Folate, vitamin B(6), and vitamin B(12) intake and the risk of breast cancer among Mexican women.

BACKGROUND: High intake of folate, vitamin B(6), and vitamin B(12) have been hypothesized to lower the risk for breast cancer. We conducted a population-based case-control study to evaluate the risk for breast cancer among Mexican women with relatively low vitamin intakes. METHODS: We included 475 women (median age, 53 years; range, 23-87 years) diagnosed with incident breast cancer through six hospitals in Mexico City and interviewed them to obtain data on breast cancer risk factors and their usual diet using a food frequency questionnaire. We selected 1,391 (median age, 49 years; range, 18-82 years) controls from the Mexico City population using a national sampling frame. RESULTS: Compared with women in the lowest quartile, the odds ratio for breast cancer for women in the highest quartile of folate intake was 0.64 [95% confidence intervals (CI), 0.45-0.90; P, test for trend = 0.009] and 0.32 (95% CI, 0.22-0.49; P, test for trend < 0.0001) for vitamin B(12) intake. Among postmenopausal women, intakes of folate and vitamin B(12) were associated with a lower risk of breast cancer and those associations were stronger than among premenopausal women. The inverse association of folate and breast cancer was stronger among women who consumed a high level of vitamin B(12) as compared with women consuming diets low in vitamin B(12). No association was observed for vitamin B(6) intake. CONCLUSIONS: In this population, high intakes of folate and vitamin B(12) were independently associated with decreased breast cancer risk, particularly among postmenopausal women.     

Opposing effects of dietary n-3 and n-6 fatty acids on mammary carcinogenesis: The Singapore Chinese Health Study

We investigated the effects of individual fatty acids on breast cancer in a prospective study of 35,298 Singapore Chinese women aged 45-74 years, who were enrolled during April 1993 to December 1998 (The Singapore Chinese Health Study). At recruitment, each study subject was administered, in-person, a validated, semiquantitative food frequency questionnaire consisting of 165 food and beverage items. As of December 31, 2000, 314 incident cases of breast cancer had occurred. We used the Cox regression methods to examine individual fatty acids in relation to breast cancer risk, with adjustment for age at baseline interview, year of interview, dialect group, level of education, daily alcohol drinking, number of live births, age when menstrual periods became regular, and family history of breast cancer. Consumption of saturated, monounsaturated or polyunsaturated fat overall was unrelated to risk. On the other hand, high levels of dietary n-3 fatty acids from fish/shellfish (marine n-3 fatty acids) were significantly associated with reduced risk. Relative to the lowest quartile of intake, individuals in the higher three quartiles exhibited a 26% reduction in risk (relative risk (RR)=0.74, 95% confidence interval (CI)=0.58, 0.94)); RRs were similar across the top three quartiles of intake (0.75, 0.75, 0.72, respectively). Overall, there was no association between n-6 fatty acids and breast cancer risk. However, among subjects who consumed low levels of marine n-3 fatty acids (lowest quartile of intake), a statistically significant increase in risk was observed in individuals belonging to the highest vs the lowest quartile of n-6 fatty acid consumption (RR=1.87, 95% CI=1.06-3.27); the corresponding RR for advanced breast cancer was 2.45 (95% CI=1.20-4.97, P for trend=0.01). To our knowledge, these are the first prospective findings linking the intake of marine n-3 fatty acids to breast cancer protection.     

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

To examine the possible association of dietary fat and fatty acids with breast cancer risk in a population with a low total fat intake and a high consumption of fish, we analyzed data from the Japan Collaborative Cohort (JACC) Study. From 1988 to 1990, 26 291 women aged 40-79 years completed a questionnaire on dietary and other factors. Intakes of fat or fatty acids were estimated by using a food frequency questionnaire. Rate ratios (RR) were computed by fitting proportional hazards models. During the mean follow-up of 7.6 years, 129 breast cancer cases were documented. We found no clear association of total fat intake with breast cancer risk; the multivariate-adjusted RR across quartiles were 1.00, 1.29, 0.95, and 0.80 (95% confidence interval [CI] 0.46-1.38). A significant decrease in the risk was detected for the highest quartile of intake compared with the lowest for fish fat and long-chain n-3 fatty acids; the RR were 0.56 (95% CI 0.33-0.94) and 0.50 (0.30-0.85), respectively. A decreasing trend in risk was also suggested with an increasing intake of saturated fatty acids (trend P = 0.066). Among postmenopausal women at baseline, the highest quartile of vegetable fat intake was associated with a 2.08-fold increase in risk (95% CI 1.05-4.13). This prospective study did not support any increase in the risk of breast cancer associated with total or saturated fat intake, but it suggested the protective effects of the long-chain n-3 fatty acids that are abundant in fish.     

