Dietary intakes of fat and fatty acids and risk of breast cancer: a prospective study in Japan

Association of saturated fatty acids with cancer risk: a systematic review and meta-analysis

OBJECTIVE

Extensive research has explored the link between saturated fatty acids (SFAs) and cardiovascular diseases, alongside other biological dysfunctions. Yet, their association with cancer risk remains a topic of debate among scholars. The present study aimed to elucidate this association through a robust meta-analysis.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science databases were searched systematically to identify relevant studies published until December 2023. The Newcastle-Ottawa Scale was used as the primary metric for evaluating the quality of the included studies. Further, fixed- or random-effects models were adopted to determine the ORs and the associated confidence intervals using the Stata15.1 software. The subsequent subgroup analysis revealed the source of detection and the cancer types, accompanied by sensitivity analyses and publication bias evaluations.

RESULTS

The meta-analysis incorporated 55 studies, comprising 38 case-control studies and 17 cohort studies. It revealed a significant positive correlation between elevated levels of total SFAs and the cancer risk (OR of 1.294; 95% CI: 1.182-1.416; P-value less than 0.001). Moreover, elevated levels of C14:0, C16:0, and C18:0 were implicated in the augmentation of the risk of cancer. However, no statistically significant correlation of the risk of cancer was observed with the elevated levels of C4:0, C6:0, C8:0, C10:0, C12:0, C15:0, C17:0, C20:0, C22:0, and C24:0. Subgroup analysis showed a significant relationship between excessive dietary SFA intake, elevated blood SFA levels, and heightened cancer risk. Increased total SFA levels correlated with higher risks of breast, prostate, and colorectal cancers, but not with lung, pancreatic, ovarian, or stomach cancers.

CONCLUSION

High total SFA levels were correlated with an increased cancer risk, particularly affecting breast, prostate, and colorectal cancers. Higher levels of specific SFA subtypes (C14:0, C16:0, and C18:0) are also linked to an increased cancer risk. The findings of the present study would assist in providing dietary recommendations for cancer prevention, thereby contributing to the development of potential strategies for clinical trials in which diet-related interventions would be used in combination with immunotherapy to alter the levels of SFAs in patients and thereby improve the outcomes in cancer patients. Nonetheless, further high-quality studies are warranted to confirm these associations.

Maternal lifestyle and nutrient intakes during pregnancy and exclusive breastfeeding in relation to risk factors for breast cancer: The Japan Environment and Children's Study

Breastfeeding has many benefits for infant growth and maternal health, such as reducing breast cancer risk. However, data on maternal factors influencing breastfeeding are insufficient. To clarify the associations between maternal lifestyle and diet during pregnancy and exclusive breastfeeding (EBF), we conducted a prospective study of pregnant women within the framework of the Japan Environment and Children's Study (a nationwide birth cohort study). Of 97,413 pregnant women recruited between January 2011 and March 2014, 27,775 with a singleton first live birth whose dietary data during pregnancy and lactation data were complete were eligible. Using logistic regression, we evaluated the associations between lifestyle factors including smoking and prepregnancy body mass index and intake of nutrients (macronutrients, isoflavones, and dietary fiber), some of which are known risk factors of breast cancer, and EBF for one month postpartum (initiation of EBF). To investigate the associations of these factors with EBF for 6 months (continuation of EBF), 9582 women who had successfully completed one-month EBF were further followed up. Smoking and prepregnancy obesity were inversely associated with the initiation and continuation of EBF. Intakes of protein, fat, isoflavone, and dietary fiber were positively associated (p _trend = 0.0001 for dietary fiber), and carbohydrate intake was inversely associated with the initiation of EBF. Dietary fiber intake was also associated with the continuation of EBF (p _trend = 0.048). These findings indicate that maternal lifestyles during pregnancy affect lactation performance. Lifestyle adjustments during pregnancy may have favorable effects on maternal and children's health through successful breastfeeding.

Breast cancer and dietary fat quality indices in Iranian women: A case-control study

Background

The association between breast cancer (BC) and different indices of dietary fats has not been well-studied. Thus, this study aimed to investigate the association between BC and dietary fat quality (DFQ) indices in Iranian women.

Methods

This case-control study was conducted on 120 women with breast cancer and 240 healthy women in Tehran, Iran. Food Frequency Questionnaire and nutritionist IV software were used to assess the intake of dietary fats and to calculate the DFQ indices.

Results

The patients with BC had a higher total fat (TF) (P < 0.01) and a lower ratio of polyunsaturated fatty acids (PUFAs) omega-3 to PUFAs omega-6 (ω-3/ω-6) compared with the controls (P < 0.001). TF had a significant association with BC risk (OR: 1.16; 95% CI: 1.01-1.33, P < 0.001). No significant association was found between BC and PUFA/saturated fatty acid ratio or the ω-3/ω-6 ratio.

Conclusion

The patients with BC had a lower ω-3/ω-6 ratio and a higher total dietary fat intake than the healthy women. Total dietary fat intake was also directly associated with the risk of BC. Thus, low-fat diets may have beneficial effects for BC prevention. Further longitudinal studies are warranted.

Association of dietary intake of n-3 polyunsaturated fatty acids with breast cancer risk in pre- and postmenopausal Chinese women

OBJECTIVE

This study aimed to evaluate the associations between breast cancer risk and intake of n-3 polyunsaturated fatty acids (PUFAs) and/or n-3 PUFA subclasses in Chinese women, and determine whether these associations varied with menopausal status or clinical characteristics.

METHODS

A hospital-based case-control study including 1,589 cases and 1,621 age-frequency-matched controls was conducted. Dietary data were assessed by a validated food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals were obtained using multiple unconditional logistic regression models after controlling for potential confounders.

RESULTS

Higher intake of marine n-3 PUFAs and total n-3 PUFAs was associated with lower risk of breast cancer, with adjusted OR quartile 4 v.1 (95% confidence intervals) of 0.68 (0.55-0.84) and 0.56 (0.42-0.75), respectively. Dietary a-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid were also inversely associated with breast cancer risk, with adjusted ORs (95% confidence intervals) of 0.51 (0.38-0.70), 0.68 (0.55-0.84), 0.68 (0.55-0.85), and 0.76 (0.61-0.94), respectively. In stratified analyses, these inverse associations between risk and dietary n-3 PUFAs were more evident among premenopausal women and women with ER+, PR+ and ER+PR+ tumors. A decreased risk of breast cancer was significantly associated with increasing n-3 PUFA intake in obese/overweight women, but not in women of normal weight. There was a significant interaction between linoleic acid and marine n-3 PUFAs.

CONCLUSIONS

High intake of n-3 PUFAs and n-3 PUFA subtypes was associated with a lower risk of breast cancer, especially among premenopausal women and women with ER+ and/or PR+ subtype breast cancer.

Interconnected Clinical and Social Risk Factors in Breast Cancer and Heart Failure

Breast cancer and heart failure share several known clinical cardiovascular risk factors, including age, obesity, glucose dysregulation, cholesterol dysregulation, hypertension, atrial fibrillation and inflammation. However, to fully comprehend the complex interplay between risk of breast cancer and heart failure, factors attributed to both biological and social determinants of health must be explored in risk-assessment. There are several social factors that impede implementation of prevention strategies and treatment for breast cancer and heart failure prevention, including socioeconomic status, neighborhood disadvantage, food insecurity, access to healthcare, and social isolation. A comprehensive approach to prevention of both breast cancer and heart failure must include assessment for both traditional clinical risk factors and social determinants of health in patients to address root causes of lifestyle and modifiable risk factors. In this review, we examine clinical and social determinants of health in breast cancer and heart failure that are necessary to consider in the design and implementation of effective prevention strategies that altogether reduce the risk of both chronic diseases

A Prospective Analysis of Plasma Phospholipid Fatty Acids and Breast Cancer Risk in 2 Provinces in Canada

BACKGROUND

Studies suggest that fatty acid status influences breast cancer etiology, yet the roles of individual fatty acids in breast cancer risk are unclear, specifically when central adiposity and menopausal status are considered.

