Body size changes in relation to postmenopausal breast cancer among women on Long Island, New York

To examine effects of body size change on postmenopausal breast cancer, the authors conducted a population-based case-control study among 990 cases and 1,006 controls participating in the Long Island Breast Cancer Study Project in 1996-1997. Women who had gained more than 15 kg (33 pounds) since age 20 years were at a 1.6-fold increased risk of breast cancer (95% confidence interval (CI): 1.11, 2.26) relative to their counterparts with stable (+/-3 kg) weight. Subjects who had gained more than 11 kg (24 pounds) during the peri- and postmenopausal years (since age 50 years) had 1.62 times the risk of breast cancer of those whose weight remained unchanged during this time period. This effect of peri- and postmenopausal body size gain was present only among never users of hormone replacement therapy (odds ratio (OR) = 2.02 (95% CI: 1.35, 3.02) as opposed to 0.81 (95% CI: 0.43, 1.53) for ever users; multiplicative interaction: p < 0.01) and was more pronounced among women with estrogen receptor-positive/progesterone receptor-positive breast cancer (OR = 2.17, 95% CI: 1.38, 3.42). Weight loss over the lifetime was associated with decreased risk of postmenopausal breast cancer (OR = 0.55, 95% CI: 0.32, 0.96). These results add to the literature by focusing on the perimenopausal weight trajectory and support efforts urging women to avoid weight gain as they age.     

身体测量指标与女性乳腺癌关系的前瞻性队列研究

目的研究上海女性身体测量指标与绝经前后乳腺癌之间的关系.方法采用前瞻性队列研究方法.1997-2000年在上海市区建立一个73 461人年龄40～70岁的女性队列.每2年随访一次,至2004年6月共收集乳腺癌新发病例432例.用Cox回归模型估计身体测量指标与女性乳腺癌发生的相对危险度（RR）和95%可信区间（CI）.结果调整年龄、文化程度、能量摄入、月经、生育等混杂因素后,基线调查时体重、体重指数（BMI）、腰臀围比例（WHR）和20岁后体重增加与绝经后女性乳腺癌危险性呈正相关,与绝经前女性乳腺癌发生无关.身高与乳腺癌危险的显著正相关关系仅在绝经前女性中发现,20岁时身高在161 cm以上者发生乳腺癌的危险是157.1 cm以下者的1.84倍（95%CI：1.30～2.61）.20岁时BMI处于平均水平者绝经前患乳腺癌的危险性显著高于其他两组.BMI和WHR互相调整后,WHR独立于BMI的作用接近显著性水平.调整BMI后,20岁后体重增加会显著增加绝经后乳腺癌危险（RR=1.61,95%CI：1.09～2.37）.结论对于绝经后女性,成年后体重增加和中心性肥胖都是预测乳腺癌危险的指标.因此控制成年后体重、减少腹部脂肪堆积是预防绝经后乳腺癌发生的有效措施.身高可能是影响绝经前女性乳腺癌发生的危险因素.     

Pooled analysis of prospective cohort studies on height, weight, and breast cancer risk

The association between anthropometric indices and the risk of breast cancer was analyzed using pooled data from seven prospective cohort studies. Together, these cohorts comprise 337,819 women and 4,385 incident invasive breast cancer cases. In multivariate analyses controlling for reproductive, dietary, and other risk factors, the pooled relative risk (RR) of breast cancer per height increment of 5 cm was 1.02 (95% confidence interval (CI): 0.96, 1.10) in premenopausal women and 1.07 (95% CI: 1.03, 1.12) in postmenopausal women. Body mass index (BMI) showed significant inverse and positive associations with breast cancer among pre- and postmenopausal women, respectively; these associations were nonlinear. Compared with premenopausal women with a BMI of less than 21 kg/m2, women with a BMI exceeding 31 kg/m2 had an RR of 0.54 (95% CI: 0.34, 0.85). In postmenopausal women, the RRs did not increase further when BMI exceeded 28 kg/m2; the RR for these women was 1.26 (95% CI: 1.09, 1.46). The authors found little evidence for interaction with other breast cancer risk factors. Their data indicate that height is an independent risk factor for postmenopausal breast cancer; in premenopausal women, this relation is less clear. The association between BMI and breast cancer varies by menopausal status. Weight control may reduce the risk among postmenopausal women.     