Carbohydrates and the risk of breast cancer among Mexican women.

OBJECTIVE: High carbohydrate intake has been hypothesized to be a risk factor for breast cancer, possibly mediated by elevated levels of free insulin, estrogens, and insulin-like growth factor-1. Therefore, we conducted a population-based case-control study among a Mexican population characterized by relatively low fat and high carbohydrate intakes. METHODS: Women ages 20 to 75 years, identified through six hospitals in Mexico City (n = 475), were interviewed to obtain data relating to diet (using a food frequency questionnaire) and breast cancer risk factors. Controls (n = 1,391) were selected from the Mexico City population using a national sampling frame. RESULTS: Carbohydrate intake was positively associated with breast cancer risk. Compared with women in the lowest quartile of total carbohydrate intake, the relative risk of breast cancer for women in the highest quartile was 2.22 [95% confidence interval (95% CI) 1.63-3.04], adjusting for total energy and potential confounding variables (P for trend < 0.0001). This association was present in premenopausal and postmenopausal women (for highest versus lowest quartile, odds ratio 2.31, 95% CI 1.36-3.91 in premenopausal women and odds ratio 2.22, 95% CI 1.49-3.30 in postmenopausal women). Among carbohydrate components, the strongest associations were observed for sucrose and fructose. No association was observed with total fat intake. DISCUSSION: In this population, a high percentage of calories from carbohydrate, but not from fat, was associated with increased breast cancer risk. This relation deserves to be investigated further, particularly in populations highly susceptible to insulin resistance.     

Dietary intake of selected fatty acids,cholesterol and carotenoids and estrogen receptor status in premenopausal breast cancer patients

Although a wealth of research has focused on the influence of diet on breast cancer risk, the relationships between dietary factors and tumor characteristics of breast cancer, like estrogen receptor (ER) status, are not well characterized. In a case-case study, we evaluated self-reported dietary intake for five individual carotenoids, selected fatty acids, and cholesterol 1 year before diagnosis in 34 premenopausal breast cancer patients with ER-negative tumors and 86 premenopausal breast cancer patients with ER-positive tumors from The University of Texas M. D. Anderson Cancer Center. In multivariate logistic regression analysis adjusted for age, body mass index, and ethnicity, high intakes of linoleic acid were associated with more than a threefold greater risk of ER-negative disease than ER-positive disease (odds ratio (OR) = 3.48, 95% confidence interval (CI) = 1.42–8.54), whereas high cholesterol intake was associated with lower risk of ER-negative disease (OR = 0.35, 95% CI = 0.14–0.92). In a model evaluating carotenoids, selected fatty acids, and cholesterol together, the association with high intake of linoleic acid remained statistically significant (OR = 3.96, 95% CI = 1.53–10.25), while those for high intake of cholesterol (OR = 0.38, 95% CI = 0.14–1.03) and low intake of cryptoxanthin (OR = 0.43, 95% CI = 0.17–1.06) were of marginal significance. While no striking associations were observed for the intakes of total carotenoids, selected fatty acids, and cholesterol, our analysis revealed an association for the consumption of a specific fatty acid (i.e., linoleic acid), suggesting dietary influence of this factor on ER status in premenopausal breast cancer patients. However, larger studies are needed to clarify the role of micronutrients in ER status in breast cancer.     