OBJECTIVES

This study examined the associations of fatty acid status with breast cancer risk including location, menopausal status, and waist-to-hip ratio as key variables.

METHODS

Prediagnostic plasma phospholipid fatty acids were measured in women with breast cancer (n = 393) and age-matched controls (n = 786) from a nested case-control prospective study within Alberta's Tomorrow Project (ATP) and British Columbia Generations Project (BCGP) cohorts. Binary logistic regression models were used to evaluate associations of fatty acids and breast cancer risk with subgroup analysis for menopausal status and waist-to-hip ratio.

RESULTS

Women from BCGP had a higher n-3 (ɷ-3) fatty acid status compared with the ATP (6.4% ± 0.08% vs. 5.3% ± 0.06%; P < 0.001), so subsequent analysis was blocked by cohort. Overall, fatty acids had inconsistent associations with risk. In the ATP among premenopausal women, total long-chain n-3 fatty acids (ORQ4vsQ1 = 1.78; 95% CI: 0.58, 5.43; P-trend = 0.007, P-interaction = 0.07) were positively associated with breast cancer risk, whereas in BCGP, DHA (ORQ4vsQ1 = 0.66; 95% CI: 0.28, 1.53; P-trend = 0.03, P-interaction = 0.05) and total long-chain n-3 fatty acids (ORQ4vsQ1 = 0.66; 95% CI: 0.28, 1.54; P-trend = 0.03) were associated with decreased cancer risk when the waist-to-hip ratio was <0.85.

CONCLUSIONS

Our findings suggest that regional variations in fatty acid status influence breast cancer risk, resulting in positive associations of total long-chain n-3 fatty acids in premenopausal ATP women and negative associations of these fatty acids in BCGP women with a waist-to-hip ratio below guidelines. This study highlights the complexity and difficulty in using fatty acid status to predict breast cancer risk in diverse populations without the consideration of other risk factors.

Serum fatty acid synthase levels and n-3 fatty acid intake in patients with breast cancer

PURPOSE

Fatty acid synthase (FASN) is a key enzyme in fatty acid biosynthesis that is usually over-expressed in patients with breast cancer, but its relationship with the patient's dietary habit is not clear. A higher intake of n-3 polyunsaturated fatty acids is related to reduced breast carcinogenesis in vitro and in vivo. The aim of this study was to clinically investigate the association between serum FASN levels and fatty acid intake in women newly diagnosed with breast cancer.

METHODS

In a case-control cross-sectional study, with 18 breast cancer patients and 29 controls, we evaluated nutritional status, dietary intake, and serum FASN levels. Statistical analyses were carried out with parametric and non-parametric tests, according to the sample's normality distribution.

RESULTS

The mean age of breast cancer group (n = 18) and control group (n = 29) was 46.8 ± 9.7 y and 44.4. ± 8.6 y, respectively. Mean serum concentration of FASN in breast cancer group was significantly higher (132.51 ± 95.05 ng/mL) than in control group (36.88 ± 20.87 ng/mL) (p < 0.0001). Among breast cancer group, serum FASN levels of premenopausal women were significantly higher than those of postmenopausal women (p = 0.026). There was no significant difference between the early and late disease stages in regard to serum FASN levels in breast cancer group. Mean nutrient intake was similar and n-3 docosahexaenoic acid intake was low in both groups. We observed no association regarding fatty acid intake and serum FASN levels.

CONCLUSION

These data suggest that dietary n-3 fatty acid has no association with serum FASN levels among newly diagnosed breast cancer patients.

Fatty acid binding protein 7 mediates linoleic acid-induced cell death in triple negative breast cancer cells by modulating 13-HODE

Different fatty acids have distinct effects on the survival of breast cancer cells, which could be mediated by fatty acid binding proteins (FABPs), a family of lipid chaperones. Due to the diverse structures of the members of FABP family, each FABP demonstrates distinct binding affinities to different fatty acids. Of note, FABP7 is predominantly expressed in triple negative breast cancer (TNBC), the most aggressive subtype of breast cancer. Yet, the role of FABP7 in modulating the effects of fatty acids on TNBC survival was unclear. In contrast to the high expression of FABP7 in human TNBC tumours, FABP7 protein was undetectable in TNBC cell lines. Hence, a FABP7 overexpression model was used for this study, in which the transduced TNBC cell lines (MDA-MB-231 and Hs578T) were treated with various mono- and polyunsaturated fatty acids. Oleic acid (OA), docosahexaenoic acid (DHA) and arachidonic acid (AA) inhibited TNBC cell growth at high concentrations, with no differences resulted from FABP7 overexpression. Interestingly, overexpression of FABP7 augmented linoleic acid-induced cell death in MDA-MB-231 cells. The increased cell death may be explained by a decrease in 13-HODE, a pro-tumorigenic oxidation product of linoleic acid. The phenotype was, however, attenuated with a rescue treatment using 25 nM 13-HODE. The decrease in 13-HODE was potentially due to fatty acid partitioning modulated by FABP7, as demonstrated by a 3-fold increase in fatty acid oxidation. Our findings suggest that linoleic acid could be a potential therapeutic strategy for FABP7-overexpressing TNBC patients.

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.

Multi-Grain Rice Diet Decreases Risk of Breast Cancer in Korean Women: Results from the Health Examinees Study

Although a number of studies explain the association between dietary patterns, which take into account that foods are eaten in combination, and breast cancer risk, the findings are inconsistent. We examined the association between dietary patterns and multi-grain rice intake, and the risk of breast cancer in a large-scale prospective cohort study in Korean women. A total of 93,306 women aged 40–69 years from the Health Examinees-Gem (HEXA-G) study (2004 and 2013) were included. We obtained Information on cancer diagnosis via linkage to the Korea Central Cancer Registry. Factor analysis was conducted to obtain dietary patterns, and Cox proportional models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CI) for breast cancer risk. For 494,490 person-years, 359 new cases of breast cancer occurred. We identified three major dietary patterns, that explained 23.9% of the total variance based on daily total food intake (g/day) from 37 food groups: the meat dietary pattern (higher intake of bread and red meat), the white rice dietary pattern (higher intake of white rice and lower intake of multi-grain rice), and the other pattern. Women who had higher white rice dietary pattern scores had a 35% higher risk of breast cancer, than did women with lower white rice dietary pattern scores (multivariable HR 1.35; 95% CI 1.00–1.84 for the highest vs. lowest quartile of the white rice dietary pattern scores, p for trend = 0.0384). We found that women who consumed three or more servings of multi-grain rice per day had 33% lower risk of breast cancer than did those who consumed one or less multi-grain rice serving per day among women under 50 years of age (multivariable HR 0.67; 95% CI 0.45–0.99, p for trend = 0.0204). Our study suggests that a multi-grain rice diet may be associated with lower risk of breast cancer in Korean women.

Dietary Intake of N-3 and N-6 Polyunsaturated Fatty Acids and Risk of Cancer: Meta-Analysis of Data from 32 Studies

BACKGROUND

Large epidemiological studies have yielded conflicting results regarding the relationship between polyunsaturated fatty acids (PUFAs) and cancers. Here, we performed a meta-analysis to examine the link between dietary intake of n-3 and n-6 PUFAs and cancer risk.

MATERIALS AND METHODS

We performed a search on PubMed, EMBASE, and the Cochrane Library. Studies that reported adjusted relative risk (RR) estimates with 95% confidence intervals (CI) for the associations of interest were included.

RESULTS

Thirty-two studies involving 1,445,732 participants were included. Colorectal, breast and prostate cancer had been analyzed in our study. Specifically, for colorectal cancer, total n-3 PUFAs, marine n-3 PUFAs, α-linolenic acids (ALA) and n-6 PUFAs were not associated with the risk of it (RR 1.04, 95%CI 0.85-1.28; RR 0.99, 95%CI 0.89-1.09; RR 1.05, 95%CI 0.93-1.19; RR 1.02, 95%CI 0.94-1.11, respectively). For breast cancer, only marine n-3 PUFAs, but not total n-3 PUFAs, ALA, and n-6 PUFAs, was associated with a lower risk of it (RR 0.70, 95%CI 0.55-0.91). For prostate cancer, ALA and n-6 PUFAs also have no association with the risk of it.