Obesity and height in urban Nigerian women with breast cancer

PURPOSE: To examine the relationship between obesity, height, and breast cancer in an urban Nigerian population. METHODS: Between March 1998 and August 2000, we conducted a case-control study of hospital-based breast cancer patients (n = 234) and population-based controls (n = 273) using nurse interviewers in urban Southwestern Nigeria. RESULTS: The study did not find a significant association between obesity (BMI >/= 30) and breast cancer among all women (OR = 1.51, 95% CI = 0.87-2.62) pre- (OR = 1.21, 95% CI = 0.56-2.60) and post-menopausal breast cancer patients (OR = 1.82, 95% CI = 0.78-4.31) in multivariate logistic regression analysis, while increasing height was positively associated with the risk of breast cancer among all women (OR = 1.05, 1.01 - 1.08), pre- (1.06, 1.01-1.10) and post-menopausal women (1.07, 1.01-1.13) for each cm. Age, irregular period, and early age of onset of periods were also found to be significantly associated with breast cancer risk. CONCLUSION: This study failed to demonstrate an association between breast cancer risk and obesity while showing that height is positively associated with risk of breast cancer in urbanized Nigerian women.     

Body size and risk for breast cancer in relation to estrogen and progesterone receptor status in Japan

PURPOSE: The aim of this study is to examine the association of height, weight, and body mass index (BMI) with breast cancer and its hormone receptor-defined subtype in a low-risk population. METHODS: We identified 441 newly diagnosed cases of breast cancer during a 9.9-year follow-up of a population-based cohort consisting of 55,537 women aged 40 to 69 years. Body size was assessed by using a self-administered questionnaire. RESULTS: We found a significant positive association of height and marginally significant positive associations of weight and BMI with breast cancer in postmenopausal women. Weight and BMI were associated more strongly with estrogen receptor-positive (ER+) than ER-negative (ER-) breast cancer in postmenopausal women. BMI was related significantly to increased risk for ER+ (hazard ratio [HR] per BMI increment of 1 kg/m2, 1.08; 95% confidence interval [CI], 1.01-1.15), but not ER- breast cancer (HR per BMI increment of 1 kg/m2, 0.95; 95% CI, 0.84-1.06; p for difference of HRs=0.048). CONCLUSIONS: The present study suggests that height, weight, and BMI are associated with increased risk for breast cancer among postmenopausal women in Japan. The positive association of weight and BMI might be limited to ER+ breast cancer.     

Childhood growth and breast cancer

Adult height is known to be positively associated with breast cancer risk. The mechanism underlying this association is complex, since adult height is positively correlated with age at menarche, which in turn is negatively associated with breast cancer risk. The authors used prospective data from a British cohort of 2,547 girls followed from birth in 1946 to the end of 1999 to examine breast cancer risk in relation to childhood growth. As expected, adult height was positively associated with age at menarche and breast cancer. In childhood, cases were taller and leaner, on average, than noncases. Significant predictors of breast cancer risk in models containing all components of growth were height velocity at age 4-7 years (for a one-standard-deviation increase, odds ratio (OR) = 1.54, 95% confidence interval (CI): 1.13, 2.09) and age 11-15 years (OR = 1.29, 95% CI: 0.97, 1.71) and body mass index velocity (weight (kg)/height (m)(2)/year) at age 2-4 years (OR = 0.63, 95% CI: 0.48, 0.83). The effects of these variables were particularly marked in women with early menarche (age <12.5 years). These findings suggest that women who grow faster in childhood and reach an adult height above the average for their menarche category are at particularly increased risk of breast cancer.     

