Risk factors for breast cancer in East Asian women relative to women in the West

The incidence of breast cancer in women of East Asian ancestry (Chinese, Japanese and Korean) is lower than in women of European ancestry but is currently rising. This review explores potential reasons for this inter‐ethnic difference in incidence by profiling breast cancer risk factors reported for East Asian and Western women. Factors such as endogenous hormone exposure, lifestyle choices, diet and genetic predisposition are associated with breast cancer risk in both East Asian and Western women. However, the relative exposure to these risk factors may vary according to a woman's geographical ancestry and culture. For example, age at menarche and menopause, parity, breast‐feeding history, low fat and high soy consumption as well as the prevalence of high risk genetic alleles may vary with a woman's geographical ancestry and/or culture. Differences in exposure to these risk factors in East Asian and Western women are consistent with the inter‐ethnic differences in breast cancer incidence observed. Understanding the underlying factors contributing to differences in the profile of breast cancer across populations is important when considering screening and prevention programs for East Asian women resident in the East or the West.     

Prospective study of alcohol consumption and breast cancer risk in Japanese women

Epidemiologic evidence is lacking for the association between alcohol consumption and the risk of breast cancer in Japanese women. We addressed this association in a prospective cohort study with an average follow-up of 7.6 years. At baseline (1988-1990), cohort participants completed a self-administered questionnaire that included alcohol use, reproductive history and hormone use. The women were followed up for breast cancer incidence through December 31, 1997. Cox proportional hazards models were used to calculate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer incidence and any association with alcohol consumption. During a follow-up of 271,412 person-years, we identified 151 women with breast cancer, of whom 45 were current drinkers and 11 drank > or =15 g of alcohol/day. After adjustment for age and other potential risk factors for breast cancer, the RR for current drinkers was 1.27 (95% CI 0.87-1.84) compared to nondrinkers. Average alcohol intake of <15 g/day did not significantly increase the risk for breast cancer. However, risk was significantly increased for women who consumed > or =15 g/day of alcohol (RR = 2.93, 95% CI 1.55-5.54). Age at starting drinking and frequency of consumption per week were not significantly associated with breast cancer risk. Our cohort study demonstrated that Japanese women who consume at least a moderate amount of alcohol have an increased risk of breast cancer.     

Effect of obesity and other lifestyle factors on mortality in women with breast cancer

A few lifestyle characteristics before cancer diagnosis have been suggested to modify the prognosis of breast cancer. Follow-up information from 1,453 women with incident invasive breast cancer, diagnosed between 1991 and 1994 and interviewed within the framework of an Italian multicenter case-control study, was used to assess the effect of obesity and of a large spectrum of other factors on breast cancer mortality. Five hundred and three deaths, including 398 breast cancer deaths, were identified. Hazard ratios (HR) for all-cause and breast cancer mortality and corresponding 95% confidence intervals (CI), were calculated using Cox proportional hazards models and adjusted for age and breast cancer characteristics (stage and receptor status). Increased risk of death for breast cancer emerged for body mass index (BMI) >/= 30 kg/m(2) (HR = 1.38; 95% CI: 1.02-1.86), compared to <25, or waist-to-hip ratio (WHR) >/= 0.85 (HR = 1.27; 95% CI: 0.98-1.64), compared to <0.80, and the strongest association was observed for women with BMI >/=30 and high WHR (>/=0.85), compared to women with BMI <25 and WHR < 0.85 (HR = 1.57, 95% CI: 1.08-2.27). The unfavorable effect of high BMI was similar in women <55 and >/=55 years of age, whereas it was stronger in women with I-II stage than III-IV stage breast cancer. Low vegetable and fruit consumption and current or past smoking were also associated to marginally worse breast cancer survival. No significant relationship with survival after breast cancer emerged for several other major lifestyle factors, including physical activity, alcohol drinking, exogenous hormones use and fat intake. High BMI was the lifestyle risk factor that most consistently modified breast cancer prognosis in our study.     

Alcohol,tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies,including 58,515 women with breast cancer and 95,067 women without the disease

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.     

