher FN-related health and wellbeing.

METHODS

Six databases were searched, and papers extracted in June/July 2021. Eligibility criteria guided by the population, concept, context mnemonic included studies published after 2000, in English language, with an aspect of personal FN-related health and wellbeing, among in-service (practising) and pre-service (training), primary, and secondary teachers. Screening studies for inclusion was completed by two independent researchers with data extraction piloted with the same reviewers and completed by lead author, along with complete descriptive and thematic analysis.

RESULTS

Ten thousand six hundred seventy-seven unique articles were identified with 368 eligible for full text review and 105 included in final extraction and analysis. Sixty-nine descriptive studies were included, followed by 35 intervention studies, with the main data collection method used to assess both personal and professional FN constructs being questionnaires (n = 99 papers), with nutrition knowledge and dietary assessment among the most commonly assessed.

CONCLUSION

FN constructs are used within interventions and studies that include teachers, with diversity in constructs included and how these terms are defined. The evidence from this scoping review can be used to inform data collection and evaluation in future epidemiological and interventional research that addresses teacher FN-related health and wellbeing.

Vitamin D Intake, Blood 25-Hydroxyvitamin D, and Risk of Ovarian Cancer: A Meta-Analysis of Observational Studies

Background: In vitro research suggests that vitamin D may protect against the risk of ovarian cancer. However, ecological and epidemiologic evidence is still debatable. Materials and Methods: We searched eligible studies via MEDLINE and Web of Science databases, as well as a hand search to examine the association between vitamin D intake or blood 25(OH)D (25-hydroxyvitamin D) and ovarian cancer risk in a meta-analysis. The overall relative risk (RR) was determined using a random-effect model. Results: For ovarian cancer incidence, 15 observational studies were included [5,634 cases for vitamin D intake and 975 cases for blood 25(OH)D]. For overall vitamin D intake (from food and supplements), the pooled RR of ovarian cancer risk for the highest versus lowest groups was 0.92 (95% confidence interval [CI]: 0.74-1.14). For blood 25(OH)D levels, however, people with high blood 25(OH)D levels had 37% lower risk of ovarian cancer than those with low levels (pooled RR = 0.63; 95% CI: 0.42-0.93). By study design, the inverse association was stronger in case-control studies than in prospective studies. The dose-response meta-analysis also supports the inverse association between blood 25(OH)D levels and ovarian cancer risk. When the pooled RRs were restricted to studies that adjusted for body mass index (BMI), they tended to be stronger, but the difference by adjustment for BMI was not significant. Conclusion: Our findings suggest that having a high blood 25(OH)D level is associated with a lower risk of ovarian cancer. More well-designed prospective studies are needed to confirm the link between vitamin D status and ovarian cancer risk.

Dietary Vitamin A Intake and Circulating Vitamin A Concentrations and the Risk of Three Common Cancers in Women: A Meta-Analysis

BACKGROUND

According to relevant clinical research, dietary and circulating antioxidants vitamin A are connected with the risk of breast, cervical, and ovarian cancer in women. However, there was inconsistency between the findings. We completed this meta-analysis at the right moment to address this contradiction of the problem.

METHODS

Web of Science, Embase, and PubMed databases were searched using the proposed search strategy and filtered using the inclusion and exclusion criteria as well as the NOS quality score. As of May 2022, low intake or low concentration was used as a control, and odds ratio (OR) or relative risk (RR) and ninety-five percent confidence intervals (95% CI) were extracted for high intake. Stata 12.0 was used to process the data.

RESULTS

Our meta-analysis included a total of 49 studies, 29 on breast cancer, 10 on ovarian cancer, and 10 on cervical cancer. There were 38 case-control studies included, with 25,363 cases and 42,281 controls; there were 11 cohort studies included, 1,334,176 individuals were followed up, and finally 9496 obtained cancer. The pooled OR value results were as follows: diet or supplements (OR = 0.83, 95% CI 0.76-0.90, I ² = 56.1%) and serum or plasma (OR = 0.96, 95% CI 0.86-1.09, I ² = 29.5%). Subgroup analyses were performed according to cancer type, diet or supplements, serum or plasma, study type, and geographic regions.

CONCLUSIONS

In North American and Asian populations, high dietary consumption of vitamin A or supplements decreases the incidence of three cancers in women, with breast and ovarian cancers being more significant. However, high circulating vitamin A concentrations were not significantly connected with the risk of the three malignancies.

Consumption of flavonoids and risk of hormone-related cancers: a systematic review and meta-analysis of observational studies

BACKGROUND

Flavonoids seem to have hormone-like and anti-hormone properties so that the consumption of flavonoids may have potential effects on hormone-related cancers (HRCs), but the findings have been inconsistent so far. This meta-analysis was aimed to explore the association between flavonoids intake and HRCs risk among observational studies.

METHODS

Qualified articles, published on PubMed, EMBASE, and China National Knowledge Infrastructure (CNKI) from January 1999 to March 2022 and focused on relationships between flavonoids (total, subclass of and individual flavonoids) and HRCs (breast, ovarian, endometrial, thyroid, prostate and testicular cancer), were retrieved for pooled analysis. Random effects models were performed to calculate the pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Funnel plots and Begg's/Egger's test were used to evaluate the publication bias. Subgroup analyses and sensitivity analyses were conducted to explore the origins of heterogeneity.

RESULTS

All included studies were rated as medium or high quality. Higher consumption of flavonols (OR = 0.85, 95% CI: 0.76-0.94), flavones (OR = 0.85, 95% CI: 0.77-0.95) and isoflavones (OR = 0.87, 95% CI: 0.82-0.92) was associated with a decreased risk of women-specific cancers (breast, ovarian and endometrial cancer), while the higher intake of total flavonoids was linked to a significantly elevated risk of prostate cancer (OR = 1.11, 95% CI: 1.02-1.21). A little evidence implied that thyroid cancer risk was augmented with the higher intake of flavones (OR = 1.24, 95% CI: 1.03-1.50) and flavanones (OR = 1.31, 95% CI: 1.09-1.57).

CONCLUSIONS

The present study suggests evidence that intake of total flavonoids, flavonols, flavones, flavanones, flavan-3-ols and isoflavones would be associated with a lower or higher risk of HRCs, which perhaps provides guidance for diet guidelines to a certain extent.

TRIAL REGISTRATION

This protocol has been registered on PROSPERO with registration number CRD42020200720 .

Intake of Soy, Soy Isoflavones and Soy Protein and Risk of Cancer Incidence and Mortality

Background and Aims

Associations between soy intake and risk of cancer have been evaluated in prospective observational studies with inconsistent results. Whether the potential anticancer effects offered by soy were attributed to soy isoflavones and soy protein still needs to be elucidated. This study aimed to comprehensively quantify the association of soy, soy isoflavones and soy protein intake with risk of cancer incidence and cancer mortality by conducting a meta-analysis of all available studies.

Methods

PubMed, Embase, Web of Science, and Cochrane Library databases were searched up to 16 September 2021. Prospective cohort studies that examined the effect of soy, soy isoflavones and soy protein on cancer incidence and cancer mortality were identified. Random-effects models were used to pool the multivariable-adjusted relative risks (RRs) and corresponding 95% confidence intervals (CIs). The potential dose-response relations were explored by using generalized least-squares trend estimation.