Breast cancer, lactation history, and serum organochlorines

The authors analyzed the relation between lactation history, organochlorine serum levels-in particular, 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE)-and the risk of breast cancer within a subsampe from a larger breast cancer case-control study conducted among women living in Mexico City, Mexico, between 1990 and 1995. From the original study, they selected a random sample of 260 subjects (1:1 case/control ratio). Analysis was restricted to 120 cases and 126 controls who had given birth to at least one child and had complete information on all key variables. Serum DDE levels were higher among cases (mean = 3.84 microg/g lipids, standard deviation = 5.98) than among controls (mean = 2.51 microg/g lipids, standard deviation = 1.97). After adjustment for age, age at menarche, duration of lactation, Quetelet index, and serum DDT levels, serum DDE levels were positively related to the risk of breast cancer (adjusted odds ratio (OR)Q1-Q2 = 1.24, 95% confidence interval (CI): 0.50, 3.06; ORQ1-Q3 = 2.31, 95% CI: 0.92, 5.86; ORQ1-Q4 = 3.81, 95% CI: 1.14, 12.80; test of trend, p = 0.02). The increased risk associated with higher serum DDE levels was more apparent among postmenopausal women (ORQ1-Q4 = 5.26, 95% CI: 0.80, 34.30; test of trend p = 0.03). A longer period of lactation was associated with a slightly decreased risk of breast cancer independently of serum DDE levels (OR = 0.91, 95% CI: 0.85, 0.99 change in risk per 10 months of lactation). Serum DDT level was not related to the risk of breast cancer. The data suggest that high levels of exposure to DDE may increase women's risk of breast cancer, particularly among postmenopausal women.     

Age and menopausal effects of hormonal birth control and hormone replacement therapy in relation to breast cancer risk

It is unclear whether breast cancer risk varies by age and menopausal status in relation to use of hormonal birth control (HBC) and hormone replacement therapy (HRT), taken singly or cumulatively. The authors utilized data from 1,478 cases and 1,493 controls aged 20-98 years with known menopausal status, who had participated in a population-based, case-control study conducted on Long Island during 1996-1997. Exogenous hormone use over the lifecourse was assessed by use of memory aids. The authors examined associations among women in these subgroups: premenopausal (n = 968), postmenopausal <65 years (n = 1,045), and postmenopausal > or = 65 years (n = 958). Among premenopausal women, risk was increased for ever use of HBC (odds ratio (OR) = 1.37, 95% confidence interval (CI): 1.04, 1.81) or HRT (OR = 1.81, 95% CI: 1.17, 2.81) and was pronounced among women reporting use of both HBC and HRT (OR = 2.59, 95% CI: 1.50, 4.46), long-term HRT use (OR = 3.93, 95% CI: 1.43, 10.84), or estrogen-plus-progestin therapy (OR = 3.51, 95% CI: 1.45, 8.49). There was no effect of ever HBC use among postmenopausal women aged less than 65 years, but risk was modestly elevated for more than 5 years of HRT use (OR = 1.41, 95% CI: 1.00, 1.99). Among postmenopausal women aged 65 years or more, odds ratios for HBC or HRT use were around the null. These results emphasize that timing of exogenous hormone use is important. Women who used these hormones before menopause had elevated risks, but the harmful effects began to decline with age after menopause.     

Case-control study of lifetime physical activity and breast cancer risk

A population-based case-control study of 1,233 incident breast cancer cases and 1,237 controls was conducted in Alberta, Canada, in 1995-1997 to examine the effect of lifetime physical activity patterns on breast cancer risk. No associations between physical activity and breast cancer were found for premenopausal women. For postmenopausal women in the highest quartile (> or =161 metabolic equivalent (MET)-hours/week per year) versus the lowest quartile (<104.8 MET-hours/week per year) of lifetime total physical activity, the adjusted odds ratio was 0.70 (95% confidence interval (CI): 0.52, 0.94). When the risks associated with each type of activity were examined for postmenopausal women, household and occupational activity conferred the largest risk reductions (odds ratio (OR) = 0.57, 95% CI: 0.41, 0.79 and OR = 0.59, 95% CI: 0.44, 0.81, respectively, for highest vs. lowest quartiles of activity), while recreational activity was not associated with any risk reductions. For postmenopausal women, the authors found stronger risk reductions for those who were also nonsmokers (OR = 0.64, 95% CI: 0.46, 0.88), non-alcohol-drinkers (OR = 0.39, 95% CI: 0.11, 0.77), or nulliparous (OR = 0.22, 95% CI: 0.07, 0.70) when they compared the highest with the lowest quartile of lifetime total physical activity. This study provides evidence that lifetime total activity reduces risk of postmenopausal breast cancer.     