Healthy lifestyle and risk of breast cancer among postmenopausal women in the European Prospective Investigation into Cancer and Nutrition cohort study

Breast cancer is the most common cancer among women and prevention strategies are needed to reduce incidence worldwide. A healthy lifestyle index score (HLIS) was generated to investigate the joint effect of modifiable lifestyle factors on postmenopausal breast cancer risk. The study included 242,918 postmenopausal women from the multinational European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, with detailed information on diet and lifestyle assessed at baseline. The HLIS was constructed from five factors (diet, physical activity, smoking, alcohol consumption and anthropometry) by assigning scores of 0–4 to categories of each component, for which higher values indicate healthier behaviours. Hazard ratios (HR) were estimated by Cox proportional regression models. During 10.9 years of median follow‐up, 7,756 incident breast cancer cases were identified. There was a 3% lower risk of breast cancer per point increase of the HLIS. Breast cancer risk was inversely associated with a high HLIS when fourth versus second (reference) categories were compared [adjusted HR = 0.74; 95% confidence interval (CI): 0.66–0.83]. The fourth versus the second category of the HLIS was associated with a lower risk for hormone receptor double positive (adjusted HR = 0.81, 95% CI: 0.67–0.98) and hormone receptor double negative breast cancer (adjusted HR = 0.60, 95% CI: 0.40–0.90). Findings suggest having a high score on an index of combined healthy behaviours reduces the risk of developing breast cancer among postmenopausal women. Programmes which engage women in long term health behaviours should be supported.     

Alcohol and breast cancer risk — putting the current controversy into perspective

The potential association of alcohol intake with breast cancer risk is currently being debated in the literature and a clear consensus of opinion has not emerged. Clarification of the issues surrounding this controversy would be helpful in developing recommendations for the general public regarding alcohol use. A review of the available evidence regarding the association of alcohol with breast cancer is presented followed by an application of the Bradford Hill criteria for causal inference to this data to examine the existence and nature of the association of alcohol with breast cancer risk.Results of published studies demonstrated a weak association of alcohol with breast cancer risk that was consistent only for relatively high levels of intake (more than 1 or 2 drinks daily). Increasing daily intake was associated with increased risk, but the association was not linear. Criteria relating to temporality and analogy to other causal associations were satisfied while inconsistent evidence was available for those relating to epidemiologic and biologic sense. The criterion for specificity was not satisfied and no experimental evidence was available.It is concluded that insufficient evidence exists to support a causal association of alcohol consumption with breast cancer risk. Further research is recommended to resolve conflicting evidence and to provide additional evidence where needed. In the meantime, recommendations that women should reduce their consumption of alcohol beyond existing guidelines to modify breast cancer risk are probably premature.Dr. Goodwin is a Career Scientist of the Ontario Ministry of Health.     

Green tea and risk of breast cancer in Asian Americans

There is substantial in vitro and in vivo evidence implicating tea polyphenols as chemopreventive agents against various cancers. However, epidemiologic data obtained from mainly Western populations are not supportive of a protective role of tea, mainly black tea, in the etiology of breast cancer. Much less is known about the relationship between green tea and breast cancer risk. During 1995-1998, we conducted a population-based, case-control study of breast cancer among Chinese, Japanese and Filipino women in Los Angeles County and successfully interviewed 501 breast cancer patients and 594 control subjects. Detailed information on menstrual and reproductive factors; dietary habits, including intake of black and green tea; and other lifestyle factors was collected. Risk of breast cancer was not related to black tea consumption. In contrast, green tea drinkers showed a significantly reduced risk of breast cancer, and this was maintained after adjusting for age, specific Asian ethnicity, birthplace, age at menarche, parity, menopausal status, use of menopausal hormones, body size and intake of total calories and black tea. Compared to women who did not drink green tea regularly (i.e., less than once a month), there was a significant trend of decreasing risk with increasing amount of green tea intake, adjusted odds ratios being 1.00, 0.71 (95% confidence interval [CI] 0.51-0.99) and 0.53 (95% CI 0.35-0.78), respectively, in association with no, 0-85.7 and >85.7 ml of green tea per day. The significant inverse association between risk of breast cancer and green tea intake remained after further adjustment for other potential confounders, including smoking; alcohol, coffee and black tea intake; family history of breast cancer; physical activity; and intake of soy and dark green vegetables. While both green tea and soy intake had significant, independent protective effects on breast cancer risk, the benefit of green tea was primarily observed among subjects who were low soy consumers. Similarly, the protective effect of soy was primarily observed among subjects who were nondrinkers of green tea. In summary, our results point to an important role of both green tea and soy intake in relation to breast cancer risk in Asian-American women.     