Dietary lignan intakes and risk of pre- and postmenopausal breast cancer

Lignans are plant compounds metabolized in the mammalian gut to produce the phytoestrogens enterolactone and enterodiol. Because estrogens have been linked to breast cancer etiology, lignans could affect breast cancer risk through modulation of endogenous estrogen metabolism or competitive inhibition with estrogen receptors. We examined breast cancer risk and dietary lignan intake in a population-based case-control study of 1,122 women with primary, incident, histologically confirmed breast cancer and 2,036 controls frequency matched to cases on age and county of residence as part of the Western New York Exposures and Breast Cancer (WEB) Study. Diet was assessed with a self-administered 104-item food frequency questionnaire and other relevant data were collected by detailed in-person interviews. Lignans were expressed as the sum of the dietary precursors secoisolariciresinol and matairesinol. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional logistic regression, adjusting for age, total energy and other breast cancer risk factors. Premenopausal women in the highest quartile of dietary lignan intake had reduced breast cancer risk (OR = 0.66; 95% CI = 0.44-0.98). No association was observed between lignan intakes and postmenopausal breast cancer. Our results suggest that dietary lignans may be important in the etiology of breast cancer, particularly among premenopausal women.     

Premenopausal dietary fat in relation to pre- and post-menopausal breast cancer

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.     

Plasma enterolactone and genistein and the risk of premenopausal breast cancer.

BACKGROUND: The scientific debate on the role of dietary phytoestrogens for prevention of breast cancer is still ongoing. We previously reported an inverse association between dietary phytoestrogen intake and premenopausal breast cancer risk and now examine the relationship with plasma phytoestrogen concentrations. METHODS: We measured enterolactone (mammalian lignan) and genistein (isoflavone) concentrations in plasma samples of 220 premenopausal cases and 237 age-matched controls from a population-based case-control study in Germany. RESULTS: Median plasma enterolactone concentrations in cases and controls were 6.3 and 9.7 nmol/l, respectively, and median genistein concentrations were 4.5 and 3.7 nmol/l, respectively. Premenopausal breast cancer risk decreased with increasing plasma enterolactone concentrations. Adjusted odds ratios (95% confidence intervals) were 0.42 (0.20-0.90) and 0.38 (0.17-0.85) (P for trend 0.007) for women in the third and fourth quartile of plasma enterolactone compared to those in the lowest quartile. There was no significant association between plasma genistein concentration and premenopausal breast cancer risk. CONCLUSION: Using biomarkers of phytoestrogen intake, we confirmed the strong inverse association between enterolactone and premenopausal breast cancer risk as found with dietary intake estimates. This result gives support to the potential role of mammalian lignans for breast cancer prevention among premenopausal women in Western populations.     

Total energy intake and breast cancer risk in sisters: the Breast Cancer Family Registry

Energy restriction inhibits mammary tumor development in animal models. Epidemiologic studies in humans generally do not support an association between dietary energy intake and breast cancer risk, although some studies suggest a more complex interplay between measures of energy intake, physical activity, and body size. We examined the association between total energy intake jointly with physical activity and body mass index (BMI) and the risk of breast cancer among 1,775 women diagnosed with breast cancer between 1995 and 2006 and 2,529 of their unaffected sisters, enrolled in the Breast Cancer Family Registry. We collected dietary data using the Hawaii–Los Angeles Multiethnic Cohort food frequency questionnaire. Using conditional logistic regression to estimate the odds ratios (OR) and 95 % confidence intervals (CI) associated with total energy intake, we observed an overall 60–70 % increased risk of breast cancer among women in the highest quartile of total energy intake compared to those in the lowest quartile (Q4 vs. Q1: OR = 1.6, 95 % CI: 1.3–2.0; P _trend < 0.0001); these associations were limited to pre-menopausal women or women with hormone receptor-positive cancers. Although the associations were slightly stronger among women with a higher BMI or lower level of average lifetime physical activity, we observed a positive association between total energy intake and breast cancer risk across different strata of physical activity and BMI. Our results suggest that within sisters, high energy intake may increase the risk of breast cancer independent of physical activity and body size. If replicated in prospective studies, then these findings suggest that reductions in total energy intake may help in modifying breast cancer risk.     

Fatty-acid composition in serum phospholipids and risk of breast cancer: an incident case-control study in Sweden.