Serum polychlorinated biphenyls, cytochrome P-450 1A1 polymorphisms, and risk of breast cancer in Connecticut women

Recent epidemiologic studies have suggested that genetic polymorphisms in the cytochrome P-450 1A1 gene (CYP1A1) may affect the relation between environmental exposure to polychlorinated biphenyls (PCBs) and breast cancer risk. The authors report results from a case-control study evaluating the potential effect of gene-environment interaction between CYP1A1 and serum PCB levels on breast cancer risk among Caucasian women in Connecticut. The study included 374 case women with histologically confirmed breast cancer and 406 noncancerous controls with information on both serum PCB level and CYP1A1 genotype (1999-2002). Compared with women who had the homozygous wild-type CYP1A1 m2 genotype, significantly increased risks of breast cancer were found for women with the CYP1A1 m2 variant genotype (odds ratio (OR) = 2.1, 95% confidence interval (CI): 1.1, 3.9), especially postmenopausal women (OR = 2.4, 95% CI: 1.1, 5.0). Risks associated with the CYP1A1 m2 variant genotype were highest for all women (OR = 3.6, 95% CI: 1.5, 8.2) and postmenopausal women (OR = 4.3, 95% CI: 1.6, 12.0) with higher serum PCB levels (611-2,600 ng/g). The CYP1A1 m1 and m4 genotypes were not associated with breast cancer risk independently or in combination with PCB exposure. In summary, the CYP1A1 m2 genetic polymorphism was associated with increased risk of female breast cancer and may modify the relation between PCB exposure and breast cancer risk.     

Associations of weight,weight change,and body mass with breast cancer risk in Hispanic and non-Hispanic white women

PURPOSE: A wealth of studies have examined the effects of weight, weight gain, and obesity on breast cancer risk; however, few have examined this relationship in Hispanic white women, a population with the highest rate of obesity in the U.S. METHODS: A population-based case-control study was conducted in New Mexico of Hispanic (n = 694) and non-Hispanic (n = 813) white women with incident breast cancer during the period of January 1, 1992 through December 31, 1994. Conditional logistic regression models were fitted to estimate the relative risk of breast cancer for levels of weight, weight change, and body mass index (BMI) and to assess differences in the effects by ethnicity, menopausal status, early life BMI, and estrogen receptor/progesterone receptor (ER/PR) expression in tumors. RESULTS: Weight change from age 18 to usual adult weight was associated with increased risk of breast cancer among Hispanics [4th quartile vs. baseline, odds ratio (OR): 2.41; 95% confidence interval (CI): 1.45-4.03] with no substantial variation by menopausal status. In non-Hispanic white women, weight change was a risk factor for those in the post-menopausal group (4th quartile vs. baseline, OR: 2.27; 95% CI: 1.09-4.73). The effect of usual BMI (test for interaction p = 0.04) and weight change (test for interaction p = 0.03) differed by ethnicity. Increased risk from weight gain was largely restricted to women who were lean at age 18 and those with ER(+)/PR(+) tumors. Height, weight at age 18, and BMI at age 18 were not associated with risk in either ethnic group. CONCLUSIONS: Weight change and obesity are risk factors for breast cancer in both Hispanic and non-Hispanic white women. However, the risk for Hispanic women is evident independent of menopausal status, while the risk for non-Hispanics is apparent in post-menopausal women. Due to the increasing prevalence of adult obesity, particularly among Hispanic women, adult weight gain may be an important modifiable risk factor for the primary prevention of breast cancer among Hispanic populations.     

Dietary glycemic index, glycemic load, and the risk of breast cancer in an Italian prospective cohort study