Pre‐diagnostic alcohol consumption and breast cancer recurrence and mortality: Results from a prospective cohort with a wide range of variation in alcohol intake

The association between pre‐diagnostic alcohol consumption and breast cancer recurrence and breast cancer specific mortality was investigated in 1,052 women diagnosed with early breast cancer in a prospective cohort of 29,875 women. Known clinical, lifestyle and socioeconomic risk factors were evaluated and adjusted for in multivariate analysis. We found a modest but significant association between pre‐diagnostic alcohol consumption and breast cancer recurrence with a median follow‐up of six years after date of diagnosis, both when using baseline measures of alcohol intake (HR, 1.65; 95% CI, 1.02–2.67; >2 units/day vs. ≤1 unit/day) and cumulated alcohol intake (HR, 2.02; 95% CI, 1.06–3.85; >40 drinking years vs. 0<drinking years≤10). Results for breast cancer specific mortality were also suggestive of a higher risk but were not statistically significant. In addition to being a risk factor for breast cancer, a high pre‐diagnostic alcohol intake also seems to have an effect on the course of the disease. We could not relate the finding to a specific tumor presentation.     

Fiber intake modulates the association of alcohol intake with breast cancer

Alcohol intake has been related to an increased risk of breast cancer (BC) while dietary fiber intake has been inversely associated to BC risk. A beneficial effect of fibers on ethanol carcinogenesis through their impact on estrogen levels is still controversial. We investigated the role of dietary fiber as a modifying factor of the association of alcohol and BC using data from the European Prospective Investigation into Cancer and Nutrition (EPIC). This study included 334,850 women aged 35–70 years at baseline enrolled in the ten countries of the EPIC study and followed up for 11.0 years on average. Information on fiber and alcohol intake at baseline and average lifetime alcohol intake were calculated from country‐specific dietary and lifestyle questionnaires. Hazard ratios (HR) of developing invasive BC according to different levels of alcohol and fiber intake were computed. During 3,670,439 person‐years, 11,576 incident BC cases were diagnosed. For subjects with low intake of fiber (<18.5 g/day), the risk of BC per 10 g/day of alcohol intake was 1.06 (1.03–1.08) while among subjects with high intake of fiber (>24.2 g/day) the risk of BC was 1.02 (0.99–1.05) (test for interaction p = 0.011). This modulating effect was stronger for fiber from vegetables. Our results suggest that fiber intake may modulate the positive association of alcohol intake and BC. Alcohol is well known to increase the risk for BC, while a fiber‐rich diet has the opposite effect. Here the authors find a significant interaction between both lifestyle factors indicating that high fiber intake can ease the adverse effects associated with alcohol consumption. Consequently, women with high alcohol intake and low fiber intake (<18.5 g/day) had the highest risk for BC. Specific benefits were associated with fibers from vegetable, warranting further investigations into specific fiber sources and their mechanistic interactions with alcohol‐induced BC risk.     

Interaction between alcohol dehydrogenase II gene,alcohol consumption,and risk for breast cancer

MaeIII Restriction Fragment Length Polymorphism in exon 3 of the alcohol dehydrogenase II was assessed in serum from 467 randomly selected German women and 278 women with invasive breast cancer to evaluate the interaction between a polymorphism of the alcohol dehydrogenase II gene, alcohol consumption and risk for breast cancer. In both groups, usual consumption of different alcoholic beverages was asked for using semiquantitative food frequency questionnaires. We used multivariable logistic regression to separately estimate the association between alcohol consumption and alcohol dehydrogenase II polymorphism in the population sample and women with breast cancer. The alcohol dehydrogenase II polymorphism was detected in 14 women from the population sample (3.0%) and in 27 women with invasive breast cancer (9.7%). Frequency of alcohol consumption was independent of the genotype in the population sample. In women with breast cancer, there was a significant inverse association between the alcohol dehydrogenase II polymorphism and frequency of alcohol consumption (adjusted case-only odds ratio over increasing frequency of alcohol consumption=0.5; P for interaction=0.02). We observed a gene-environment interaction between the alcohol dehydrogenase II polymorphism, alcohol consumption, and risk for breast cancer. Breast cancer risk associated with alcohol consumption may vary according to the alcohol dehydrogenase II polymorphism, probably due to differences in alcohol metabolism.     

Association of Lifestyle and Other Risk Factors with Breast Cancer According to Menopausal Status: A Case-Control Study in the Region of WesternPomerania (Poland).