The study of the relationship between dietary intake of fatty acids and the risk of breast cancer has not yielded definite conclusions with respect to causality, possibly because of methodological issues inherent to nutritional epidemiology. To evaluate the hypothesis of possible protection of n-3 polyunsaturated fatty acids (PUFA) against breast cancer in women, we examined the fatty-acid composition of phospholipids in pre-diagnostic sera of 196 women who developed breast cancer, and of 388 controls matched for age at recruitment and duration of follow-up, in a prospective cohort study in Umea, northern Sweden. Individual fatty acids were measured as a percentage of total fatty acids, using capillary gas chromatography. Conditional logistic-regression models showed no significant association between n-3 PUFA and breast-cancer risk. In contrast, women in the highest quartile of stearic acid had a relative risk of 0.49 (95% confidence interval, 0.22-1.08) compared with women in the lowest quartile (trend p = 0.047), suggesting a protective role of stearic acid in breast-cancer risk. Besides stearic acid, women in the highest quartile of the 18:0/18:1 n-9c ratio had a relative risk of 0.50 (95% confidence interval, 0.23-1.10) compared with women in the lowest quartile (trend p = 0.064), suggesting a decrease in breast-cancer risk in women with low activity of the enzyme delta 9-desaturase (stearoyl CoA desaturase), which may reflect an underlying metabolic profile characterized by insulin resistance and chronic hyper-insulinemia.     

A 22-year Prospective Study of Fish, n-3 Fatty Acid Intake, and Colorectal Cancer Risk in Men.

BACKGROUND: Fish is the main dietary source of long-chain n-3 fatty acids, which have been suggested to play a protective role in colorectal cancer development in laboratory and animal studies. Human studies have not shown consistent results. We examined the association between intakes of fish and n-3 fatty acids from fish and colorectal cancer risk in men enrolled in the Physicians' Health Study. METHODS: The Physicians' Health Study began as a randomized trial to examine the effect of aspirin and beta-carotene supplementation on cancer and cardiovascular disease. Fish intake was assessed at the 12-month follow-up with an abbreviated food-frequency questionnaire. Cox proportional hazards models were used to estimate multivariate relative risks for colorectal cancer for the categories of fish intake and quartiles of n-3 fatty acid intake. RESULTS: During 22 years of follow-up, 500 men had a confirmed diagnosis of colorectal cancer. Fish intake was inversely associated with colorectal cancer risk [multivariate relative risk (95% confidence interval) for highest versus lowest category, 0.60 (0.40-0.91); P trend = 0.01]. The inverse association was observed for both colon and rectal cancers. Our findings for n-3 fatty acids were similar to those for fish; the multivariate relative risk (95% confidence interval) of total colorectal cancer for the highest versus lowest quartile of n-3 fatty acids was 0.74 (0.57-0.95; P trend = 0.01). CONCLUSIONS: Our results from this long-term prospective study suggest that intakes of fish and long-chain n-3 fatty acids from fish may decrease the risk for colorectal cancer.     

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.     

Associations of dietary folate,Vitamins B6 and B12 and methionine intake with risk of breast cancer among African American and European American women

African American (AA) women are more likely than European American (EA) women to be diagnosed with breast cancer at younger ages and to develop poor prognosis tumors. However, these racial differences are largely unexplained. Folate and other methyl‐group nutrients may be related to breast carcinogenesis, but few studies have examined these associations in AA populations. We examined the associations of dietary intake of these nutrients with breast cancer risk overall, by menopausal and estrogen receptor (ER) status among 1,582 AA (749 cases) and 1,434 EA (744 cases) women using data from a case–control study, the Women's Circle of Health Study. Unconditional multivariable logistic regression models were used to compute odds ratios (ORs) and 95% confidence intervals (CIs) for the association of each nutrient and breast cancer risk. In AA women, inverse associations were observed for natural food folate intake among premenopausal women (fourth vs. first quartile: OR = 0.57, 95% CI, 0.33–1.00; p for trend = 0.06) and for ER‐positive tumors (fourth vs. first quartile: OR = 0.58, 95% CI, 0.36–0.93; p for trend = 0.03), whereas in EA women, a positive association was observed for intake of synthetic folate (fourth vs. first quartile: OR = 1.53, 95% CI, 1.06–2.21; p for trend = 0.03). Our findings suggest that natural food folate intake is inversely associated with breast cancer risk and that this association may vary by race, menopausal status or ER status. The finding of an increased risk observed among EA women with the highest intake of synthetic folate from fortified foods warrants further investigation.     