CONCLUSIONS

Most subtypes of PUFAs are probably not related to cancers. However, additional high-quality trials are warranted to corroborate the findings of this meta-analysis.

Impact of 17β-HSD12, the 3-ketoacyl-CoA reductase of long-chain fatty acid synthesis, on breast cancer cell proliferation and migration

Metabolic reprogramming of tumor cells involves upregulation of fatty acid (FA) synthesis to support high bioenergetic demands and membrane synthesis. This has been shown for cytosolic synthesis of FAs with up to 16 carbon atoms. Synthesis of long-chain fatty acids (LCFAs), including ω-6 and ω-3 polyunsaturated FAs, takes place at the endoplasmic reticulum. Despite increasing evidence for an important role of LCFAs in cancer, the impact of their synthesis in cancer cell growth has scarcely been studied. Here, we demonstrated that silencing of 17β-hydroxysteroid dehydrogenase type 12 (17β-HSD12), essentially catalyzing the 3-ketoacyl-CoA reduction step in LCFA production, modulates proliferation and migration of breast cancer cells in a cell line-dependent manner. Increased proliferation and migration after 17β-HSD12 knockdown were partly mediated by metabolism of arachidonic acid towards COX2 and CYP1B1-derived eicosanoids. Decreased proliferation was rescued by increased glucose concentration and was preceded by reduced ATP production through oxidative phosphorylation and spare respiratory capacity. In addition, 17β-HSD12 silencing was accompanied by alterations in unfolded protein response, including a decrease in CHOP expression and increase in eIF2α activation and the folding chaperone ERp44. Our study highlights the significance of LCFA biosynthesis for tumor cell physiology and unveils unknown aspects of breast cancer cell heterogeneity.

Low-Level Saturated Fatty Acid Palmitate Benefits Liver Cells by Boosting Mitochondrial Metabolism via CDK1-SIRT3-CPT2 Cascade

Saturated fatty acids (SFAs) (the "bad" fat), especially palmitate (PA), in the human diet are blamed for potential health risks such as obesity and cancer because of SFA-induced lipotoxicity. However, epidemiological results demonstrate a latent benefit of SFAs, and it remains elusive whether a certain low level of SFAs is physiologically essential for maintaining cell metabolic hemostasis. Here, we demonstrate that although high-level PA (HPA) indeed induces lipotoxic effects in liver cells, low-level PA (LPA) increases mitochondrial functions and alleviates the injuries induced by HPA or hepatoxic agent carbon tetrachloride (CCl₄). LPA treatment in mice enhanced liver mitochondrial activity and reduced CCl₄ hepatotoxicity with improved blood levels of aspartate aminotransferase (AST), alanine transaminase (ALT), and mitochondrial aspartate transaminase (m-AST). LPA-mediated mitochondrial homeostasis is regulated by CDK1-mediated SIRT3 phosphorylation, which in turn deacetylates and dimerizes CPT2 to enhance fatty acid oxidation. Thus, an advantageous effect is suggested by the consumption of LPA that augments mitochondrial metabolic homeostasis via CDK1-SIRT3-CPT2 cascade.

Docosahexaenoic Acid Inhibits PTP1B Phosphatase and the Viability of MCF-7 Breast Cancer Cells

BACKGROUND

Docosahexaenoic acid (DHA) is an essential polyunsaturated fatty acid compound present in deep water fishes and dietary supplements, with a wide spectrum of potential health benefits, ranging from neurological to anti-inflammatory.

METHODS

Due to the fact that DHA is considered a breast cancer risk reducer, we examined the impact of DHA on MCF-7 breast cancer cells' viability and its inhibitory properties on protein tyrosine phosphatase 1B (PTP1B), a pro-oncogenic phosphatase.

RESULTS

We found that DHA is able to lower both the enzymatic activity of PTP1B phosphatase and the viability of MCF-7 breast cancer cells. We showed that unsaturated DHA possesses a significantly higher inhibitory activity toward PTP1B in comparison to similar fatty acids. We also performed a computational analysis of DHA binding to PTP1B and discovered that it is able to bind to an allosteric binding site.

CONCLUSIONS

Utilizing both a recombinant enzyme and cellular models, we demonstrated that DHA can be considered a potential pharmacological agent for the prevention of breast cancer.

Breast cancer prevention in premenopausal women: role of the Mediterranean diet and its components

Breast cancer (BC) is a growing public health concern in most developed and developing countries. Since an increasing number of patients with BC are diagnosed before the menopause and premenopausal women show a more aggressive phenotype, there is consistent interest in promoting prevention strategies in order to reduce the incidence of BC in the premenopause. The Mediterranean diet (MD) has been reported to have beneficial effect in terms of cancer prevention. This healthy dietary pattern consists primarily of foods having important antioxidant properties along with a favourable fatty acid profile, all associated with a reduced risk of cancer. Due to the large variability in study subject characteristics, the protective role of the MD on BC still remains controversial and studies that have investigated the association between adherence to the MD and risk of BC in premenopausal women are fewer than those in postmenopausal women. In addition, the possibility that the beneficial effects of the MD are due to a single component or might more probably derive from the synergic effects of all components of the MD remains a scantly explored field. Considering the increased risk of recurrence and mortality rate of BC in premenopausal women as compared with postmenopausal women, the aim of the present report is to provide a general overview of the current evidence on the relationship between BC and the MD specifically in premenopausal women, and to emphasise the potential role of the MD as an effective measure to reduce the risk of developing BC in premenopausal women.

Healthy dietary patterns and risk and survival of breast cancer: a meta-analysis of cohort studies

PURPOSES

Dietary patterns have been found to be associated with the overall cancer risk and survival. However, the associations of healthy dietary patterns and breast cancer remain unclear. We aimed to conduct a meta-analysis of prospective cohort studies to estimate the pooled results of the association of healthy dietary patterns with breast cancer risk and survival.

METHODS

PubMed, EMBASE, and Web of Science were searched for literature published until June 24th, 2018 that examined the associations between healthy dietary patterns and breast cancer risk and survival. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated by using a random-effects model for meta-analysis.

RESULTS

There were 32 articles retrieved for the meta-analysis, with 27 for breast cancer risk and five for breast cancer survival. There was a statistically significant lower risk of breast cancer associated with healthy dietary patterns (RR = 0.93, 95% CI: 0.88, 0.98). Subgroup analysis results suggested that there was an inverse association between breast cancer risk and posterori-derived healthy patterns, but no statistically significant associations were found in other stratified subgroups (a priori-derived diet, study region, menopausal status, or breast cancer subtypes). Healthy dietary patterns were associated inversely with all-cause mortality (RR = 0.76, 95% CI: 0.63, 0.92); however, no association was found for breast cancer-specific mortality.

CONCLUSIONS

The results suggested that healthy dietary patterns might be associated with a reduced risk of breast cancer and all-cause mortality among breast cancer patients. It could be clinically relevant to promote healthy dietary patterns for breast cancer prevention and improve survival among breast cancer patients.

Association of Dietary Intake Ratio of n-3/n-6 Polyunsaturated Fatty Acids with Breast Cancer Risk in Western and Asian Countries: A Meta-Analysis

Objective:

This systematic review and meta-analysis were performed to determine association of dietary intake ratio of n-3/n-6 polyunsaturated fatty acids with breast cancer risk in Western and Asian countries.

Methods:

The authors conducted a meta-analysis of published research articles on association of dietary intake ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs) with breast cancer risk in Western and Asian countries published between January 2000 and February 2019 in online article databases of PubMed, ProQuest and EBSCO. Pooled risk ratios (RR) were calculated using fixed and random-effect models. Publication bias was visually evaluated by performing funnel plots and statistically assessed by Egger’s and Begg’s tests. Data were processed by using Stata version 14.2 (Stata Corporation).