Purposes: The purpose of this study was to examine the association between family history, reproductive, anthropometric, lifestyle factors and risk of breast cancer according to menopausal status, using data from a case-control study conducted in the Region of Western Pomerania (Poland). Methods: A total, 858 women with histological confirmed breast cancer and 1085 controls, free of any cancer diagnosis, aged 28-78 years, were included in the study. The study was based on a self-administered questionnaire. Logistic regression was used to compute odds ratios and 95% confidence intervals and a broad range of potential confounders was included in analysis. Results: Protective effect of a late age at menarche, a longer period of breast-feeding, increased levels of: recreational physical activity, total vegetables or fruits intake, and intake of vitamins on the risk of breast cancer was observed among both pre- and post-menopausal women. Familial history of breast cancer, active or passive smoking, experience of a crude psychological stress were positively associated with breast cancer regardless menopausal status. Current body weight, current body mass index, increased alcohol intake elevated breast cancer risk in postmenopausal women, while these factors did not alter risk among premenopausal women. Increased consumption of red meat or animal fats elevated the risk in premenopausal women. More educated premenopausal women had lower breast cancer than those graduated from elementary school. Low family income increased the risk in premenopausal women. Conclusion: There is evidence for a dose-response relationship between several lifestyle factors and breast cancer risk. The results also suggest that some different mechanisms may operate in breast cancer etiology in pre-and post-menopausal women. A multifactorial process of breast cancer development, the complex interaction between physical activity, diet, energy intake and body weight, inconsistent and inconclusive data on breast cancer risk factors coming even from well-designed epidemiological studies are the case for continual update knowledge on primary prevention and identification of changes in behavior that will reduce the risk.     

Background risk of breast cancer influences the association between alcohol consumption and mammographic density

Background:

Alcohol consumption has been suggested to increase risk of breast cancer through a mechanism that also increases mammographic density. Whether the association between alcohol consumption and mammographic density is modified by background breast cancer risk has, however, not been studied.

Methods:

We conducted a population-based cross-sectional study of 53 060 Swedish women aged 40–74 years. Alcohol consumption was assessed using a web-based self-administered questionnaire. Mammographic density was measured using the fully-automated volumetric Volpara method. The Tyrer–Cuzick prediction model was used to estimate risk of developing breast cancer in the next 10 years. Linear regression models were used to evaluate the association between alcohol consumption and volumetric mammographic density and the potential influence of Tyrer–Cuzick breast cancer risk.

Results:

Overall, increasing alcohol consumption was associated with higher absolute dense volume (cm³) and per cent dense volume (%). The association between alcohol consumption and absolute dense volume was most pronounced among women with the highest (⩾5%) Tyrer–Cuzick 10-year risk. Among high-risk women, women consuming 5.0–9.9, 10.0–19.9, 20.0–29.9, and 30.0–40.0 g of alcohol per day had 2.6 cm³ (95% confidence interval (CI), 0.2–4.9), 2.9 cm³ (95% CI, −0.6 to 6.3), 4.6 cm³ (95% CI, 1.5–7.7), and 10.8 cm³ (95% CI, 4.8–17.0) higher absolute dense volume, respectively, as compared with women abstaining from alcohol. A trend of increasing alcohol consumption and higher absolute dense volume was seen in women at low (⩽3%) risk, but not in women at moderate (3.0–4.9%) risk.

Conclusion:

Alcohol consumption may increase breast cancer risk through increasing mammographic density, particularly in women at high background risk of breast cancer.     

Lifestyle Components and Primary Breast Cancer Prevention

Breast cancer primary prevention is a high research priority due to the high psychological and economic costs.The disease is a multistep process and several risk factors have been recognized. Over the past three decadesnumerous studies have investigated the association of lifestyle with breast cancer, showing independent effects ofvarious factors. We report here a summary of the present state of knowledge on the role of lifestyle patterns, suchas physical activity, diet, smoking, hormone therapy, and experience of psychological stress in the modulation ofbreast cancer in women, and discuss commonly accepted biological mechanisms hypothesized as responsible forthe associations. The findings indicate that regular physical activity of moderate to vigorous intensity is probablylinked with the decreased breast cancer risk among postmenopausal females and suggestive for a decrease of therisk in premenopausal women. In contrast, the consumption of high-fat diet, alcohol intake, and use of combinedestrogen and synthetic progestagen hormonal therapy may increase the risk. Epidemiological findings dealingwith a role of smoking and experience of psychological stress are conflicting.     