Dietary carotenoids and vitamins A, C, and E and risk of breast cancer

BACKGROUND: Data on intake of specific carotenoids and breast cancer risk are limited. Furthermore, studies of vitamins A, C, and E in relation to breast cancer risk are inconclusive. We have conducted a large, prospective study to evaluate long-term intakes of these nutrients and breast cancer risk. METHODS: We examined, by use of multivariate analysis, associations between intakes of specific carotenoids, vitamins A, C, and E , consumption of fruits and vegetables, and breast cancer risk in a cohort of 83234 women (aged 33-60 years in 1980) who were participating in the Nurses' Health Study. Through 1994, we identified 2697 incident cases of invasive breast cancer (784 premenopausal and 1913 postmenopausal). RESULTS: Intakes of beta-carotene from food and supplements, lutein/zeaxanthin, and vitamin A from foods were weakly inversely associated with breast cancer risk in premenopausal women. Strong inverse associations were found for increasing quintiles of alpha-carotene, beta-carotene, lutein/zeaxanthin, total vitamin C from foods, and total vitamin A among premenopausal women with a positive family history of breast cancer. An inverse association was also found for increasing quintiles of beta-carotene among premenopausal women who consumed 15 g or more of alcohol per day. Premenopausal women who consumed five or more servings per day of fruits and vegetables had modestly lower risk of breast cancer than those who had less than two servings per day (relative risk [RR] = 0.77; 95% confidence interval [CI] = 0.58-1.02); this association was stronger among premenopausal women who had a positive family history of breast cancer (RR = 0.29; 95% CI = 0.13-0.62) or those who consumed 15 g or more of alcohol per day (RR = 0.53; 95% CI = 0.27-1.04). CONCLUSIONS: Consumption of fruits and vegetables high in specific carotenoids and vitamins may reduce premenopausal breast cancer risk.     

Dietary flavonols and flavonol-rich foods intake and the risk of breast cancer

Laboratory and animal studies suggest that dietary flavonols may reduce breast cancer risk but there are limited epidemiological studies. We computed flavonol intakes from dietary data collected by validated food frequency questionnaires in 1991 and 1995 from 90,630 women in the Nurses Health Study II. Using multivariate relative risks (RR) and 95% confidence intervals (95% CI), we evaluated the association of flavonol intake with breast cancer risk in women who were premenopausal and aged between 26 and 46 years at baseline in 1991. During 8 years of follow-up, we documented 710 cases of invasive breast cancer. The multivariate RR (95% CI), comparing highest to lowest quintiles of cumulative average intake, was 1.05 (0.83, 1.34; p-value for test of trend=0.96) for the sum of flavonols and there were no associations seen between individual flavonols such as kaempferol, quercetin and myricetin and breast cancer risk. The multivariate RR (95% CI), comparing highest to lowest quintiles of cumulative average intake, was 0.94 (0.72, 1.22; p-value for test of trend=0.54) for sum of flavonol-rich foods. Among the major food sources of flavonols, we found a significant inverse association with intake of beans or lentils but not with tea, onions, apples, string beans, broccoli, green pepper and blueberries. The multivariate RR (95% CI), comparing the highest category (2 or more times a week) of cumulative average beans or lentils intake with the lowest category (less than once a month), was 0.76 (0.57, 1.00; p-value for test of trend=0.03). While we found no overall association between intake of flavonols and risk of breast cancer, there was an inverse association with intake of beans or lentils that merits further evaluation.     

Vitamin D and calcium intakes from food or supplements and mammographic breast density.