BACKGROUND: Interest in the roles of glycemic index (GI) and glycemic load (GL) in breast cancer etiology has been stimulated by indications that disease risk is linked to insulinemia, sex hormone bioavailability, and insulin-like growth factor 1. OBJECTIVE: We aimed to determine whether GI and GL were associated with the risk of breast cancer in a cohort of Italian women volunteers from Northern Italy, who enrolled between 1987-1992 in the Hormones and Diet in the Etiology of Breast Tumors Study (ORDET Study). DESIGN: Volunteers completed a semiquantitative food-frequency questionnaire, and anthropometric and lifestyle data were collected. Dietary GI and GL in relation to breast cancer risk were examined in 8926 cohort women, including 289 with breast cancer identified after a mean follow-up of 11.5 y. RESULTS: The relative risk (RR) of breast cancer in the highest (versus lowest) quintiles of GI and GL was 1.57 (95% CI: 1.04, 2.36; P for trend = 0.040) and 2.53 (95% CI: 1.54, 4.16; P for trend = 0.001), respectively. Total carbohydrate intake was not associated with greater breast cancer risk, but high carbohydrate from high-GI foods was. When women were categorized by baseline menopausal status and body mass index (BMI; in kg/m(2)), the increased risk of dietary GL was confined to those who were premenopausal (RR = 3.89; 95% CI: 1.81, 8.34) and who had normal BMI (ie, <25) (RR = 5.79; 95% CI: 2.60, 12.90) (P for trend = 0.001 for both). CONCLUSIONS: A high-GL diet may increase the risk of breast cancer in Italian women. The effect is particularly evident in premenopausal women and those with BMI < 25.     

Cigarette smoking and breast cancer.

An epidemiological case-control study was conducted in New York State, with 1617 primary breast cancer patients and an equal number of controls, to examine the relationship between cigarette smoking and breast cancer. Results showed no overall association between ever smokers versus never smokers and breast cancer risk (odds ratio [OR] = 1.03, 95% confidence interval [CI]: 0.90-1.19), nor was there any dose response trend observed with increased levels of smoking. In addition, no association was found with risk and age started smoking, age stopped smoking, amount smoked or total years smoked. Controlling for previously identified risk factors for breast cancer in the analysis did not significantly alter these relationships. Previous studies have found a difference in menopausal age among smokers compared to nonsmokers. The mean menopausal age was only slightly lower in smokers than in never smokers for both cases and controls. Breast cancer risk was observed to be close to unity for premenopausal women (OR = 0.97, 95% CI: 0.74-1.34) and postmenopausal women (OR = 1.06, 95% CI: 0.91-1.26). A recent study suggested breast cancer risk was more strongly related to starting smoking at a young age among women who smoked at least 25 or more cigarettes per day in the most recent year of smoking. This hypothesis was not supported by these data.     

Fruits, vegetables, soy foods and breast cancer in pre- and postmenopausal Korean women: a case-control study

We carried out a case-control study to examine the relationship between fruits, vegetables, and soy foods intake with breast cancer risk in Korean women. Incident cases (n = 359) were identified through cancer biopsies and hospital-based controls (n = 708) were selected in the same hospitals. Subjects were asked to indicate usual dietary habits, which were assessed using a semi-quantitative food frequency questionnaire (98 items). Odds ratio (OR) and 95% confidence intervals (95% CI) were calculated by unconditional logistic regression after adjustment for additional confounding factors according to the menopausal status. High grape intake showed an inverse association of breast cancer in postmenopausal women (OR = 0.59, 95% CI = 0.35-0.95; p for trend = 0.05). High tomato intake was associated with reduced breast cancer risk in premenopausal women (OR = 0.59, 95% CI = 0.38-0.89, p for trend = 0.04). In postmenopausal women, green pepper intake showed an inverse association of breast cancer risk (OR = 0.60, 95% CI = 0.43-0.96, p for trend = 0.03). High soybean intake showed an inverse association of breast cancer in postmenopausal women (OR = 0.61, 95% CI = 0.34-0.89, p for trend = 0.02). Our study suggests that high intake of some fruits, vegetables, and soybeans may be associated with a reduced breast cancer risk.     

Risk factors for breast cancer in elderly women

As the population ages, an increasing fraction of women diagnosed with breast cancer will be elderly. Heterogeneity of breast cancer risk factors between pre- and postmenopausal women is recognized, but few studies have examined elderly women specifically. The authors describe the age-specific influence of risk factors for postmenopausal breast cancer, with emphasis on women aged 75 or more years. Among 36,658 members of the Iowa Women's Health Study (1986-2001), a population-based cohort study, 428 incident breast cancers were diagnosed in women aged 55-64 years, 1,297 in women aged 65-74 years, and 561 in women aged 75-84 years. Women with a body mass index (weight (kg)/height (m)(2)) in the highest versus the lowest quartile were at increased risk of breast cancer at age 75 or more years (adjusted hazard ratio = 1.44, 95% confidence interval (CI): 1.12, 1.84). Family history of breast cancer (hazard ratio = 1.54, 95% CI: 1.24, 1.93 for a first-degree family history vs. none) and an older age at menopause (p(trend) = 0.07) conferred increased risk for women aged 75 or more years, and a high number of livebirths was protective (hazard ratio = 0.67, 95% CI: 0.51, 0.88 for five or more births compared with one or two). Obesity, a modifiable risk factor, remained positively associated with breast cancer for all age groups of postmenopausal women.     