Results

Eighty one prospective cohort studies were included in the meta-analysis. A higher intake of soy was significantly associated with a 10% reduced risk of cancer incidence (RR, 0.90; 95% CI, 0.83–0.96). Each additional 25 g/d soy intake decreased the risk of cancer incidence by 4%. Intake of soy isoflavones was inversely associated with risk of cancer incidence (RR, 0.94; 95% CI, 0.89–0.99), whereas no significant association was observed for soy protein. The risk of cancer incidence was reduced by 4% with each 10 mg/d increment of soy isoflavones intake. Similar inverse associations were also found for soy in relation to site-specific cancers, particularly lung cancer (RR, 0.67; 95%CI, 0.52–0.86) and prostate cancer (RR, 0.88; 95%CI, 0.78–0.99). However, high intake of soy, soy isoflavones and soy protein were not associated with cancer mortality.

Conclusions

Higher intake of soy and soy isoflavones were inversely associated with risk of cancer incidence, which suggested that the beneficial role of soy against cancer might be primarily attributed to soy isoflavones. These findings support recommendations to include soy as part of a healthy dietary pattern for the prevention of cancer.

Association about dietary vitamin C intake on the risk of ovarian cancer: a meta-analysis

Changes in dietary vitamin C intake have been related to the risks of various cancers. However, the association between dietary vitamin C intake and the risk of ovarian cancer has not been fully determined. A meta-analysis was performed to evaluate the relationship between vitamin C intake and ovarian cancer risk. Observational studies that evaluated the association between vitamin C intake and ovarian cancer risk were identified via systematic search of PubMed and Embase databases. A random-effect model was used to combine relative risk (RR) with corresponding 95% confidence intervals (CIs). As a result, 16 studies (5 cohort studies and 11 case–control studies) with 4553 cases and 439,741 participants were included. Pooled results showed that dietary vitamin C intake had non-significant association on the risk of ovarian cancer (RR = 0.95, 95%CI = 0.81–1.11, I² = 52.1%, P_{for heterogeneity} = 0.008). Subgroup analyses according to characteristics including geographic location and study design showed consistent results with the overall result. In summary, findings from the present study indicated that dietary vitamin C intake is not associated with the risk of ovarian cancer.

Dietary vitamin A intake and the risk of ovarian cancer: a meta-analysis

BACKGROUND: Previous studies have demonstrated some associations between dietary vitamin A intake and ovarian cancer risk with an inconsistent relationship. We therefore performed the present study to further explore the association between them.

METHODS: Databases of PubMed, Embase, and Web of Science were retrieved up to September 1, 2019. Summarized relative risk (RR) with corresponding 95% confidence intervals (CI) were calculated. Stata 14.0 software was used for data analysis.

RESULTS: Fifteen articles involving 4882 cases and 443,179 participants were included in this meta-analysis. A positive association between dietary vitamin A intake and ovarian cancer risk was found (RR = 0.816, 95%CI = 0.723–0.920, I² = 48.4%, P_{for heterogeneity} = 0.019). Significant association was also found in case–control studies (RR = 0.769, 95%CI = 0.655–0.902), but not in cohort studies. When we performed the analysis between ovarian cancer risk and geographic locations, we found an inverse association in North American populations (RR = 0.825, 95%CI = 0.720–0.946), instead of other populations.

CONCLUSIONS: In summary, findings from the present study suggested that higher dietary intake of vitamin A may contribute to the lower development of ovarian cancer, especially among North Americans.

Antioxidants and Therapeutic Targets in Ovarian Clear Cell Carcinoma

Ovarian clear cell carcinomas (OCCCs) are resistant to conventional anti-cancer drugs; moreover, the prognoses of advanced or recurrent patients are extremely poor. OCCCs often arise from endometriosis associated with strong oxidative stress. Of note, the stress involved in OCCCs can be divided into the following two categories: (a) carcinogenesis from endometriosis to OCCC and (b) factors related to treatment after carcinogenesis. Antioxidants can reduce the risk of OCCC formation by quenching reactive oxygen species (ROS); however, the oxidant stress-tolerant properties assist in the survival of OCCC cells when the malignant transformation has already occurred. Moreover, the acquisition of oxidative stress resistance is also involved in the cancer stemness of OCCC. This review summarizes the recent advances in the process and prevention of carcinogenesis, the characteristic nature of tumors, and the treatment of post-refractory OCCCs, which are highly linked to oxidative stress. Although therapeutic approaches should still be improved against OCCCs, multi-combinatorial treatments including nucleic acid-based drugs directed to the transcriptional profile of each OCCC are expected to improve the outcomes of patients.

The effect of folate intake on ovarian cancer risk: A meta-analysis of observational studies

BACKGROUND

Previous publications studied the correction about folate intake and ovarian cancer risk, with inconsistent results. This meta-analysis aimed to explore the association between folate intake and ovarian cancer risk using the existing published articles.

METHOD

We searched for relevant studies in electronic databases of PubMed, Web of Science, Embase, Cochrane, and Wanfang databases from inception to May 31, 2020. The overall relative risk (RR) and its 95% confidence intervals (95% CI) were pooled using a random-effect model.

RESULTS

A total of 12 articles with 6304 ovarian cancer cases were suitable for the inclusion criteria. The evaluated of the ovarian cancer risk with total folate intake and dietary folate intake were reported in 6 articles and 10 articles, respectively. Overall, highest category of dietary folate intake compared with lowest category had nonsignificant association on the risk of ovarian cancer (RR = 0.90, 95% CI = 0.77-1.06). The association was not significant between total folate intake and ovarian cancer risk (RR = 1.06, 95% CI = 0.89-1.27). The results in subgroup analyses by study design and geographic location were not changed either in dietary folate intake analysis or in total folate intake analysis.

CONCLUSION

Our meta-analysis demonstrates that folate intake had no significant association on the risk of ovarian cancer. Study design and geographic location were not associated with ovarian cancer while some other related factors were not investigated due to the limited information provided in each included study. Therefore, further studies are needed to verify our results.

Association of vitamin E on the risk of ovarian cancer: a meta-analysis

Many researches were conducted to assess the association of vitamin E intake on the risk of ovarian cancer, with conflict results. The current meta-analysis of published observational studies aimed to investigate the effect of vitamin E intake on ovarian cancer risk. The summary relative risks (RRs) with corresponding 95% confidence intervals (CIs) were calculated to measure the effectiveness of vitamin E intake on ovarian cancer risk using a random-effects model. As a result, 14 studies including 4597 patients were identified. Eleven studies reported about total vitamin E intake, eight studies about vitamin E intake from food only and five studies about vitamin E intake from supplement only on the risk of ovarian cancer. Overall, the summary RRs on ovarian cancer risk was 0.95 (95%CIs = 0.78–1.16) in total vitamin E intake, 0.99 (95%CIs = 0.77–1.27) in vitamin E intake from food only and 0.82 (95%CIs = 0.54–1.25) in vitamin E intake from supplement only. Results in subgroup analyses by study design and geographic location were consistent with overall result. In conclusions, the findings of this meta-analysis suggested that high intake of vitamin E from food or vitamin E supplement had no significant effect on the risk of ovarian cancer.

Potential effects of a high CO2 future on leguminous species

Legumes provide an important source of food and feed due to their high protein levels and many health benefits, and also impart environmental and agronomic advantages as a consequence of their ability to fix nitrogen through their symbiotic relationship with rhizobia. As a result of our growing population, the demand for products derived from legumes will likely expand considerably in coming years. Since there is little scope for increasing production area, improving the productivity of such crops in the face of climate change will be essential. While a growing number of studies have assessed the effects of climate change on legume yield, there is a paucity of information regarding the direct impact of elevated CO2 concentration (e[CO2]) itself, which is a main driver of climate change and has a substantial physiological effect on plants. In this review, we discuss current knowledge regarding the influence of e[CO2] on the photosynthetic process, as well as biomass production, seed yield, quality, and stress tolerance in legumes, and examine how these responses differ from those observed in non-nodulating plants. Although these relationships are proving to be extremely complex, mounting evidence suggests that under limiting conditions, overall declines in many of these parameters could ensue. While further research will be required to unravel precise mechanisms underlying e[CO2] responses of legumes, it is clear that integrating such knowledge into legume breeding programs will be indispensable for achieving yield gains by harnessing the potential positive effects, and minimizing the detrimental impacts, of CO2 in the future.