BACKGROUND: A better understanding of factors that affect breast density, one of the strongest breast cancer risk indicators, may provide important clues about breast cancer etiology and prevention. This study evaluates the association of vitamin D and calcium, from food and/or supplements, to breast density in premenopausal and postmenopausal women separately. METHODS: A total of 777 premenopausal and 783 post-menopausal women recruited at two radiology clinics in Quebec City, Canada, in 2001 to 2002, completed a food frequency questionnaire to assess vitamin D and calcium. Breast density from screening mammograms was assessed using a computer-assisted method. Associations between vitamin D or calcium and breast density were evaluated using linear regression models. Adjusted means in breast density were assessed according to the combined daily intakes of the two nutrients using generalized linear models. RESULTS: In premenopausal women, total intakes of vitamin D and calcium were inversely related to breast density (beta = -1.4; P = 0.004 for vitamin D; beta = -0.8; P = 0.0004 for calcium). In multivariate linear regression, simultaneous increments in daily total intakes of 400 IU vitamin D and 1,000 mg calcium were associated with an 8.5% (95% confidence interval, 1.8-15.1) lower mean breast density. The negative association between dietary vitamin D intake and breast density tended to be stronger at higher levels of calcium intake and vice versa. Among postmenopausal women, intakes of vitamin D and calcium were not associated with breast density. CONCLUSION: These findings show that higher intakes of vitamin D and calcium from food and supplements are related to lower levels of breast density among premenopausal women. They suggest that increasing intakes of vitamin D and calcium may represent a safe and inexpensive strategy for breast cancer prevention.     

Fruit and vegetable intake and breast cancer risk defined by estrogen and progesterone receptor status: the Japan Public Health Center-based Prospective Study

Background

Epidemiological evidence for the impact of fruit and vegetable intake on breast cancer risk among the Japanese populations is scarce.

Objective

The purpose of this study was to evaluate the association between fruit and vegetable intake and breast cancer risk among 47,289 Japanese women.

Design

The study was conducted under a population-based prospective cohort design. Dietary assessment was performed using a validated food frequency questionnaire. A Cox proportional hazards regression model was used to calculate relative risks (RRs) and their corresponding 95 % confidence intervals (CIs).

Results

During an average of 10.2 years of follow-up, 452 cases of breast cancer were newly diagnosed. No association with breast cancer risk was seen for intake of total fruits and vegetables, cruciferous vegetables, green-leaf vegetables, yellow vegetables, or tomato products in overall or postmenopausal women. Cruciferous vegetable intake was associated with a statistically significant decrease in risk of premenopausal breast cancer [multivariable-RR_{Q4 vs. Q1} = 0.64 (95 % CI = 0.38–1.10; p _trend = .046)] and showed a marginally inverse association with ER+ PR+ tumors [RR_{per 100 g increment} = 0.64 (95 % CI = 0.41–1.00)]. In contrast, positive associations were seen between intake of total fruits and citrus fruits and breast cancer risk in overall and premenopausal women. However, these associations for fruit were all attenuated with additional adjustment for vitamin C intake.

Conclusions

Our results suggest an overall null association between total fruit and vegetable intake and breast cancer risk. Intake of cruciferous vegetable showed a statistically significant association with a decreased risk of breast cancer among premenopausal women.     

Dietary Carbohydrate,Fiber and Sugar and Risk of Breast Cancer According to Menopausal Status in Malaysia

Background: Dietary carbohydrate, fiber and sugar intake has been shown to play a role in the etiology ofbreast cancer, but the findings have been inconsistent and limited to developed countries with higher cancerincidence. Objective: To examine the association of premenopausal and postmenopausal breast cancer risk withdietary carbohydrate, fiber and sugar intake. Materials and Methods: This population based case-control studywas conducted in Malaysia with 382 breast cancer patients and 382 controls. Food intake pattern was assessed viaan interviewer-administered food frequency questionnaire. Logistic regression was used to compute odds ratios(OR) with 95% confidence intervals (CI) and a broad range of potential confounders were included in analysis.Results: A significant two fold increased risk of breast cancer among premenopausal (OR Q4 to Q1=1.93, 95%CI:1.53-2.61, p-trend=0.001) and postmenopausal (OR Q4 to Q1=1.87, 95%CI: 1.03-2.61, p-trend=0.045) womenwas observed in the highest quartile of sugar. A higher intake of dietary fiber was associated with a significantlylower breast cancer risk among both premenopausal (ORQ4 to Q1=0.31, 95%CI: 0.12-0.79, p-trend=0.009) andpostmenopausal (ORQ4 to Q1=0.23, 95%CI: 0.07-0.76, p-trend=0.031) women. Conclusions: Sugar and dietaryfiber intake were independently related to pre- and postmenopausal breast cancer risk. However, no associationwas observed for dietary carbohydrate intake.     