Hormone-related factors and risk of breast cancer in relation to estrogen receptor and progesterone receptor status

Risk factors were examined for subgroups of breast cancer characterized by estrogen receptor (ER) and progesterone receptor (PR) status. Data from the Carolina Breast Cancer Study, a population-based, North Carolina case-control study of 862 breast cancer cases aged 20-74 years diagnosed during 1993-1996 and 790 controls frequency matched on race and age, were obtained by personal interview. ER and PR status was retrieved from medical records (80%) or was determined in the authors' laboratory (11%) but was missing for 9% of cases. The receptor status distribution was as follows: 53% ER+PR+, 11% ER+PR-, 8% ER-PR+, and 28% ER-PR-. Several hormone-related factors were associated with stronger increased risks for ER+PR+ than for ER-PR- breast cancer: the elevated odds ratios were strongest for ER+PR+ breast cancer among postmenopausal women who had an early age at menarche (odds ratio (OR) = 1.6, 95% confidence interval (CI): 1.0, 2.4), nulliparity/late age at first full-term pregnancy (OR = 1.7, 95% CI: 0.9, 3.2 and OR = 1.6, 95% CI: 1.0, 2.7, respectively), or a high body mass index (OR = 1.6, 95% CI: 0.9, 3.0) and among pre-/perimenopausal women who had a high waist-hip ratio (OR = 1.9, 95% CI: 1.2, 3.1). In contrast, family history of breast or ovarian cancer and medical radiation exposure to the chest produced higher odds ratios for ER-PR- than for ER+PR+ breast cancer, especially among pre-/perimenopausal women.     

Body mass index and breast cancer risk in African American women

PURPOSE: Studies of the relationship between body mass index (BMI) and breast cancer in African American women have been few. We conducted a case-control study to examine whether BMI is associated with risk of breast cancer in this population. METHODS: Cases were 304 women diagnosed with breast cancer at the ages of 20 to 64 years. Controls were 305 women without a history of breast cancer. Telephone interviews were conducted to collect data on history of exposure to various factors at or before the date of diagnosis in cases or equivalent date in controls (reference date). Using logistic regression, we compared cases and controls in BMI at age 18, BMI at the reference date, and change in BMI between the two dates. RESULTS: Using BMI at reference date, we found an odds ratio (OR) of 1.75 (95% confidence interval [CI], 1.02-3.02) and 2.32 (95% CI, 1.33-4.03) for women with BMI of 25 to 29.9 and 30 or higher, respectively, compared with women having BMI lower than 25. The corresponding OR estimates for BMI at age 18 were not significantly different from the unity. The average annual change in BMI between age 18 and date of diagnosis or reference date was associated with breast cancer risk, as shown that more BMI change tended to increase breast cancer risk compared with the baseline quartile of change. When data were analyzed by menopausal status, the association was found for both post-menopausal and pre-menopausal tumors for BMI at reference date but not for BMI at age 18. There was a higher risk for more annual BMI change compared with the baseline for both pre-menopausal and post-menopausal women. CONCLUSION: Our results suggest that BMI at reference date and change in BMI were associated with increased risk of breast cancer in African American women, and the association might be found for both post-menopausal and pre-menopausal tumors.     