Association between vitamin D/calcium intake and 25-hydroxyvitamin D and risk of ovarian cancer: a dose-response relationship meta-analysis

BACKGROUND

The association between vitamin D/calcium and risk of ovarian cancer is still a debatable point. The aim of our study was to systematically investigate the association between vitamin D/calcium, and the risk of ovarian cancer and estimate their dose-response association quantitatively.

METHODS

PubMed, EMBASE, and Web of Science databases were searched to identify relevant observational studies. Two investigators screened citations and extracted data independently. Data were extracted and the association between vitamin D/calcium and ovarian cancer risk was estimated by calculating pooled relative risks (RRs). Subgroup analyses, publication bias estimation, and dose-response analyses were carried out as well.

RESULTS

In total, 21 articles involving 980,008 participants were included in our present study. No significant association was observed between total vitamin D intake and ovarian cancer risk (RR: 1.02; 95% CI, 0.89-1.16, p = 0.81). Further subgroup analysis suggested that neither dietary vitamin D intake (RR: 0.80; 95% CI, 0.62-1.03, p = 0.09) nor supplementary vitamin D intake (RR: 0.98; 95% CI, 0.85-1.13, p = 0.80) was associated with the risk of ovarian cancer. As for calcium, total calcium intake was found to be statistically inversely associated with ovarian cancer risk in case-control studies (RR: 0.73; 95% CI, 0.63-0.86, p < 0.001) but not in cohort studies (RR: 1.05; 95% CI, 0.90-1.24, p = 0.52). Besides, supplementation with calcium plus vitamin D was not effective for the prevention of ovarian cancer (p = 0.98). Of note, dose-response analysis based on cohort studies suggested a potential inverse U-shape relationship between calcium intake (including total calcium and dietary calcium) and ovarian cancer risk, which indicated that low dose of calcium intake might reduce ovarian cancer risk while high dose of calcium intake might not.

CONCLUSIONS

Taken together, vitamin D could not decrease the risk of ovarian cancer. The role of calcium intake was not proven for reducing ovarian cancer risk. Besides, no evidence showed combinative use of calcium and vitamin D have additional benefits for ovarian cancer prevention.

Association between dietary intake and risk of ovarian cancer: a systematic review and meta-analysis

PURPOSE

It is unclear how dietary intake influences the ovarian cancer. The present paper sets out to systematically review and meta-analyze research on dietary intake to identify cases having high- or low-risk ovarian cancer.

METHODS

Scopus, PubMed, and Wiley Online Libraries were searched up to the date November 24, 2019. Two reviewers were requested to independently extract study characteristics and to assess the bias and applicability risks with reference to the study inclusion criteria. Meta-analyses were performed to specify the relationship between dietary intake and the risk of ovarian cancer identifying 97 cohort studies.

RESULTS

No significant association was found between dietary intake and risk of ovarian cancer. The results of subgroup analyses indicated that green leafy vegetables (RR = 0.91, 95%, 0.85-0.98), allium vegetables (RR = 0.79, 95% CI 0.64-0.96), fiber (RR = 0.89, 95% CI 0.81-0.98), flavonoids (RR = 0.83, 95% CI 0.78-0.89) and green tea (RR = 0.61, 95% CI 0.49-0.76) intake could significantly reduce ovarian cancer risk. Total fat (RR = 1.10, 95% CI 1.02-1.18), saturated fat (RR = 1.11, 95% CI 1.01-1.22), saturated fatty acid (RR = 1.19, 95% CI 1.04-1.36), cholesterol (RR = 1.13, 95% CI 1.04-1.22) and retinol (RR = 1.14, 95% CI 1.00-1.30) intake could significantly increase ovarian cancer risk. In addition, acrylamide, nitrate, water disinfectants and polychlorinated biphenyls were significantly associated with an increased risk of ovarian cancer.

CONCLUSION

These results could support recommendations to green leafy vegetables, allium vegetables, fiber, flavonoids and green tea intake for ovarian cancer prevention.

Appraising the role of circulating concentrations of micro-nutrients in epithelial ovarian cancer risk: A Mendelian randomization analysis

To determine the causality of micro-nutrients concentrations and risk of ovarian cancer using the Mendelian randomization approach. Analyses were conducted using summary statistics data for SNPs robustly associated with concentrations of thirteen micro-nutrients (iron, copper, zinc, calcium, magnesium, phosphorus, selenium, vitamin A, β-carotene, vitamin B6, vitamin B12, vitamin E, folate). The corresponding data for ovarian cancer were obtained from the Ovarian Cancer Association Consortium (25,509 cases and 40,941 controls). In standard Mendelian randomization analysis, the odds ratios (OR) of invasive epithelial ovarian cancer were 0.14 (95% CI, 0.03-0.70; P = 0.02) per 0.1 mmol/L (about one standard deviation, SD) increase in genetically predicted magnesium concentration, 1.04 (95% CI, 1.00-1.09; P = 0.03) per 0.3 μmol/liter (about one SD) increase in genetically predicted β-carotene concentration. The OR of low malignant potential tumours were 0.82 (95% CI, 0.76-0.90; P = 1.01 × 10^-5) per 0.3 μmol/liter (about one SD) increase in β-carotene concentration, 1.42 (95% CI, 1.21-1.68; P = 3 × 10^-5) per 153 pmol/L (about one SD) increase in vitamin B12 concentration, 0.21 (95% CI, 0.06-0.76; P = 0.02) per 6 mg/L (about one SD) increase in vitamin E concentration. No significant associations of other micro-nutrients and ovarian cancer were observed. This study found that an increased risk of invasive epithelial ovarian cancer was observed with a genetically higher concentration of β-carotene, whereas a decreased risk of invasive epithelial ovarian cancer was found with a higher concentration of magnesium. As for low malignant potential tumours, increased concentration of vitamin B12 could increase the risk of low malignant potential tumours, while increased concentrations of β-carotene and vitamin E could lower the risk of low malignant potential tumours.

Effects of dairy products, calcium and vitamin D on ovarian cancer risk: a meta-analysis of twenty-nine epidemiological studies

Findings for the roles of dairy products, Ca and vitamin D on ovarian cancer risk remain controversial. We aimed to assess these associations by using an updated meta-analysis. Five electronic databases (e.g. PubMed and Embase) were searched from inception to 24 December 2019. Pooled relative risks (RR) with 95 % CI were calculated. A total of twenty-nine case–control or cohort studies were included. For comparisons of the highest v. lowest intakes, higher whole milk intake was associated with increased ovarian cancer risk (RR 1·35; 95 % CI 1·15, 1·59), whereas decreased risks were observed for higher intakes of low-fat milk (RR 0·84; 95 % CI 0·73, 0·96), dietary Ca (RR 0·71; 95 % CI 0·60, 0·84) and dietary vitamin D (RR 0·80; 95 % CI 0·67, 0·95). Additionally, for every 100 g/d increment, increased ovarian cancer risks were found for total dairy products (RR 1·03; 95 % CI 1·01, 1·04) and for whole milk (RR 1·07; 95 % CI 1·03, 1·11); however, decreased risks were found for 100 g/d increased intakes of low-fat milk (RR 0·95; 95 % CI 0·91, 0·99), cheese (RR 0·87; 95 % CI 0·76, 0·98), dietary Ca (RR 0·96; 95 % CI 0·95, 0·98), total Ca (RR 0·98; 95 % CI 0·97, 0·99), dietary vitamin D (RR 0·92; 95 % CI 0·87, 0·97) and increased levels of circulating vitamin D (RR 0·84; 95 % CI 0·72, 0·97). These results show that whole milk intake might contribute to a higher ovarian cancer risk, whereas low-fat milk, dietary Ca and dietary vitamin D might reduce the risk.