Results:

This study reviewed 913 articles. There were 13 studies included in systematic review continued by meta-analysis of relevant data with total number of samples: 275,264 patients. The results showed dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Western and Asian countries (RR = 0.99; 95%CI: 0.92-1.07). Dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Western countries reached (RR = 0.98; 95%CI: 0.91-1.06) and there was any significant publication bias for studies included. Dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Asian countries reached (RR = 1.18; 95%CI: 0.94-1.47) and there was not any significant publication bias for studies included.

Conclusion:

This analysis confirmed association of dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Western and Asian countries. Higher dietary intake ratio is associated with lower risk of breast cancer in Asian countries rather than Western countries. This study suggests increasing dietary intake ratio n-3/n-6 PUFAs will provide benefit for breast cancer prevention.

Television Viewing Time and Breast Cancer Incidence for Japanese Premenopausal and Postmenopausal Women: The JACC Study

Purpose

The evidence on effects of TV viewing time among premenopausal and postmenopausal women for breast cancer risk remains controversial and limited.

Materials and Methods

A prospective study encompassing 33,276 (17,568 premenopausal, and 15,708 postmenopausal) women aged 40-79 years in whom TV viewing time, menstrual, and reproductive histories were determined by a self-administered questionnaire. The follow-up was from 1988 to 2009 and hazard ratios (HRs) with 95% confidence intervals (CIs) of breast cancer incidence were calculated for longer TV viewing time in reference to shorter TV viewing time by Cox proportional hazard models.

Results

During 16.8-year median follow-up, we found positive associations between TV viewing time and breast cancer incidence with a borderline significant trend among total women and a significant trend among postmenopausal women. Among total women, the multivariable HRs (95% CIs) for risk of breast cancer in reference to < 1.5 hr/day of TV viewing time were 0.89 (0.59-1.34) for 1.5 to < 3.0 hr/day, 1.19 (0.82-1.74) for 3.0 to < 4.5 hr/day, and 1.45 (0.91-2.32) for ≥ 4.5 hr/day (p for trend=0.053) and among postmenopausal women, the corresponding risk estimates were 1.10 (0.42-2.88), 2.54 (1.11-5.80), and 2.37 (0.92-6.10) (p for trend=0.009), respectively.

Conclusion

Prolonged TV viewing time was associated with increased risk of breast cancer, especially among postmenopausal women.

Protective Effect of Omega-3 Fatty Acids in Fish Consumption Against Breast Cancer in Asian Patients: A Meta-Analysis

Objective:

This systematic review and meta-analysis was performed to determine the protective effect of omega-3 fatty acids in fish consumption against breast cancer in Asian patients.

Methods:

The authors conducted a meta-analysis of published research articles on protective effect of omega-3 fatty acids in fish consumption against breast cancer in Asian patients published between January 2000 and July 2018 in online database of PubMed, ProQuest and EBSCO. Pooled odds ratios (OR) were calculated by using fixed and random-effect models. Publication bias was visually evaluated by using funnel plots and statistically assessed in Egger’s and Begg’s tests. Data were processed by Review Manager 5.3 (RevMan 5.3) and Stata version 14.2 (Stata Corporation).

Results:

This study reviewed 913 articles. There were 11 studies which conducted systematic review then continued by meta-analysis of relevant data with total number of samples were 130,365 patients. The results showed there was protective effect of omega-3 fatty acids in fish consumption against breast cancer in Asian patients (OR = 0.80 [95% CI 0.73-0.87, p <0.00001]). There was not any study with significant publication bias included.

Conclusion:

This analysis confirmed the protective effect of omega-3 fatty acids in fish consumption against breast cancer in Asian patients.

Dietary patterns and breast cancer risk among Iranian women: A case-control study

AIM

Breast cancer is the most common cancer among women worldwide. Most previous studies focused on individual nutrients or foods rather than overall dietary patterns. We aimed to assess the association between major dietary patterns and breast cancer risk.

METHOD

In a hospital-based case-control study, 134 women diagnosed as breast cancer and 267 controls were recruited from referral hospitals in Tehran, Iran. Dietary intakes were evaluated by using a validated 168-item food frequency questionnaire. Dietary pattern were identified by factor analysis. Odds ratios (OR) were estimated using logistic regression.

RESULTS

Two dietary patterns were extracted: healthy and unhealthy. The "Healthy" dietary pattern was loaded for high consumptions of fruits, vegetables, seeds, legume, fish and sea foods, whole grains, liquid oils, olive oils and olive and lack of salt intake. "Unhealthy" dietary pattern was characterized by high factor loadings for sweets, soft drinks, mayonnaise, solid oils, processed meat, fried and boiled potato and salt intake. In multivariate logistic regression analyses, the healthy dietary pattern was not associated with breast cancer risk (OR: 0.83; 95%CI: 0.36, 1.89; P-trend = 0.50), while women in the highest quartile of the unhealthy dietary pattern had a significantly increased breast cancer risk (OR: 2.21; 95%CI: 1.04, 4.690; P-trend = 0.009). When stratified by menopausal status, unhealthy dietary pattern showed inverse association with breast cancer risk only among post-menopausal women (OR: 3.56; 95%CI: 1.16, 10.95; P-trend = 0.008).

CONCLUSIONS

Our findings showed that an unhealthy dietary pattern might be associated with higher risk of breast among Iranian women.

Cardiovascular Disease and Breast Cancer: Where These Entities Intersect: A Scientific Statement From the American Heart Association

Cardiovascular disease (CVD) remains the leading cause of mortality in women, yet many people perceive breast cancer to be the number one threat to women's health. CVD and breast cancer have several overlapping risk factors, such as obesity and smoking. Additionally, current breast cancer treatments can have a negative impact on cardiovascular health (eg, left ventricular dysfunction, accelerated CVD), and for women with pre-existing CVD, this might influence cancer treatment decisions by both the patient and the provider. Improvements in early detection and treatment of breast cancer have led to an increasing number of breast cancer survivors who are at risk of long-term cardiac complications from cancer treatments. For older women, CVD poses a greater mortality threat than breast cancer itself. This is the first scientific statement from the American Heart Association on CVD and breast cancer. This document will provide a comprehensive overview of the prevalence of these diseases, shared risk factors, the cardiotoxic effects of therapy, and the prevention and treatment of CVD in breast cancer patients.

Macronutrient intakes and serum oestrogen, and interaction with polymorphisms in CYP19A1 and HSD17B1 genes: a cross-sectional study in postmenopausal Japanese women

Although higher circulating levels of oestrogen are related to postmenopausal breast cancer risk, limited information is available regarding effects of diet on endogenous oestrogen. Thus, we examined associations between macronutrient intakes and serum oestrogen with consideration of polymorphisms in oestrogen-metabolising genes. In this cross-sectional study, 784 naturally menopaused Japanese women aged 47–69 years were selected from participants of the Japan Multi-Institutional Collaborative Cohort Study. We documented dietary intakes, measured serum concentrations of oestrone (E1) and oestradiol (E2) and genotyped polymorphisms in oestrogen-metabolising CYP19A1 (rs4441215 and rs936306) and HSD17B1 (rs605059) genes. Trends and interactions were examined using linear regression models. In addition, we calculated the ratios of the oestrogen concentrations of the second to the highest quartiles (Q2–Q4) of dietary intake to those of the lowest quartiles (Q1). After adjustment for potential confounders, E2 was significantly associated with intake of carbohydrate and noodles; ratios of Q4 v. Q1 were 1·15 (95 % CI 1·04, 1·28) and 1·15 (95 % CI 1·04, 1·26), respectively. In contrast, E2 levels were inversely associated with intake of total energy, SFA and n-3 highly unsaturated fatty acids (n-3 HUFA); ratios of Q4 v. Q1 were 0·90 (95 % CI 0·82, 0·99), 0·89 (95 % CI 0·81, 0·98) and 0·91 (95 % CI 0·83, 1·00), respectively. In stratified analysis by polymorphisms, the rs605059 genotype of HSD17B1 significantly modified associations of E2 with intake of n-3 HUFA and fish; the associations were limited to those with the CC genotype. Macronutrient intakes were associated with serum E2 level, and these associations may be modified by HSD17B1 polymorphism in postmenopausal women.

