Dietary Fat and Breast Cancer in Postmenopausal Women According to Ethnicity and Hormone Receptor Status: The Multiethnic Cohort Study
ABSTRACT 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.
SourceAvailable from: Maryam Sadat Farvid[Show abstract] [Hide abstract]
ABSTRACT: We examined the association between fat intake and breast cancer incidence in the Nurses’ Health Study II. We followed 88,804 women aged 26–45 years from 1991 to 2011 and documented incident breast cancers. Dietary fat, assessed by questionnaires in 1991, was examined in relation to total, premenopausal, and postmenopausal breast cancers. Multivariable-adjusted Cox proportional hazards models were used to estimate relative risk (RR) and 95 % confidence intervals (95 % CI). During 20 years of follow-up, 2,830 incident invasive breast cancer cases were diagnosed. Total fat intake was not associated with risk of breast cancer overall. After adjustment for demographic, anthropometric, lifestyle, and dietary factors, a positive association was observed between animal fat intake and breast cancer overall (RR for highest vs lowest quintile, 1.18; 95 % CI 1.04–1.33; P trend = 0.01). A positive association with animal fat intake was also seen among premenopausal women, but not among postmenopausal women. Higher intakes of saturated fat and monounsaturated fat were each associated with modestly higher breast cancer risk among all women, and higher cholesterol intake was associated with higher premenopausal breast cancer risk. However, the associations of saturated fat, monounsaturated fat and animal fat, were attenuated and non-significant after adjustment for red meat intake. Intakes of other types of fat including vegetable fat, dairy fat, polyunsaturated fat, and trans fat were not associated with breast cancer risk. Our finding suggests a positive association between early adult intake of animal fat and breast cancer risk.Breast Cancer Research and Treatment 05/2014; 145(1). DOI:10.1007/s10549-014-2895-9 · 4.20 Impact Factor
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ABSTRACT: We prospectively evaluated fat intake as predictor of developing breast cancer (BC) subtypes defined by estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 receptor (HER2), in a large (n = 337327) heterogeneous cohort of women, with 10062 BC case patients after 11.5 years, estimating BC hazard ratios (HRs) by Cox proportional hazard modeling. High total and saturated fat were associated with greater risk of ER(+)PR(+) disease (HR = 1.20, 95% confidence interval [CI] = 1.00 to 1.45; HR = 1.28, 95% CI = 1.09 to 1.52; highest vs lowest quintiles) but not ER(-)PR(-) disease. High saturated fat was statistically significantly associated with greater risk of HER2(-) disease. High saturated fat intake particularly increases risk of receptor-positive disease, suggesting saturated fat involvement in the etiology of this BC subtype.CancerSpectrum Knowledge Environment 04/2014; DOI:10.1093/jnci/dju068 · 15.16 Impact Factor
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ABSTRACT: The effects of both the amount and quality of dietary fat have been studied intensively during the past decades. Previously, low-fat diets were recommended without much attention to the quality of fat, whereas there is general emphasis on the quality of fat in current guidelines. The objective of this systematic review (SR) was to assess the evidence of an effect of the amount and type of dietary fat on body weight (BW), risk factors, and risk of non-communicable diseases, that is, type 2 diabetes (T2DM), cardiovascular diseases (CVD), and cancer in healthy subjects or subjects at risk for these diseases. This work was performed in the process of updating the fourth edition of the Nordic Nutrition Recommendations from 2004. The literature search was performed in October 2010 covering articles published since January 2000. A complementary search was done in February 2012 covering literature until December 2011. Two authors independently selected articles for inclusion from a total of about 16,000 abstracts according to predefined criteria. Randomized controlled trials (RCT) and prospective cohort studies (PCS) were included as well as nested case-control studies. A few retrospective case-control studies were also included when limited or no data were available from other study types. Altogether 607 articles were quality graded and the observed effects in these papers were summarized. Convincing evidence was found that partial replacement of saturated fat (SFA) with polyunsaturated fat (PUFA) or monounsaturated fat (MUFA) lowers fasting serum/plasma total and LDL cholesterol concentrations. The evidence was probable for a decreasing effect of fish oil on concentration of serum/plasma total triglycerides as compared with MUFA. Beneficial effect of MUFA both on insulin sensitivity and fasting plasma/serum insulin concentration was considered as probable in comparisons of MUFA and carbohydrates versus SFA, whereas no effect was found on fasting glucose concentration in these comparisons. There was probable evidence for a moderate direct association between total fat intake and BW. Furthermore, there was convincing evidence that partial replacement of SFA with PUFA decreases the risk of CVD, especially in men. This finding was supported by an association with biomarkers of PUFA intake; the evidence of a beneficial effect of dietary total PUFA, n-6 PUFA, and linoleic acid (LA) on CVD mortality was limited suggestive. Evidence for a direct association between total fat intake and risk of T2DM was inconclusive, whereas there was limited-suggestive evidence from biomarker studies that LA is inversely associated with the risk of T2DM. However, there was limited-suggestive evidence in biomarker studies that odd-chain SFA found in milk fat and fish may be inversely related to T2DM, but these associations have not been supported by controlled studies. The evidence for an association between dietary n-3 PUFA and T2DM was inconclusive. Evidence for effects of fat on major types of cancer was inconclusive regarding both the amount and quality of dietary fat, except for prostate cancer where there was limited-suggestive evidence for an inverse association with intake of ALA and for ovarian cancer for which there was limited-suggestive evidence for a positive association with intake of SFA. This SR reviewed a large number of studies focusing on several different health outcomes. The time period covered by the search may not have allowed obtaining the full picture of the evidence in all areas covered by this SR. However, several SRs and meta-analyses that covered studies published before year 2000 were evaluated, which adds confidence to the results. Many of the investigated questions remain unresolved, mainly because of few studies on certain outcomes, conflicting results from studies, and lack of high quality-controlled studies. There is thus an evident need of highly controlled RCT and PCS with sufficient number of subjects and long enough duration, specifically regarding the effects of the amount and quality of dietary fat on insulin sensitivity, T2DM, low-grade inflammation, and blood pressure. New metabolic and other potential risk markers and utilization of new methodology in the area of lipid metabolism may provide new insight.Food & Nutrition Research 07/2014; 58. DOI:10.3402/fnr.v58.25145 · 1.79 Impact Factor