Caffeine, Type of Coffee, and Risk of Ovarian Cancer: A Dose-Response Meta-Analysis of Prospective Studies

CONTEXT

Prospective studies on caffeine and different types of coffee intake in relation to the risk of ovarian cancer have shown conflicting results.

OBJECTIVE

The aim of the present study was to perform a dose-response meta-analysis of cohort studies on the association between dietary caffeine intake, different types of coffee consumption, and the risk of ovarian cancer.

DATA SOURCES

PubMed/Medline, ISI Web of Science, Scopus, and EMBASE were searched to identify relevant studies reported until October 2018.

STUDY SELECTION

Prospective cohort studies that had considered caffeine or different types of coffee as the exposure variable and ovarian cancer as the main outcome variable or as one of the outcome variables were included in our systematic review and meta-analysis. Two of us independently screened 9344 publications. A total of 14 cohort studies were included in the meta-analysis.

DATA EXTRACTION

Two of us independently extracted the data. Any disagreements were resolved in consultation with the principal investigator.

RESULTS

Combining 13 effect sizes, we found no substantial association between coffee consumption and risk of ovarian cancer [risk ratio (RR), 1.08; 95% CI, 0.89 to 1.33]. Also, one additional cup daily of coffee consumption was marginally associated with an increased risk of ovarian cancer (RR, 1.02; 95% CI, 0.99 to 1.05; P = 0.21; I2 = 0.0%; Pheterogeneity = 0.68). No statistically significant association was observed between caffeine intake or caffeinated or decaffeinated coffee consumption and the risk of ovarian cancer.

CONCLUSIONS

We found no statistically significant association between caffeine intake or different types of coffee and the risk of ovarian cancer.

The Effects of the Dietary and Nutrient Intake on Gynecologic Cancers

The contribution of diet to cancer risk has been considered to be higher in advanced countries than in developing countries. In this paper, I review the current issues (a review of the relevant literature), and the effects of the dietary and nutrient intake on three types of gynecologic cancer (cervical, endometrial and ovarian cancers). In cervical cancer, the most important roles of diet/nutrition in relation to cancer are prophylaxis and countermeasures against human papillomavirus (HPV) infection. The main preventive and reductive factors of cervical cancer are antioxidants, such as vitamin A, C, D and E, carotenoids, vegetables and fruits. These antioxidants may have different abilities to intervene in the natural history of diseases associated with HPV infection. For endometrial cancer, the increase in peripheral estrogens as a result of the aromatization of androgens to estrogens in adipose tissue in obese women and insulin resistance are risk factors. Thus, we must mainly take care to avoid the continuous intake of fat energy and sugar. In ovarian cancer, the etiology has not been fully understood. To the best of our knowledge, the long-term consumption of pro-inflammatory foods, including saturated fat, carbohydrates and animal proteins is a risk factor. The intake of acrylamide is also a risk factor for both endometrial and ovarian cancer. Most papers have been epidemiological studies. Thus, further research using in vitro and in vivo approaches is needed to clarify the effects of the dietary and nutrient intake in detail.

Coffee and caffeine intake and risk of ovarian cancer: a systematic review and meta-analysis

BACKGROUND

Results from earlier publications on the association of coffee and caffeine and risk of ovarian cancer are inconsistent.

OBJECTIVE

To evaluate the link between coffee, caffeine, caffeinated coffee, and decaffeinated coffee consumption and risk of ovarian cancer.

METHODS

We searched PubMed/Medline, ISI Web of Science, Scopus, and Google Scholar to identify relevant publications up to April 2018. All case-control studies that considered coffee, caffeine, caffeinated coffee, or decaffeinated coffee as the exposure variables and ovarian cancer as the main outcome variable or as one of the outcomes were included in the systematic review. Publications in which odds ratios (ORs) or rate or risk ratios (RRs) and 95% confidence intervals (CIs) were reported, were included in the meta-analysis.

RESULTS

A total of 22 case-control studies were included in the systematic review, and 20 studies in the meta-analysis. Overall, 40 140 participants, including 8568 patients with ovarian cancer, aged ≥ 17 years were included. Combining 21 effect sizes from 18 studies, no significant association was observed between total coffee intake and risk of ovarian cancer (OR=1.09; 95% CI 0.94 to 1.26). There was no significant association between total caffeine intake and ovarian cancer risk (OR=0.89; 95% CI 0.55 to 1.45). In addition, caffeinated coffee intake was not significantly associated with ovarian cancer (OR=1.05; 95% CI 0.87 to 1.28). However, combining effect sizes from five studies, we found an inverse significant association between decaffeinated coffee intake and risk of ovarian cancer (OR=0.72; 95% CI 0.58 to 0.90).

CONCLUSIONS

Our findings indicated an inverse association between decaffeinated coffee consumption and risk of ovarian cancer. No significant association was found between coffee, caffeine or caffeinated coffee intake and risk of ovarian cancer.

Genistein Prevents Development of Spontaneous Ovarian Cancer and Inhibits Tumor Growth in Hen Model

Genistein, the major isoflavone in soybean, has been reported to exert anticancer effects on various types of cancer including ovarian cancer; however, its chemopreventive effects and mechanisms of action in ovarian cancer have not been fully elucidated in spontaneously developing ovarian cancer models. In this study, we demonstrated the preventive effects and mechanisms of genistein in the laying hen model that develops spontaneous ovarian cancer at high incidence rates. Laying hens were randomized to three groups: control (3.01 mg/hen, n = 100), low (52.48 mg/hen n = 100), and high genistein supplementation (106.26 mg/hen/day; per group). At the end of 78 weeks, hens were euthanized and ovarian tumors were collected and analyzed. We observed that genistein supplementation significantly reduced the ovarian tumor incidence (P = 0.002), as well as the number and size of the tumors (P = 0.0001). Molecular analysis of the ovarian tumors revealed that genistein downregulated serum malondialdehyde, a marker for oxidative stress and the expression of NFκB and Bcl-2, whereas it upregulated Nrf2, HO-1, and Bax expression at protein level in ovarian tissues. Moreover, genistein intake decreased the activity of mTOR pathway as evidenced by reduced phosphorylation of mTOR, p70S6K1, and 4E-BP1. Taken together, our findings strongly support the potential of genistein in the chemoprevention of ovarian cancer and highlight the effects of the genistein on the molecular pathways involved in ovarian tumorigenesis.