Omega-3 free fatty acids attenuate insulin-promoted breast cancer cell proliferation

High insulin levels in obese people are considered as a risk factor to induce breast carcinogenesis. And consumption of fish oils which mainly contain omega-3 fatty acids is associated with a reduced risk of breast cancer. However, whether omega-3 free fatty acids (FFAs) modulate insulin signaling pathway to prevent breast cancer is poorly understood. The current study tested the hypothesis that omega-3 FFAs attenuate insulin-induced breast cancer cell proliferation and regulate insulin signaling pathway. We show here that omega-3 FFAs attenuate MCF-7 cell proliferation and Akt and Erk1/2 phosphorylation levels stimulated by insulin. Knockdown Shp2 by siRNA resulted in significantly elevated omega-3 FFAs-activated Akt phosphorylation but failed to change insulin-stimulated Akt and Erk1/2 phosphorylation. And viable cell number was not affected by either downregulation of Shp2 expression or Erk1/2 inhibitor U0126 treatment. These observations indicated that omega-3 FFAs attenuate insulin-promoted breast cancer cell proliferation and insulin-activated Akt phosphorylation.

Dietary Protein Sources and Incidence of Breast Cancer: A Dose-Response Meta-Analysis of Prospective Studies

Protein is important to the human body, and different sources of protein may have different effects on the risk of breast cancer. Thus, we conducted a meta-analysis to investigate the association between different dietary protein sources and breast cancer risk. PubMed and several databases were searched until December 2015. Relevant articles were retrieved according to specific searching criteria. Forty-six prospective studies were included. The summary relative risk (RR) for highest versus lowest intake was 1.07 (95% confidence interval (CI) 1.01-1.14, I² = 34.6%) for processed meat, 0.92 (95% CI 0.84-1.00, I² = 0%) for soy food, 0.93 (95% CI 0.85-1.00, I² = 40.1%) for skim milk, and 0.90 (95% CI 0.82-1.00, I² = 0%) for yogurt. Similar conclusions were obtained in dose-response association for each serving increase: total red meat (RR: 1.07; 95% CI 1.01-1.14, I² = 7.1%), fresh red meat (RR: 1.13; 95% CI 1.01-1.26, I² = 56.4%), processed meat (RR: 1.09; 95% CI 1.02-1.17, I² = 11.8%), soy food (RR: 0.91; 95% CI 0.84-1.00, I² = 0%), and skim milk (RR: 0.96; 95% CI 0.92-1.00, I² = 11.9%). There was a null association between poultry, fish, egg, nuts, total milk, and whole milk intake and breast cancer risk. Higher total red meat, fresh red meat, and processed meat intake may be risk factors for breast cancer, whereas higher soy food and skim milk intake may reduce the risk of breast cancer.

Role of n-3 Polyunsaturated Fatty Acids and Exercise in Breast Cancer Prevention: Identifying Common Targets

Diet and exercise are recognized as important lifestyle factors that significantly influence breast cancer risk. In particular, dietary n-3 polyunsaturated fatty acids (PUFAs) have been shown to play an important role in breast cancer prevention. Growing evidence also demonstrates a role for exercise in cancer and chronic disease prevention. However, the potential synergistic effect of n-3 PUFA intake and exercise is yet to be determined. This review explores targets for breast cancer prevention that are common between n-3 PUFA intake and exercise and that may be important study outcomes for future research investigating the combined effect of n-3 PUFA intake and exercise. These lines of evidence highlight potential new avenues for research and strategies for breast cancer prevention.

The Role of Docosahexaenoic Acid (DHA) in the Control of Obesity and Metabolic Derangements in Breast Cancer

Obesity represents a major under-recognized preventable risk factor for cancer development and recurrence, including breast cancer (BC). Healthy diet and correct lifestyle play crucial role for the treatment of obesity and for the prevention of BC. Obesity is significantly prevalent in western countries and it contributes to almost 50% of BC in older women. Mechanisms underlying obesity, such as inflammation and insulin resistance, are also involved in BC development. Fatty acids are among the most extensively studied dietary factors, whose changes appear to be closely related with BC risk. Alterations of specific ω-3 polyunsaturated fatty acids (PUFAs), particularly low basal docosahexaenoic acid (DHA) levels, appear to be important in increasing cancer risk and its relapse, influencing its progression and prognosis and affecting the response to treatments. On the other hand, DHA supplementation increases the response to anticancer therapies and reduces the undesired side effects of anticancer therapies. Experimental and clinical evidence shows that higher fish consumption or intake of DHA reduces BC cell growth and its relapse risk. Controversy exists on the potential anticancer effects of marine ω-3 PUFAs and especially DHA, and larger clinical trials appear mandatory to clarify these aspects. The present review article is aimed at exploring the capacity of DHA in controlling obesity-related inflammation and in reducing insulin resistance in BC development, progression, and response to therapies.

Dietary patterns and breast cancer risk in a prospective Japanese study

BACKGROUND

The association between dietary patterns and breast cancer has been inconsistent.

METHODS

This study examined associations between dietary patterns and risk of developing breast cancer among 23,172 women from the Japan Collaborative Cohort Study, including 119 incidences of breast cancer diagnosed during a median 16.9-year follow-up period. Factor analysis was conducted to obtain dietary patterns, and Cox proportional models were used to estimate hazard ratios (HR) and 95 % confidence intervals (95 % CI) for breast cancer morbidity.

RESULTS

Three dietary patterns were identified: ''vegetable pattern'' (vegetables, potatoes, seaweed, tofu, fruits, fresh fish, eggs, and miso soup); ''animal food pattern'' (meat, deep-fried foods, fried vegetables, fish paste and salt-preserved fish); and "dairy product pattern'' (milk, dairy products, fruits, coffee and tea). After adjusting for potential confounders, the vegetable and dairy product patterns were not significantly associated with risk of breast cancer. However, the animal food pattern was significantly associated with a decreased risk of breast cancer morbidity among premenopausal women by HR 0.47 for the 2nd tertile (95 % CI 0.22-1.00) and HR 0.42 for the 3rd tertile (95 % CI 0.18-0.93), compared with the bottom tertile (p for trend 0.04).

CONCLUSION

We found no significant association between the vegetable and dairy product dietary patterns and breast cancer risk; however, an animal product diet may reduce risk of breast cancer among premenopausal Japanese women.

Dietary total fat and fatty acids intake, serum fatty acids and risk of breast cancer: A meta-analysis of prospective cohort studies

Results from prospective cohort studies on the association between dietary total fat and fatty acids intake and risk of breast cancer remain controversial. Pertinent prospective cohort studies were identified by a search of Embase and PubMed from inception to September 2015. Study-specific relative risks (RRs) with 95% confidence intervals were pooled using a random-effect model. Between-study heterogeneity and publication bias were assessed, and sensitivity analysis was conducted. Twenty-four independent studies on dietary total fat and fatty acids intake and seven studies on serum fatty acids were included. The pooled RR of breast cancer for the highest vs. lowest category of dietary total fat intake was 1.10 (1.02-1.19); however, no association was observed in studies adjusting for traditional risk factors of breast cancer. No association was observed between animal fat, vegetable fat, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), n-3 PUFA, n-6 PUFA, eicosapentaenoic acid, docosahexaenoic acid, alpha-linolenic acid, oleic acid, linoleic acid and arachidonic acid and risk of breast cancer. The pooled RRs of breast cancer for the highest vs. lowest category of serum SFA, MUFA, PUFA, n-3 PUFA and n-6 PUFA were 1.00 (0.78-1.28), 1.41 (0.99-2.03), 0.59 (0.27-1.30), 0.81 (0.60-1.10) and 0.84 (0.60-1.18), respectively. Results from this meta-analysis suggested that dietary total fat and fatty acids might be not associated with risk of breast cancer.