Cruciferous vegetables, the GSTP1 Ile105Val genetic polymorphism, and breast cancer risk

BACKGROUND: Cruciferous vegetables are the primary source of isothiocyanates and other glucosinolate derivatives that are known to induce phase II detoxifying enzymes, including glutathione S-transferases (GSTs). OBJECTIVE: We investigated the independent and combined effects of cruciferous vegetable intake and the GSTP1 Ile(105)Val genetic polymorphism on breast cancer risk. DESIGN: Analyses included 3035 cases and 3037 population controls who were participating in the Shanghai Breast Cancer Study and for whom diet and genetic data were complete (87% of cases and 85% of controls). RESULTS: With the use of multivariate logistic regression, the GSTP1 Val/Val genotype was significantly associated with greater breast cancer risk (OR = 1.50; 95% CI: 1.12, 1.99). The association was significantly greater in premenopausal women (OR = 1.69; 95% CI: 1.17, 2.43) than in postmenopausal women (OR = 1.20; 95% CI: 0.74, 1.92). Total cruciferous vegetable intake was not significantly associated with breast cancer risk, although subjects reporting greater turnip (P for trend < 0.001) and Chinese cabbage (P for trend = 0.049) intakes had a significantly lower postmenopausal breast cancer risk. Women with the GSTP1 Val/Val genotype and low cruciferous vegetable intake had a breast cancer risk 1.74-fold (95% CI: 1.13, 2.67) that of women with the Ile/Ile or Ile/Val genotype. This effect of low cruciferous vegetable intake and the Val/Val genotype was seen predominantly among premenopausal women (OR = 2.08; 95% CI = 1.20, 3.59). CONCLUSIONS: Cruciferous vegetable intake consistent with high isothiocyanate exposure may reduce breast cancer risk. Cruciferous vegetable intake also may ameliorate the effects of the GSTP1 genotype.     

Body size in early life and adult levels of insulin-like growth factor 1 and insulin-like growth factor binding protein 3

Body size in early life has been associated with breast cancer risk. This may be partly mediated through the insulin-like growth factor (IGF) pathway. The authors assessed whether birth weight, body fatness at ages 5 and 10 years, and body mass index (BMI; weight (kg)/height (m)(2)) at age 18 years were associated with plasma concentrations of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 in 6,520 women aged 32-70 years at blood draw from the Nurses' Health Study (1990-2006) and Nurses' Health Study II (1997-2005). Birth weight, body fatness in childhood, and BMI at age 18 years were inversely associated with adult IGF-1 levels. For example, IGF-1 levels were 11.9% lower in women who reported being heaviest at age 10 years than in those who were leanest at age 10 (P-trend < 0.0001). Further, women who reported their birth weight as ≥10 pounds (≥4.5 kg) (vs. <5.5 pounds (<2.5 kg)) had 7.9% lower IGF-1 levels (P-trend = 0.002). Women whose BMI at age 18 years was ≥30 (vs. <20) had 14.1% lower IGF-1 levels (P-trend < 0.0001). Similar inverse associations were observed for insulin-like growth factor binding protein 3. These observations did not vary by adult BMI or menopausal status at blood draw. These findings suggest that altered IGF-1 levels in adulthood may be a mechanism through which early-life body size influences subsequent breast cancer risk.     

Dietary flavonoid intake and breast cancer risk among women on Long Island

Flavonoids are found in a variety of foods and have anticarcinogenic properties in experimental models. Few epidemiologic studies have examined whether flavonoid intake is associated with breast cancer in humans. In this study, the authors investigated whether dietary flavonoid intake was associated with reduced risk of breast cancer in a population-based sample of US women. They conducted a case-control study among women who resided in Nassau and Suffolk counties on Long Island, New York. Cases and controls were interviewed about known and suspected risk factors and asked to complete a food frequency questionnaire regarding their average intake in the prior 12 months. A total of 1,434 breast cancer cases and 1,440 controls provided adequate responses. A decrease in breast cancer risk was associated with flavonoid intake; the decrease was most pronounced among postmenopausal women for flavonols (odds ratio (OR) = 0.54, 95% confidence interval (CI): 0.40, 0.73), flavones (OR = 0.61, 95% CI: 0.45, 0.83), flavan-3-ols (OR = 0.74, 95% CI: 0.55, 0.99), and lignans (OR = 0.69, 95% CI: 0.51, 0.94). The authors conclude that intake of flavonols, flavones, flavan-3-ols, and lignans is associated with reduced risk of incident postmenopausal breast cancer among Long Island women. These results suggest that US women can consume sufficient levels of flavonoids to benefit from their potential chemopreventive effects.