Impact of Elevated CO2 on Seed Quality of Soybean at the Fresh Edible and Mature Stages

Although the effect of elevated CO2 (eCO2) on soybean yield has been well documented, few studies have addressed seed quality, particularly at the fresh edible (R6) and mature stages (R8). Under the current global scenario of increasing CO2 levels, this potentially threatens the nutritional content and quality of food crops. Using four soybean cultivars, we assessed the effects of eCO2 on the concentrations of crude protein, crude oil, and isoflavones and analyzed the changes in free amino acids, fatty acids, and mineral elements in seeds. At R6, eCO2 had no influence on soybean seed protein and oil concentrations. At R8, eCO2 significantly decreased seed protein concentration but increased seed oil concentration; it also significantly decreased total free amino acid concentration. However, at the same stage, the proportion of oleic acid (18:1) among fatty acids increased in response to eCO2 in the cultivars of Zhongke-maodou 2 (ZK-2) and Zhongke-maodou 3 (ZK-3), and a similar trend was found for linoleic acid (18:2) in Zhongke-maodou 1 (ZK-1) and Hei-maodou (HD). Total isoflavone concentrations increased significantly at both the R6 and R8 stages in response to eCO2. Compared with ambient CO2, the concentrations of K, Ca, Mg, P, and S increased significantly under eCO2 at R6, while the Fe concentration decreased significantly. The response of Zn and Mn concentrations to eCO2 varied among cultivars. At R8 and under eCO2, Mg, S, and Ca concentrations increased significantly, while Zn and Fe concentrations decreased significantly. These findings suggest that eCO2 is likely to benefit from the accumulation of seed fat and isoflavone but not from that of protein. In this study, the response of seed mineral nutrients to eCO2 varied between cultivars.

The effect of the type of dietary protein on the development of ovarian cancer

We evaluated whether different dietary protein qualities (isocaloric diets involving animal (casein) or plant protein (soy protein) could inhibit the ovarian cancer growth in mice and improve their prognosis and whether chemotherapy had different tumor reducing effects on these mice. In the mice of the 20% plant protein group, the ovarian cancer growth at 5 weeks after tumor implantation was clearly reduced in comparison to the mice in the 20% animal protein group (p< 0.001). The serum levels of insulin and IGF-1 levels were both lower in the mice of the 20% plant protein group than in the mice of the 20% animal protein group (p<0.001 and p<0.01, respectively). Immunohistochemistry revealed that the level of eukaryotic initiation factor 4E-binding protein 1 (p-4EBP1) activity―one of the major downstream effectors of the mTOR pathway ―of the plant protein group was significantly weaker than that of the animal protein group (p<0.001). The prognosis of the 20% plant protein group was better than that of the 20% animal protein group (log-rank test, p=0.0062). The ovarian cancer growth in the 20% plant protein plus cisplatin treatment group was not significantly reduced in comparison to the 20% animal protein plus cisplatin treatment group. Our findings suggest that a diet high in plant protein reduces the growth of human ovarian cancer cells in mice compared to a diet high in animal protein, ―possibly through the lack of activation of the IGF/Akt/mTOR pathway, and leads to a better prognosis with or without cisplatin treatment.

Dietary fiber intake is associated with a reduced risk of ovarian cancer: a dose-response meta-analysis

Dietary fiber may reduce the bioavailability of steroid hormones and favorably regulate insulin-like growth factor 1, and therefore may be associated with ovarian cancer risk. Current evidence on the association between dietary fiber intake and risk of ovarian cancer is inconsistent. Therefore, we conducted a meta-analysis to explore the association. We hypothesized that dietary fiber intake might be associated with a reduced risk of ovarian cancer. PubMed, Web of Science, Embase, China National Knowledge Infrastructure, and Wanfang databases were searched for relevant articles up to September 2017. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using random-effects model. Dose-response relationship was assessed by restricted cubic spline. A total of 19 studies involving 567 742 participants were included in this meta-analysis. The summary RR of the association between dietary fiber intake and ovarian cancer risk was 0.70 (95% CI, 0.57-0.87; I² = 83.5%, P_{heterogeneity} < .001). In subgroup analyses, the above-mentioned significant inverse association was found among studies conducted in North America, case-control studies, and studies assessing the association of total fiber intake with ovarian cancer risk. Dose-response analysis suggested that ovarian cancer risk decreased by 3% (RR, 0.97; 95% CI, 0.95-0.99) for each 5-g/d increment in dietary fiber intake. This meta-analysis suggests that dietary fiber intake is associated with a reduced risk of ovarian cancer. Future intervention trials are needed to test the associations between different types of fiber (including soluble, insoluble, vegetable, fruit, cereal, and legumes fiber) and ovarian cancer risk.

Dietary fat intake and ovarian cancer risk: a meta-analysis of epidemiological studies

Observational studies assessing the association of dietary fat and risk of ovarian cancer yield discrepant results. Pertinent prospective cohort studies were identified by a PubMed search from inception to December 2015. Sixteen independent case-control and nine cohort studies on dietary fat intake were included, with approximately 900,000 subjects in total. Relative risks (RRs) with 95% confidence intervals were pooled using a random effects model. Heterogeneity, sensitivity analysis and publication bias were assessed; subgroup analysis and analysis stratified by EOC histology were conducted. The reported studies showed a significant increase of ovarian cancer risk with high consumption of total-, saturated-, and trans-fats, while serous ovarian cancer was more susceptible to dietary fat consumption than other pathological subtypes. No evidence of positive association between dietary fat intake and ovarian cancer risk was provided by cohort studies. Menopausal status, hormone replacement therapy, body mass index (BMI), and pregnancy times, modified the objective associations. In conclusion, the meta-analysis findings indicate that high consumption of total, saturated and trans-fats increase ovarian cancer risk, and different histological subtypes have different susceptibility to dietary fat.

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.

Calcium Intake and the Risk of Ovarian Cancer: A Meta-Analysis

Several epidemiological studies have evaluated the association between calcium intake and the risk of ovarian cancer. However, the results of these studies remain controversial. Thus, we performed a meta-analysis to explore the association between calcium intake and the risk of ovarian cancer. Pubmed, Embase and Web of Science were searched for eligible publications up to April 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Small-study effect was estimated using Egger's test and the funnel plot. Among 15 epidemiological studies involving 493,415 participants and 7453 cases eligible for this meta-analysis, 13 studies were about dietary calcium intake, 4 studies about dairy calcium intake and 7 studies about dietary plus supplemental calcium intake. When comparing the highest with the lowest intake, the pooled RRs of ovarian cancer were 0.80 (95% CI 0.72-0.89) for dietary calcium, 0.80 (95% CI 0.66-0.98) for dairy calcium and 0.90 (95% CI 0.65-1.24) for dietary plus supplemental calcium, respectively. Dietary calcium was significantly associated with a reduced risk of ovarian cancer among cohort studies (RR = 0.86, 95% CI 0.74-0.99) and among case-control studies (RR = 0.75, 95% CI 0.64-0.89). In subgroup analysis by ovarian cancer subtypes, we found a statistically significant association between the dietary calcium (RR = 0.78, 95% CI 0.69-0.88) and the risk of epithelial ovarian cancer (EOC). This meta-analysis indicated that increased calcium intake might be inversely associated with the risk of ovarian cancer; this still needs to be confirmed by larger prospective cohort studies.

Supplemental Selenium May Decrease Ovarian Cancer Risk in African-American Women

Background: To our knowledge, no previous study has evaluated the associations of antioxidant intake with the risk of ovarian cancer in African-American women, who are known to have high mortality from the disease.Objective: We sought to evaluate these associations among 406 ovarian cancer cases and 632 age- and site-matched controls of African-American descent recruited from AACES (African American Cancer Epidemiology Study), a population-based, case-control study in 11 geographical areas within the United States.Methods: Multivariable logistic regression models were used to estimate ORs and 95% CIs adjusted for a wide range of potentially confounding factors, including age, region, education, parity, oral contraceptive use, menopause, tubal ligation, family history, body mass index (BMI), smoking status, total energy, and physical activity.Results: Women with the highest intakes of supplemental selenium (>20 μg/d) had an ∼30% lower risk of ovarian cancer than those with no supplemental intake (OR: 0.67; 95% CI: 0.46, 0.97; P-trend = 0.035). This inverse association was stronger in current smokers (OR: 0.13; 95% CI: 0.04, 0.46; P-trend = 0.001). There was no association with dietary selenium. The associations with carotenoid intakes were weak and nonsignificant (P = 0.07-0.60). We observed no association with dietary or supplemental intake of vitamin C or vitamin E. There were no appreciable differences in results between serous and nonserous tumors.Conclusions: These findings provide the first insights, to our knowledge, into the potential association between antioxidants and ovarian cancer in African-American women, indicating potential inverse associations with supplemental selenium.