Meta-Analysis of Saturated Fatty Acid Intake and Breast Cancer Risk

The associations between saturated fatty acid (SFA) consumption and risk of breast cancer (BC) remains inconclusive. Therefore, we conducted this meta-analysis to determine the quantitative relations between dietary SFA intake and incidence of BC.Literatures published up to April 2015 were systematically screened through Pubmed and Web of Science. Relevant publication quality was evaluated by conducting the Newcastle-Ottawa scale. We used fixed effects models or random effect models to calculate the summary relative risks (RRs) and odds ratios (ORs), and conducted sensitivity analyses and evaluated the publication bias.We identified a total of 52 studies (24 cohort studies and 28 case-control studies), with over 50,000 females diagnosed with BC. The associations between dietary SFA intake and risk of BC were 1.18 for case-control studies (high vs low intake, 95% confidence interval [CI] = 1.03-1.34) and 1.04 for cohort studies (95% CI = 0.97-1.11). When restricted analyses to population-based studies, positive associations were observed for both cohort (RR [95% CI] = 1.11 [1.01-1.21]) and case-control studies (OR [95% CI] = 1.26 [1.03-1.53]). Additionally, for case-control studies, significant positive associations between higher SFA intake and BC risk were observed for Asian (OR [95% CI] = 1.17 [1.02-1.34]) and Caucasian (OR [95% CI] = 1.19 [1.00-1.41]), as well as for postmenopausal women (OR = 1.33, 95% CI: 1.02-1.73). In contrast, higher dietary SFA intake was not associated with risk of BC among premenopausal women, in cohort studies or hospital-based studies.A positive association between higher dietary SFA intake and postmenopausal BC risk was observed in case-control but not in cohort studies. More studies are warranted to confirm these findings.

Adherence to the World Cancer Research Fund/American Institute for Cancer Research cancer prevention recommendations and breast cancer risk in the Cancer de Màma (CAMA) study

OBJECTIVE

We investigated the association between adherence to the recommendations of the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) and breast cancer (BC) risk in the Cancer de Màma (CAMA) study in a Mexican population.

DESIGN

Population-based case-control study.

SUBJECTS

Incident BC cases (n 1000) and controls (n 1074) matched on age, region and health-care system were recruited.

SETTING

In-person interviews were conducted to assess BC risk factors and habitual diet was assessed with an FFQ. Conformity to the WCRF/AICR recommendations was evaluated through a score incorporating seven WCRF/AICR components (body fatness, physical activity, foods and drinks that promote weight gain, plant foods, animal foods, alcoholic drinks and breast-feeding), with high scores indicating adherence to the WCRF/AICR recommendations.

RESULTS

No statistically significant associations between WCRF/AICR score and risk of BC were observed. After excluding BMI from the WCRF/AICR score, the top quartile was associated with a decreased BC risk overall, with ORQ4-Q1=0.68 (95% CI 0.49, 0.92, P trend=0.03), and among postmenopausal women, with ORQ4-Q1=0.60 (95% CI 0.39, 0.94, P trend=0.03). Inverse associations were observed between BMI and risk of BC overall and among premenopausal women, with OR=0.57 (95% CI 0.42, 0.76, P trend <0.01) and 0.48 (95% CI 0.31, 0.73, P trend<0.01), respectively. Physical activity level was inversely associated with BC risk.

CONCLUSIONS

The WCRF/AICR index was not related with BC risk in the CAMA study. A combination of six components excluding BMI showed strong protective associations, particularly in postmenopausal women. Further prospective studies are required to clarify the role of adherence to WCRF/AICR recommendations, particularly with respect to BMI, in the Mexican population.

Polyunsaturated fatty acid interactions and breast cancer incidence: a population-based case-control study on Long Island, New York

PURPOSE

Experimental studies demonstrate that ω-3 polyunsaturated fatty acids (PUFAs) inhibit inflammatory eicosanoids generated by ω-6 PUFAs. Epidemiologic studies on dietary ω-3 PUFA intake show consistent inverse associations with breast cancer incidence among Asian populations, where ω-3, relative to ω-6, intake is high. In contrast, associations are inconsistent among Western populations, where intake of ω-3, relative to ω-6, is low. We hypothesized that examining interactions between ω-3 and ω-6 would help elucidate the PUFA-breast cancer association in the United States.

METHODS

In a Long Island, New York, population-based study of 1463 breast cancer cases and 1500 controls, we estimated multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression to examine interactions between ω-3 and ω-6 intake.

RESULTS

We observed a super-additive interaction (relative excess risk due to interaction = 0.41; 95% confidence interval = 0.06-0.76) between ω-3 and ω-6 intake in association with breast cancer incidence, although the CIs for the joint exposure of low ω-3/high ω-6 compared to high ω-3/low ω-6 intake were wide (odds ratio = 1.20; 95% confidence interval = 0.85-1.69).

CONCLUSIONS

Breast cancer risk reduction may be possible for U.S. women with dietary consumption of higher ω-3, which has anti-inflammatory properties, in concert with lower ω-6, which induces inflammation. Replication from future U.S.-based investigations is needed.

Fish, n - 3 polyunsaturated fatty acids and n - 6 polyunsaturated fatty acids intake and breast cancer risk: The Japan Public Health Center-based prospective study

Limited and inconsistent studies exist on the association between the intake of fish, n - 3 polyunsaturated fatty acids (PUFA) and n - 6 PUFA and breast cancer. Fish and n - 3 PUFA support various body functions and are thought to reduce the carcinogenesis risk while n - 6 PUFA may have a positive association with cancer risk. We examined the association between intake of fish, n - 3 PUFA [including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and alpha-linolenic acid (ALA)] and n - 6 PUFA and breast cancer with subanalyses on estrogen (ER) and progesterone receptor (PR) status. We investigated 38,234 Japanese women aged 45-74 years from the Japan Public Health Center-based prospective study (JPHC study), and during 14.1 years of follow-up time, 556 breast cancer cases were newly diagnosed. Breast cancer risk was not associated with the intake of total fish, n - 3 PUFA and n - 6 PUFA when analyzed in totality through multivariable Cox proportional hazards regression models with age as the time scale. Intake of total n - 6 was positively associated with the development of ER+PR+ tumors [multivariable-adjusted HR Q4 vs. Q1  = 2.94 (95% CI: 1.26-6.89; ptrend  = 0.02)]. Intake of EPA was associated with a decreased breast cancer risk for ER+PR+ tumors [multivariable-adjusted HR Q2 vs. Q1  = 0.47 (95% CI: 0.25-0.89; ptrend =0.47)]. While the overall association between the intake of total fish, n - 3 PUFA and n - 6 PUFA and breast cancer risk is null, for ER+PR+ tumors, a positive association was seen between n - 6 intake and breast cancer, and a marginally significant inverse association was observed for EPA intake.

α-Linolenic Acid Reduces Growth of Both Triple Negative and Luminal Breast Cancer Cells in High and Low Estrogen Environments

Flaxseed, rich in α-linolenic acid (ALA), is a complementary breast cancer (BC) therapy; however ALA effectiveness and mechanism are unclear. Variation in cellular expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and estrogen (E2) levels may alter ALA effectiveness. This research determined the effect of ALA on growth, apoptosis, and phospholipid fatty acids of 4 BC cell lines with varying receptor expression ± E2. MCF-7 (ER+/PR+/HER2-), BT-474 (ER+/PR+/HER2+), MDA-MB-231 (ER-/PR-/HER2-) and MDA-MB-468 (ER-/PR-/HER2-) cells were incubated with ALA (50-200 μM) ± 1 nM E2 for 48-72 h. ALA dose-dependently reduced growth, measured by trypan blue exclusion, of all cells (55-80% with 75 μM), and this effect was not altered by E2. ALA (75 μM)+E2 induced apoptosis, measured by flow cytometry (up to 111.2%). Decreased growth and increased apoptosis is related to increased cell phospholipid % ALA (up to 25.1%), measured by gas chromatography. ALA is shown for the first time to reduce cell growth and induce apoptosis regardless of receptor expression and E2 environment, by incorporating into BC phospholipids, supporting the use of ALA and ALA-rich foods as a safe, inexpensive complementary therapy for a wide range of BC.