Serum fatty acids and risk of breast cancer in a nested case-control study of the New York University Women's Health Study.

Migrant and experimental animal studies suggest that differences in breast cancer incidence rates may be related, in part, to intake of dietary fat. The experimental evidence indicates that total fat, saturated, and n-6 polyunsaturated fatty acids (PUFAs) may stimulate both mammary tumor growth and metastasis, whereas n-3 PUFAs may have a tumor-inhibiting effect. Overall, epidemiological studies do not appear to confirm such observations. Within a cohort of women in the New York University Women's Health Study, the fatty acid composition of serum phospholipids was analyzed by gas chromatography among 197 pre- and postmenopausal clinically identified breast cancer subjects and their matched controls. Individual fatty acids in serum phospholipids were expressed as a percentage of total fatty acids. No significant difference was observed in the proportion of saturated fatty acids (SFAs), monounsaturated fatty acids, or n-6 and n-3 PUFAs between cases and controls. After menopause, total SFAs were positively associated with the risk of breast cancer [odds ratio (OR) = 1.96, 95% confidence interval (CI): 0.73-5.25; P = 0.05] after adjustment for potential confounding factors. Myristc acid (C14:0) was suggestive of a small increase in breast cancer risk in premenopausal women (OR = 2.22, 95% CI: 0.78-6.31), whereas palmitic acid (C16:0) showed similar trends in postmenopausal women (OR = 2.57, 95% CI: 0.99-6.61). Overall, total PUFAs (n-6 and n-3) were suggestive of a small protective effect (OR = 0.59, 95% CI: 0.31-1.09). No significant associations were found between other fatty acids and the risk of breast cancer. The study suggested evidence of an association between serum levels of SFAs and the risk of breast cancer in postmenopausal women. Neither individual n-3 fatty acids of marine origin, eicosapentaenoic acid (C20:5 n-3), and docosahexaenoic acid (C22:6 n-3), nor n-6 PUFAs were related to cancer risk in this study.     

Alcohol consumption‐associated breast cancer incidence and potential effect modifiers: the Japan Public Health Center‐based Prospective Study

Epidemiological studies have evaluated whether the impact of alcohol intake on breast cancer risk is modified by use of exogenous estrogens, folate intake, body weight and smoking status, but results have been inconsistent. Further, effect modification by intake of isoflavones and alcohol‐induced facial flushing, which are prevalent in Asian populations, have not been investigated. We investigated the association between alcohol intake and breast cancer risk and whether the association is modified by these factors among 50,757 premenopausal and postmenopausal women (aged 40–69 years) in the population‐based Japan Public Health Center‐based Prospective Study. Alcohol consumption and other related factors were assessed using self‐reported questionnaires. Through to the end of 2006, 572 patients were identified. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated by hazard ratios derived from Cox proportional hazards regression models. Compared with never‐drinkers, regular alcohol drinkers (>150 g of ethanol/week) had a higher risk of the development of breast cancer; the multivariable‐adjusted RRs were 1.75 (95% CI = 1.16–2.65; p_trend = 0.035) for overall, 1.78 (95% CI = 1.09–2.90) for premenopausal and 1.21 (95% CI = 0.53–2.75) for postmenopausal women. There was no statistical evidence for effect modification by menopausal status, use of exogenous estrogens, intakes of isoflavone and folate, body weight, alcohol‐induced facial flushing or smoking (All p_interactions ≥ 0.15). Excessive alcohol intake was associated with an increase in the risk of breast cancer in this population. There was no statistical evidence for effect modification.