Ovarian cancer risk and nonisoflavone flavonoids intake: A systematic review of epidemiological studies

BACKGROUND

Although several studies have investigated the association between ovarian cancer risk and nonisoflavone flavonoids intake, these findings are inconsistent. This systematic review of published epidemiological studies was conducted to summarize and clarify the evidence on the association between ovarian cancer incidence and nonisoflavone flavonoids intake.

MATERIALS AND METHODS

PubMed, Scopus, Google Scholar, and EMBASE databases were searched based on MeSH term (ovarian neoplasm in combination with flavonoids) to identify related English and non-English papers published up to June 2016. We summarized the results of the relevant studies in this review.

RESULTS

In total, seven studies (four with cohort and three with case-control design) included in this review. The results of conducted cohort studies show no relation between ovarian cancer risk and total nonisoflavone flavonoids intake, and only one study reported a significant reduction between ovarian cancer incidence and kaempferol and luteolin intake. Similar to those in the cohort studies, also in case-control studies, no association was found between total nonisoflavone flavonoids intake and ovarian cancer risk, just an inverse association between flavonols intake and ovarian cancer was reported.

CONCLUSION

Several studies investigated the relation of nonisoflavone flavonoids intake and ovarian cancer risk; none of them reported any association for total nonisoflavone flavonoids intake, but some reported an inverse association between certain subclasses or individual flavonoids. These findings are limited, and there is a need for further and more accurate researches to be confirmed.

Dairy, calcium, vitamin D and ovarian cancer risk in African-American women

BACKGROUND

No previous study has evaluated the associations of dairy products, lactose, calcium and vitamin D with the risk of ovarian cancer in African-American women, who are known to have high mortality from the disease, as well as to be at risk for calcium and vitamin D deficiency.

METHODS

We evaluated these associations among 490 ovarian cancer cases and 656 age- and site-matched controls of African-American descent recruited into the African American Cancer Epidemiology Study, a population-based case-control study in 11 geographical areas in the US. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

An increased ovarian cancer risk was observed for whole milk consumption and lactose intake (highest quartile vs lowest: OR=1.97, 95% CI: 1.25-3.10;P-trend: 0.008). Calcium intake was associated with a decreased risk of ovarian cancer (OR=0.51, 95 CI%: 0.30-0.86; P-trend: 0.009), but vitamin D intake was not. Longer sun exposure in summer months was found to predict a lower risk (OR=0.71, 95% CI: 0.51-0.99; P-trend: 0.049).

CONCLUSIONS

Our findings suggest that a high-calcium, low-lactose diet, and sun exposure in summer months may reduce the risk of ovarian cancer in African-American women.

Dietary fat and fatty acid intake and epithelial ovarian cancer risk: evidence from epidemiological studies

The associations between dietary fat and fatty acid (FA) intakes and epithelial ovarian cancer (EOC) risk have been inconsistent in previous studies. We conducted a meta-analysis of epidemiological studies to evaluate these associations. We identified relevant studies by searching PubMed, EMBASE, and Web of Science databases. We used random-effects models to estimate summary relative risks (RRs) and 95% confidence intervals (CIs). Overall, the search yielded 20 studies (1 pooled analysis of 12 cohort studies, 5 cohorts, and 14 case-control studies). The summary RR for EOC for the highest versus lowest categories of total dietary fat intake was 1.12 (95%CI= 0.95–1.33; I² = 77.4%; n = 14). The RRs were not significant when fats were divided into plant-based fats (RR = 0.93, 95%CI = 0.77–1.13; n = 6), animal-based fats (RR = 1.15, 95%CI = 0.95–1.39; n = 8), dairy-based fats (RR = 1.02, 95%CI = 0.88–1.18; n = 3), saturated FAs (RR = 1.04, 95%CI = 0.93–1.17; n = 12), monounsaturated FAs (RR = 0.98, 95%CI = 0.84–1.13; n = 10), polyunsaturated FAs (RR = 0.96, 95%CI = 0.81–1.12; n = 10), and trans-unsaturated FAs (RR = 1.15, 95%CI = 0.98–1.36; n = 3). Similar non-significant results were also observed in most of the subgroup and sensitivity analyses. The findings of this meta-analysis suggest a lack of evidence for associations between dietary fat and FA intakes and EOC risk. Further analyses should be conducted to assess the associations with other types of fat, and the results should be stratified by tumor invasiveness and EOC histology.

Associations of Serum Isoflavone, Adiponectin and Insulin Levels with Risk for Epithelial Ovarian Cancer: Results of a Case-control Study

BACKGROUND

The aim of this study was to examine the association of serum isoflavones, adiponectin, and insulin levels with ovarian cancer risk.

MATERIALS AND METHODS

We gathered cases with histologically confirmed epithelial ovarian cancer at Sapporo Medical University Hospital from October 2010 to September 2012. Potential controls were recruited from female inpatients without any history of cancer or diabetes mellitus in different wards of the same hospital over the same period of time. Serum isoflavones, adiponectin, and insulin levels were measured in order to estimate associations with ovarian cancer risk in a case-control study. Data from 71 cases and 80 controls were analyzed with a logistic regression model adjusting for known risk factors.

RESULTS

A significant reduction in ovarian cancer risk was observed for the high tertile of serum daidzein level versus the low (Ptrend<0.001). A significant reduction in ovarian cancer risk was also observed for the high tertile of serum glycitein level versus the low (Ptrend=0.005). Furthermore, a significant reduction in ovarian cancer risk was observed for the high tertile of serum adiponectin level versus the low (Ptrend=0.004). Conversely, serum insulin level showed significantly elevated risk for ovarian cancer with the high tertile versus the low Ptrend<0.001).

CONCLUSIONS

Decreased serum isoflavones levels, such as those for daidzein and glycitein, decreased serum adiponectin levels, and increased serum insulin levels could be shown to be associated with elevated risk of ovarian cancer.

Association among Dietary Flavonoids, Flavonoid Subclasses and Ovarian Cancer Risk: A Meta-Analysis

Background

Previous studies have indicated that intake of dietary flavonoids or flavonoid subclasses is associated with the ovarian cancer risk, but presented controversial results. Therefore, we conducted a meta-analysis to derive a more precise estimation of these associations.

Methods

We performed a search in PubMed, Google Scholar and ISI Web of Science from their inception to April 25, 2015 to select studies on the association among dietary flavonoids, flavonoid subclasses and ovarian cancer risk. The information was extracted by two independent authors. We assessed the heterogeneity, sensitivity, publication bias and quality of the articles. A random-effects model was used to calculate the pooled risk estimates.