Omega-3 fatty acids for breast cancer prevention and survivorship

Women with evidence of high intake ratios of the marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) relative to the omega-6 arachidonic acid have been found to have a reduced risk of breast cancer compared with those with low ratios in some but not all case–control and cohort studies. If increasing EPA and DHA relative to arachidonic acid is effective in reducing breast cancer risk, likely mechanisms include reduction in proinflammatory lipid derivatives, inhibition of nuclear factor-κB-induced cytokine production, and decreased growth factor receptor signaling as a result of alteration in membrane lipid rafts. Primary prevention trials with either risk biomarkers or cancer incidence as endpoints are underway but final results of these trials are currently unavailable. EPA and DHA supplementation is also being explored in an effort to help prevent or alleviate common problems after a breast cancer diagnosis, including cardiac and cognitive dysfunction and chemotherapy-induced peripheral neuropathy. The insulin-sensitizing and anabolic properties of EPA and DHA also suggest supplementation studies to determine whether these omega-3 fatty acids might reduce chemotherapy-associated loss of muscle mass and weight gain. We will briefly review relevant omega-3 fatty acid metabolism, and early investigations in breast cancer prevention and survivorship.

Omega-3 fatty acids for breast cancer prevention and survivorship

Women with evidence of high intake ratios of the marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) relative to the omega-6 arachidonic acid have been found to have a reduced risk of breast cancer compared with those with low ratios in some but not all case-control and cohort studies. If increasing EPA and DHA relative to arachidonic acid is effective in reducing breast cancer risk, likely mechanisms include reduction in proinflammatory lipid derivatives, inhibition of nuclear factor-κB-induced cytokine production, and decreased growth factor receptor signaling as a result of alteration in membrane lipid rafts. Primary prevention trials with either risk biomarkers or cancer incidence as endpoints are underway but final results of these trials are currently unavailable. EPA and DHA supplementation is also being explored in an effort to help prevent or alleviate common problems after a breast cancer diagnosis, including cardiac and cognitive dysfunction and chemotherapy-induced peripheral neuropathy. The insulin-sensitizing and anabolic properties of EPA and DHA also suggest supplementation studies to determine whether these omega-3 fatty acids might reduce chemotherapy-associated loss of muscle mass and weight gain. We will briefly review relevant omega-3 fatty acid metabolism, and early investigations in breast cancer prevention and survivorship.

The role of n-3 polyunsaturated fatty acids in the prevention and treatment of breast cancer

Breast cancer (BC) is the most common cancer among women worldwide. Dietary fatty acids, especially n-3 polyunsaturated fatty acids (PUFA), are believed to play a role in reducing BC risk. Evidence has shown that fish consumption or intake of long-chain n-3 PUFA, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are beneficial for inhibiting mammary carcinogenesis. The evidence regarding α-linolenic acid (ALA), however, remains equivocal. It is essential to clarify the relation between ALA and cancer since ALA is the principal source of n-3 PUFA in the Western diet and the conversion of ALA to EPA and DHA is not efficient in humans. In addition, the specific anticancer roles of individual n-3 PUFA, alone, have not yet been identified. Therefore, the present review evaluates ALA, EPA and DHA consumed individually as well as in n-3 PUFA mixtures. Also, their role in the prevention of BC and potential anticancer mechanisms of action are examined. Overall, this review suggests that each n-3 PUFA has promising anticancer effects and warrants further research.

Dietary intakes of fat and total mortality among Japanese populations with a low fat intake: the Japan Collaborative Cohort (JACC) Study

BACKGROUND

It may be useful to examine associations of fat intakes with total mortality as a basis for dietary recommendations. We aimed to elucidate associations between dietary fat and total mortality among Japanese populations with low fat intake.

METHODS

We conducted a prospective study consisting of 58,672 men and women aged 40 to 79 years. Fat intakes were estimated using a food frequency questionnaire. Multivariate-adjusted hazard ratios (HRs) for mortality by sex were computed according to quintiles of energy-adjusted fat intakes.

RESULTS

During the follow-up period (median duration, 19.3 years), 11,656 deaths were recorded. In men, we found no clear association between total fat and total mortality. HRs across quintiles of total fat intake were 1.00, 1.03 (95% confidence interval [CI], 0.95-1.12), 1.02 (0.94-1.10), 0.98 (0.90-1.07), and 1.07 (0.98-1.17). No significant association was detected in regard to types of fat. In women, HR was lowest in the fourth quintile of total fat intake followed by the top quintile; HRs across quintiles were 1.00, 1.03 (0.94-1.11), 1.00 (0.92-1.09), 0.88 (0.81-0.96), and 0.94 (0.86-1.03). Regarding types of fat in women, total mortality was inversely associated with intakes of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA); the lowest HR was in the top quintile of intake for SFA, MUFA, and PUFA: 0.91 (95% CI, 0.83-1.00), 0.91 (0.83-0.99) and 0.88 (0.80 - 0.97), respectively (trend P across quintiles, 0.020, 0.012, and 0.029, respectively). Causes of death other than cancer and cardiovascular disease contributed most to decreases in HRs for total and types of fat. In women, analysis with finer categories revealed that the lowest risk for total mortality appeared at total fat intake of 28% of energy.

CONCLUSIONS

Our findings from a large cohort study among populations with relatively low fat intake provide evidence regarding optimal levels of fat intakes.

Ratio of n-3/n-6 PUFAs and risk of breast cancer: a meta-analysis of 274135 adult females from 11 independent prospective studies

Background

Increased ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs) in diet or serum may have a protective effect on the risk of breast cancer (BC); however, the conclusions from prospective studies are still controversial. The purpose of this study is to ascertain the relationship between intake ratio of n-3/n-6 PUFAs and the risk of BC, and estimate the potential summarized dose–response trend.

Methods

Relevant English-language studies were identified through Cochrane Library, PubMed and EMBASE database till April 2013. Eligible prospective studies reporting the multivariate adjusted risk ratios (RRs) for association of n-3/n-6 PUFAs ratio in diet or serum with BC risk. Data extraction was conducted independently by 2 investigators; disagreements were reconciled by consensus. Study quality was assessed using the Newcastle-Ottawa scale. Study-specific RRs were combined via a random-effects model.

Results

Six prospective nested case–control and 5 cohort studies, involving 8,331 BC events from 274,135 adult females across different countries, were included in present study. Subjects with higher dietary intake ratio of n-3/n-6 PUFAs have a significantly lower risk of BC among study populations (pooled RR = 0.90; 95% CI: 0.82, 0.99), and per 1/10 increment of ratio in diet was associated with a 6% reduction of BC risk (pooled RR = 0.94; 95% CI: 0.90, 0.99; P for linear trend = 0.012). USA subjects with higher ratio of n-3/n-6 in serum phospholipids (PL) have a significantly lower risk of BC (pooled RR = 0.62; 95% CI: 0.39, 0.97; I² = 0.00%; P for metaregression = 0.103; P for a permutation test = 0.100), and per 1/10 increment of ratio in serum PL was associated with 27% reduction of BC risk (pooled RR = 0.73; 95% CI: 0.59, 0.91; P for linear trend = 0.004; P for metaregression = 0.082; P for a permutation test = 0.116).

Conclusions

Higher intake ratio of n-3/n-6 PUFAs is associated with lower risk of BC among females, which implies an important evidence for BC prevention and treatment is by increasing dietary intake ratio of n-3/n-6 PUFA. No firm conclusions from USA populations could be obtained, due to the limited numbers of USA studies.

Relations of omega-3 and omega-6 intake with mammographic breast density

PURPOSE

Omega-3 (n-3) and n-6 fatty acids (FA) intake could influence the occurrence of certain diseases such as breast cancer but little is known about their relation to mammographic density (MD). The purpose of this study is to examine the association of the intake of n-3 FA and n-6 FA with MD among 777 premenopausal and 783 postmenopausal women.

METHODS

In this cross-sectional study, FA intake was assessed with a self-administered food-frequency questionnaire and MD was measured using a computer-assisted method. Multivariate analyses were performed by using generalized linear models to evaluate the associations of quartiles of FA intake with MD.