Results

Five cohort studies and seven case-control studies were included in the final meta-analysis. We observed that intake of dietary flavonoids can decrease ovarian cancer risk, which was demonstrated by pooled RR (RR = 0.82, 95% CI = 0.68–0.98). In a subgroup analysis by flavonoid subtypes, the ovarian cancer risk was also decreased for isoflavones (RR = 0.67, 95% CI = 0.50–0.92) and flavonols (RR = 0.68, 95% CI = 0.58–0.80). While there was no compelling evidence that consumption of flavones (RR = 0.86, 95% CI = 0.71–1.03) could decrease ovarian cancer risk, which revealed part sources of heterogeneity. The sensitivity analysis indicated stable results, and no publication bias was observed based on the results of Funnel plot analysis and Egger’s test (p = 0.26).

Conclusions

This meta-analysis suggested that consumption of dietary flavonoids and subtypes (isoflavones, flavonols) has a protective effect against ovarian cancer with a reduced risk of ovarian cancer except for flavones consumption. Nevertheless, further investigations on a larger population covering more flavonoid subclasses are warranted.

Evidence-Based Guideline of the German Nutrition Society: Fat Intake and Prevention of Selected Nutrition-Related Diseases

As nutrition-related chronic diseases have become more and more frequent, the importance of dietary prevention has also increased. Dietary fat plays a major role in human nutrition, and modification of fat and/or fatty acid intake could have a preventive potential. The aim of the guideline of the German Nutrition Society (DGE) was to systematically evaluate the evidence for the prevention of the widespread diseases obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease (CHD), stroke, and cancer through the intake of fat or fatty acids. The main results can be summarized as follows: it was concluded with convincing evidence that a reduced intake of total and saturated fat as well as a larger intake of polyunsaturated fatty acids (PUFA) at the expense of saturated fatty acids (SFA) reduces the concentration of total and low-density lipoprotein cholesterol in plasma. Furthermore, there is convincing evidence that a high intake of trans fatty acids increases risk of dyslipoproteinaemia and that a high intake of long-chain polyunsaturated n-3 fatty acids reduces the triglyceride concentration in plasma. A high fat intake increases the risk of obesity with probable evidence when total energy intake is not controlled for (ad libitum diet). When energy intake is controlled for, there is probable evidence for no association between fat intake and risk of obesity. A larger intake of PUFA at the expense of SFA reduces risk of CHD with probable evidence. Furthermore, there is probable evidence that a high intake of long-chain polyunsaturated n-3 fatty acids reduces risk of hypertension and CHD. With probable evidence, a high trans fatty acid intake increases risk of CHD. The practical consequences for current dietary recommendations are described at the end of this article.

Phytoestrogen intake and risk of ovarian cancer: a meta- analysis of 10 observational studies

BACKGROUND

Epidemiology studies have shown an inconclusive relationship between phytoestrogen intake and ovarian cancer risk and there have been no relevant meta-analyses directly regarding this topic. The purpose of the present meta-analysis was therefore to investigate any association between phytoestrogen intake and ovarian cancer in detail.

MATERIALS AND METHODS

We conducted a search of PubMed, EMBASE, EBSCO, the Cochrane Library, CNKI and Chinese Biomedical Database (up to April 2014) using common keywords for studies that focused on phytoestrogen and ovarian cancer risk. Study-specific risk estimates (RRs) were pooled using fixed effect or random-effect models.

RESULTS

Ten epidemiologic studies were finally included in the meta-analysis. The total results indicated higher phytoestrogen intake was associated with a reduced ovarian cancer risk (RR, 0.70; 95%CI: 0.56-0.87). The association was similar in sensitivity analysis. Meta regression analysis demonstrated sources and possibly types and regions as heterogeneous factors. Subgroup analysis of types, sources and regions showed that isoflavones (RR: 0.63; 95%CI: 0.46, 0.86), soy foods (RR: 0.51; 95%CI: 0.39, 0.68) and an Asian diet (RR: 0.48; 95%CI: 0.37, 0.63) intake could reduce the incidence of ovarian cancer.

CONCLUSIONS

Our findings show possible protection by phytoestrogens against ovarian cancer. We emphasize specific phytoestrogens from soy foods, but not all could reduce the risk. The habit of plentiful phytoestrogen intake by Asians is worthy to recommendation. However, we still need additional larger well designed observational studies to fully characterize underlying associations.

A prospective cohort study of dietary indices and incidence of epithelial ovarian cancer

BACKGROUND

Several dietary indices have been developed to measure overall diet quality, including the Healthy Eating Index-2005 (HEI-2005), which measures adherence to the 2005 Dietary Guidelines from the USDA; the Alternative Healthy Eating Index-2010 (AHEI-2010), which is based on foods and nutrients predictive of chronic disease risk; and the Alternate Mediterranean Diet Score (aMDS), which is an index that characterizes traditional food patterns of Mediterranean countries. Few studies have evaluated diet quality and ovarian cancer risk.

METHODS

We assessed the associations of the HEI-2005, AHEI-2010, and aMDS with risk of epithelial ovarian cancer prospectively among women in the Nurses' Health Study. We used Cox proportional hazards models, adjusting for known ovarian cancer risk factors.

RESULTS

During 24 years of follow-up, we documented 696 incident epithelial ovarian cancer cases among 82,948 women with diet information. The multivariate adjusted hazard ratios (95% confidence interval; Ptrend) of epithelial ovarian cancer comparing the highest with the lowest quintile were 1.03 (0.80-1.34; 0.77) for the AHEI-2010, 0.85 (0.65-1.12; 0.57) for the HEI-2005, and 0.91 (0.71-1.18; 0.44) for the aMDS.

CONCLUSIONS

We did not observe any clear association of three diet quality scores with ovarian cancer risk. Further work should other metrics of evaluating diet quality that may be more relevant cancer risk.

Erythrocyte saturated fatty acids and systemic inflammation in adults

OBJECTIVE

The role of saturated fatty acids (SFAs) in chronic disease remains controversial; inflammation is one pathway by which SFAs influence the risk for chronic disease. The aim of this study was to investigate the associations between red blood cell (RBC) phospholipid SFAs and systemic inflammation.

METHODS

As part of a randomized controlled trial, we measured RBC phospholipid FA composition in 55 generally healthy adults twice at 3-mo intervals. We estimated associations of RBC total SFAs and two major SFA subtypes, palmitic and stearic acids, with C-reactive protein (CRP), interleukin (IL)-6, white blood count (WBC), and a composite inflammation measure using generalized estimating equations in multivariable FA substitution models.

RESULTS

Mean (±SD) SFA level across both visits was 45% ± 3% of the total RBC FAs, mainly palmitic (21% ± 1%) and stearic (17% ± 3%) acids. In models adjusted for age, sex, race, smoking, body mass index, statin use, aspirin use, transunsaturated FAs, and ω-3 FAs, SFAs were significantly associated with IL-6 (20% increase per 1 SD increment; 95% confidence interval [CI], 0.03%-43%; P = 0.05) and the composite inflammation measure (P = 0.05) and marginally associated with CRP (34% increase; 95% CI, -1% to 81%; P = 0.06), but not associated with WBC. Stearic acid was positively associated with CRP (35% increase; 95% CI, 2%-79%; P = 0.04). Palmitic acid was marginally associated with the composite inflammation measure (P = 0.06) and, upon additional ω-6 FA adjustment, significantly associated with IL-6 (15% increase; 95% CI, 0.4%-27%; P = 0.006).

CONCLUSIONS

RBC SFAs, which represent longer-term dietary intake, are positively associated with inflammation. In particular, palmitic acid was associated with IL-6, and stearic acid was associated with CRP after multivariable adjustment.

Dietary fat intake and risk of epithelial ovarian cancer in the European Prospective Investigation into Cancer and Nutrition

There are inconsistent and limited data available to assess the relationship between fat intake and risk of epithelial ovarian cancer (EOC). We examined the consumption of total fat, fat sources and fat subtypes in relation to risk of EOC and its major histologic subtypes in the European Prospective Investigation into Cancer and Nutrition which includes incident invasive (n=1095) and borderline (n=96) EOC. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). In multivariate models, we observed no association with consumption of total fat, animal or plant fat, saturated fat, cholesterol, monounsaturated fat, or fatty fish and risk of invasive EOC. There was, however, an increased risk of invasive EOC in the highest category of intake (Quartile 4 vs. Quartile 1) of polyunsaturated fat (HR=1.22, 95% CI=1.02-1.48, P(trend)=0.02). We did not observe heterogeneity in the risk associations in comparisons of serous and endometrioid histologic subtypes. This study does not support an etiological role for total fat intake in relation to EOC risk; however, based on observations of a positive association between intake of polyunsaturated fat and invasive EOC risk in the current and previous studies, this fat subtype warrants further investigation to determine its potential role in EOC development.

Genistein as a Potential Anticancer Agent against Ovarian Cancer

Genistein is known as the major component of isoflavone, which is present in high-soy diets. Genistein has received much attention because of its chemopreventive and therapeutic effects on various types of cancers. Numerous studies have shown that genistein has antineoplastic effects against ovarian cancer. Several epidemiological studies have shown that women who have high consumption of isoflavones have a relatively low incidence of ovarian cancer. Genistein inhibits ovarian carcinogenesis by pleiotropic mechanisms. A higher affinity to estrogen receptor β is one probable explanation for its ability to reduce the risk of ovarian cancer. Genistein also targets multiple cellular signal transduction pathways associated with cell cycle regulation and apoptosis. In addition, genistein has been suggested to have antiangiogenic and antioxidant activities. Herein, we summarize recent results from epidemiological and experimental studies to identify the role of genistein in ovarian cancer. Further studies are needed to achieve conclusive results and determine the clinical applications of genistein.

Soy and isoflavone intake associated with reduced risk of ovarian cancer in southern Chinese women

Isoflavones, mainly found in soy, have been shown to inhibit ovarian cancer cell proliferation. We hypothesized that soy consumption and isoflavone intake are related to the risk of ovarian cancer. A case-control study was conducted in southern China to ascertain this hypothesis. Five hundred incident patients with histologically confirmed cancer of the ovary and 500 controls (mean age 59 years) were recruited from four public hospitals in Guangzhou. Information on habitual consumption of soy foods, including soybean, soy milk, fresh tofu, dried tofu, and soybean sprout, was obtained face-to-face from participants through a validated and reliable semi-quantitative food frequency questionnaire. Isoflavone intakes were then estimated using the USDA nutrient database. The ovarian cancer patients reported lower consumption levels of individual and total soy foods (75.3 ± 53.6 g/day) compared to the controls (110.7 ± 88.8 g/day). Logistic regression analyses showed that regular intake of soy foods could reduce the ovarian cancer risk, the adjusted odds ratio being 0.29 (95% confidence interval 0.20 to 0.42) for women who consumed at least 120 g/day relative to those less than 61 g/day. Similarly, isoflavone intakes were inversely associated with the ovarian cancer risk, with significant dose-response relationships (P < 0.001). We concluded that consumption of soy foods is associated with a reduced risk of ovarian cancer in southern Chinese women.

Dietary fat intake and risk of epithelial ovarian cancer by tumour histology

BACKGROUND

Studies of fat intake and epithelial ovarian cancer (EOC) risk have reported inconsistent findings, hence we hypothesised that associations may vary by histologic subtype.

METHODS

We evaluated fat intake in a New England case-control study including 1872 cases and 1978 population-based controls (1992-2008). Epithelial ovarian cancer risk factors and diet were assessed using a food frequency questionnaire at enrolment. Logistic regression was used to estimate associations between fat intake and EOC risk and polytomous logistic regression was used to test whether associations varied by histologic subtype.

RESULTS

We observed a decreased risk of EOC when comparing the highest vs lowest quartiles of intake of omega-3 (odds ratio (OR)=0.79, 95% confidence interval (CI) 0.66-0.96, P-trend=0.01) and omega-6 (OR=0.77, 95% CI 0.64-0.94, P-trend=0.02) and an increased risk with high consumption of trans fat (OR=1.30, 95% CI 1.08-1.57, P-trend=0.002). There was no significant heterogeneity by tumour histologic subtype; however, we observed a strong decreased risk for endometrioid invasive tumours with high intake of omega-3 (quartile (Q) 4 vs Q1, OR=0.58, 95% CI 0.41-0.82, P-trend=0.003).

CONCLUSIONS

These findings suggest that higher intake of omega-3 may be protective for EOC overall and endometrioid tumours in particular, whereas greater consumption of trans fat may increase risk of EOC overall.

Cruciferous vegetables consumption and the risk of ovarian cancer: a meta-analysis of observational studies

Background

To quantify the effect of cruciferous vegetable consumption on the incidence of ovarian cancer by meta-analyzing the existing observational studies and provides quantitative and high-level evidence.

Methods

A detailed literature search of Medline and EMBASE for all relevant papers published. A meta-analysis was conducted for the association between cruciferous vegetable consumption and risk of ovarian cancer.

Results

A total of 4,306 cases in 375,562 controls in 11 independent studies were identified in this current meta-analysis. The result of this current meta-analysis, including 6 case-control and 5 cohort studies, indicated that cruciferous vegetable intake was associated with a reduced risk of ovarian cancer. Cruciferous vegetable consumption was associated with a reduced risk of ovarian cancer in case-control studies (RR=0.84; 95% CI, 0.75-0.94) but not in cohort studies (RR=1.00; 95% CI, 0.85-1.11).

Conclusions

The results from this meta-analysis of observational studies demonstrate that cruciferous vegetable consumption is a prospective factor of the ovarian cancer. However, more in-depth studies are warranted to report more detailed results, including other specific vegetables within the cruciferous vegetable family.

Virtual slides

The virtual slide (s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1116708293115581.

Dietary phyto-oestrogens and the risk of ovarian and endometrial cancers: findings from two Australian case-control studies

Phyto-oestrogens have been suggested to have a protective effect on hormone-sensitive cancers. However, few studies have investigated the association between dietary phyto-oestrogens and gynaecological cancers. In the present study, we analysed data from two population-based case-control studies of ovarian (1366 cases and 1414 controls) and endometrial (1288 cases and 1435 controls) cancers. Dietary intake information was obtained using a 135-item FFQ, and phyto-oestrogen intake was estimated using published food composition databases. Unconditional logistic regression was used to estimate adjusted OR and 95% CI. In multivariable analyses, there was a suggestive pattern of inverse associations between increasing intakes of total phyto-oestrogens, isoflavones and enterolignans and the risk of ovarian cancer. However, the results only reached statistical significance for the lignan compounds matairesinol and lariciresinol, where the OR for the highest v. the lowest intake category was 0.72 (95% CI 0.54, 0.96; P for trend = 0.02) for matairesinol and 0.72 (95% CI 0.55, 0.96; P for trend = 0.03) for lariciresinol. When the risk of ovarian cancer was assessed by subtype, there was an indication that increasing intakes of phyto-oestrogens may be associated with a decreased risk of mucinous (cases n 158) ovarian tumours (OR for the highest v. the lowest intake category: 0.47 (95% CI 0.24, 0.93); P for trend = 0.04). However, there were no significant associations with other histological subtypes. In contrast, dietary phyto-oestrogens (total or any subclass) were unrelated to the risk of endometrial cancer cases overall or by subtype.