RESULTS

For increasing quartiles of total long-chain n-3 FA intake (< 0.11, 0.11-0.20, 0.21-0.32, and ≥ 0.33 g/day), adjusted mean MD was 29, 29, 27, and 25 %, respectively (P trend = 0.005). This association remained significant among postmenopausal (P trend = 0.006) but not among premenopausal (P trend = 0.21) women. No significant association was found between n-6 FA intake and MD. However, for increasing quartiles of the n-6 FA/long-chain n-3 FA ratio intake (< 31.75, 31.75-52.28, 52.29-94.28, and ≥ 94.29), adjusted mean MD was 26, 27, 29, and 29 %, respectively (P trend = 0.008).

CONCLUSIONS

Higher intake of long-chain n-3 FA was associated with lower MD, suggesting that increased long-chain n-3 FA intake could be a strategy for breast cancer prevention.

Erythrocyte omega-6 and omega-3 fatty acids and mammographic breast density

Diets low in omega-6 (n-6) polyunsaturated fatty acids (PUFAs) and high in omega-3 (n-3) PUFAs may protect against breast cancer development. Associations of PUFA intake with mammographic density, an intermediate marker of breast cancer risk, have been inconsistent; however, prior studies have relied on self-reported dietary PUFA intake. We examined the association between circulating erythrocyte n-6 and n-3 PUFAs with mammographic density in 248 postmenopausal women who were not taking exogenous hormones. PUFAs in erythrocytes were measured by gas-liquid chromatography, and mammographic density was assessed quantitatively by planimetry. Spearman's correlation coefficients and generalized linear models were used to evaluate the relationships between PUFA measures and mammographic density. None of the erythrocyte n-6 or n-3 PUFA measures were associated with percent density or dense breast area.

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

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

ω-3 and ω-6 Polyunsaturated fatty acid intakes and the risk of breast cancer in Mexican women: impact of obesity status

BACKGROUND

ω-3 polyunsaturated fatty acids (PUFA) could play a protective role on the risk of breast cancer; however, little is known about this relation among Mexican women. We evaluated the association between ω-3 and ω-6 PUFA intake and breast cancer risk by obesity status in Mexican women.

METHODS

A population-based case-control study was conducted in Mexico, including 1,000 incident breast cancer cases and 1,074 controls matched to cases by age, health care system, and region. Women provided information on health and diet by in-person interview. Body mass index (BMI) measures were used to define overall obesity. Obesity status was categorized as normal weight (18.5 < BMI < 25), overweight (25 ≤ BMI < 30), and obese (BMI ≥ 30). A conditional logistic regression model was used to assess the association between PUFA and breast cancer risk.

RESULTS

Overall, there was no significant association between ω-3 PUFA intake and breast cancer risk (P = 0.31). An increased risk of breast cancer was associated with increasing ω-6 PUFA intake in premenopausal women [OR = 1.92, 95% confidence interval (CI) = 1.13-3.26; P = 0.04]. A decreased risk of breast cancer was significantly associated with increasing ω-3 PUFA intake in obese women (OR = 0.58, 95% CI = 0.39-0.87; P = 0.008) but not in normal weight nor in overweight women (P(heterogeneity) = 0.017).

CONCLUSIONS

Obesity status may affect the association between ω-3 PUFA intake and breast cancer risk. The underlying mechanisms may be related to decreased inflammation and improved adipokin and estrogen levels induced by ω-3 PUFA in adipose tissue in obese women.

IMPACT

Increased intake of ω-3 PUFA should be recommended among Mexican women in particular in obese women.

Dietary fat and breast cancer in postmenopausal women according to ethnicity and hormone receptor status: the Multiethnic Cohort Study

Dietary fat has been widely studied as a risk factor for breast cancer, with little consistency in results. The Multiethnic Cohort Study (MEC) provides an opportunity to assess this relationship for possible heterogeneity across different racial/ethnic groups, as well as by stratification on several other variables associated with risk. Therefore, we investigated the associations between dietary fat, overall and by type, and breast cancer risk among 85,089 postmenopausal women who entered the MEC by completing a comprehensive dietary questionnaire in 1993 to 1996. During a mean follow-up of 12 years, 3,885 incident invasive breast cancer cases were identified. The multivariate HR [95% confidence interval (CI)] for the highest versus lowest quintile of intake was 0.94 (95% CI, 0.85-1.05) for total fat and 0.93 (95% CI, 0.83-1.04) for saturated fat. Other specific types of dietary fat, including individual fatty acids, were not related to risk of postmenopausal breast cancer. We found no heterogeneity in these null findings across the five ethnic groups. Furthermore, we found no evidence that the association between dietary fat and postmenopausal breast cancer risk differed by estrogen/progesterone receptor status, tumor stage, body mass index, hormone replacement therapy use, follow-up period, family history of breast cancer, and smoking status at baseline. In conclusion, this comprehensive prospective analysis in the MEC does not support a role of adult intake of dietary fat in the etiology of postmenopausal breast cancer.

Dietary conjugated linoleic acid and long-chain n-3 fatty acids in mammary and prostate cancer protection: a review

The role of dietary fatty acids on cancer is still controversial. To examine the current literature on the protective role of conjugated linoleic acid (CLA) and marine long-chain fatty acids [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] and the risk of breast and prostate cancer, data from 41 case-control and cohort studies and relevant in vitro and animal experiments were included in this 2000-2010 revision. Epidemiological studies on CLA intake or its tissue concentration related to breast and prostate tumorigenesis are not conclusive; EPA and DHA intake have shown important inverse associations just in some studies. Additional research on the analysed association is required.

Dietary polyunsaturated fatty acids and breast cancer risk in Chinese women: a prospective cohort study

Breast cancer is the most common cancer in women. Controversy exists regarding the role of dietary fat in breast cancer etiology. We investigated the association of dietary polyunsaturated fatty acids (PUFAs) and the ratio of n-6 PUFAs to marine-derived n-3 PUFAs with breast cancer risk in the Shanghai Women's Health Study, a prospective cohort study including 72,571 cancer-free participants at baseline. Dietary fatty acid intake was determined using food frequency questionnaires. We used Cox proportional hazards analysis to estimate the relative risks (RRs) and 95% confidence intervals (CIs) for the association of breast cancer risk with dietary fatty acids consumption. In 583,998 person-years of follow-up, we identified 712 breast cancer cases. We found no association of breast cancer risk to dietary intake of linoleic acid, arachidonic acid, α-linolenic acid or marine-derived n-3 PUFA. We found a statistically significant interaction between n-6 PUFA intake, marine-derived n-3 PUFA intake and breast cancer risk (p = 0.008). Women with lower intake (the lowest tertile) of marine-derived n-3 PUFA and higher intake (the highest tertile) of n-6 PUFA had an increase risk for breast cancer (RR = 2.06; 95% CI = 1.27-3.34) compared to women with higher intake (the highest tertile) of marine-derived n-3 PUFAs and lower intake (the lowest tertile) of n-6 PUFAs after adjusting for potential confounders. The relative amounts of n-6 PUFA to marine-derived n-3 PUFAs may be more important for breast cancer risk than individual dietary amounts of these fatty acids.

Hormonal and metabolic modulation through nutrition: towards a primary prevention of breast cancer

Breast cancer (BC) is a polygenic and multifactorial disease for which estrogens have been recognized as the main risk factor, and for which lifestyle plays a key role. Previous epidemiologic cancer research performed in Uruguayan population delimited its dietary and anthropometric profiles. Recognizing the difficulty for universalizing a nutritional basis for prevention due to different eating patterns among regions and countries, we summarize the existent knowledge linking nutrition, estrogens, metabolism and BC. As an attempt towards primary prevention of BC, we present recommendations mainly based on country-specific research findings and modifiable putative risk and protective factors, proposing to modify the intake of meats and other fatty foods--especially sources of Ω-6 and Ω-3 fatty acids--adding olive oil, selected vegetables, citrus fruits and working towards adequate body fat/muscle proportions. From a medical and ethical viewpoint, it is justified to recommend certain nutritional changes to women, because no adverse side effects are expected to occur.