The interaction between early‐life body size and physical activity on risk of breast cancer

While early‐life body leanness is associated with increased breast cancer risk, early‐life physical activity may protect against breast cancer. We examined whether the excess risk among lean girls is modified by their levels of prior, concurrent, or future physical activity. We conducted an analysis among 74,723 women in the Nurses' Health Study II (follow‐up 1997–2011). Participants recalled their body size at ages 5, 10 and 20 years in 1989 using a 9‐level pictogram (Level 1 most lean). In 1997, they reported adolescent levels of physical activity (ages 12–13 and 14–17 years). Cox proportional hazards models estimated the overall association of body size with breast cancer risk and assessed interactions of adolescent physical activity with body size at three different age periods (5–10, 10–20 and 20 years), adjusting for early‐life and adult risk factors for breast cancer. Regardless of levels of adolescent physical activity, early‐life body leanness (level 1–2 vs. 4.5+) was significantly associated with higher breast cancer risk. The association was slightly attenuated among those who were active (60+ MET‐hr/wk) during adolescence compared to those who were inactive (<30 MET‐hr/wk) (body size at ages 5–10 years: hazard ratio = 1.37, 95% confidence interval = 1.04–1.81 vs. 1.66, 1.29–2.12), but the interaction was not significant (p = 0.72). The results were similar for body size at three different age periods. Being lean during early life is a risk factor for breast cancer among both inactive and active girls. Adolescent physical activity did not significantly modify the association, although some interaction cannot be excluded.     

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.     

Adherence to the World Cancer Research Fund/American Institute for Cancer Research recommendations and breast cancer risk

The World Cancer Research Fund/American Association for Cancer Research (WCRF/AICR) has published eight nutrition‐related recommendations for the prevention of cancer. However, few prospective studies have examined these recommendations by breast cancer hormone receptor subtype and only one case–control study has included the dietary supplements recommendation in their evaluation. We investigated whether adherence to the WCRF/AICR cancer prevention recommendations was associated with breast cancer incidence, overall and by hormone receptor subtype, in the Swedish Mammography Cohort. Among 31,514 primarily postmenopausal women diet and lifestyle factors were assessed with a self‐administered food frequency questionnaire. A score was constructed based on adherence to the recommendations for body fatness, physical activity, energy density, plant foods, animal foods, alcoholic drinks and dietary supplements (score range 0–7). Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs). During 15 years of follow‐up 1,388 cases of breast cancer were identified. Women who met six to seven recommendations had a 51% decreased risk of breast cancer compared to women meeting only zero to two recommendations (95% CI = 0.35–0.70). The association between each additional recommendation met and breast cancer risk was strongest for the ER‐positive/PR‐positive subtype (HR = 0.86; 95% CI = 0.79–0.94), while for the ER‐negative/PR‐negative subtype the individual recommendations regarding plant and animal foods were most strongly associated with reduced risk. Our findings support that adherence to the WCRF/AICR recommendations reduces breast cancer risk in a population of primarily postmenopausal women. Promoting these recommendations to the public could help reduce breast cancer incidence.     

Alcohol,smoking, and risk of Her2‐overexpressing and triple‐negative breast cancer relative to estrogen receptor‐positive breast cancer

Epidemiological evidence is limited on how alcohol consumption and smoking are associated with risk of different subtypes of breast cancer, such as triple‐negative (TN) and human epidermal growth factor receptor 2‐overexpressing (H2E) breast cancers, which may have different etiologies from more common luminal (estrogen receptor [ER+]) breast cancers. In this population‐based case‐case study, we evaluated the association between alcohol, smoking, and risk of H2E and TN breast cancer, compared with ER+ breast cancers, among women aged 20–69 years. Using polytomous regression, associations between alcohol consumption, smoking, and breast cancer risk were evaluated in 909 ER+, 1,290 TN, and 489 H2E breast cancer patients, with ER+ breast cancer patients as the reference group. Current alcohol consumption at diagnosis was associated with a lower risk of H2E breast cancer (odds ratio = 0.74, 95% confidence interval: 0.58–0.92) relative to ER+ cancers. No difference in association was observed by menopausal status. No association between alcohol consumption and TN breast cancer relative to ER+ breast cancer was observed. Women who smoked did not have an altered risk of TN or H2E breast cancer, relative to ER+ cancer. Our results suggest that alcohol is associated with lower risk of H2E breast cancer relative to ER+ breast cancer. This study adds to the body of epidemiologic evidence that breast cancer etiology differs by breast cancer subtype.     

Association of mammographically defined percent breast density with epidemiologic risk factors for breast cancer (United States)

Objective: Mammographically defined percent breast density is an important risk factor for breast cancer, but the epidemiology of this trait is poorly understood. Although several studies have investigated the associations between reproductive factors and density, few data are available on the associations of breast density and waist-to-hip ratio (WHR), physical activity, education, alcohol and smoking. Methods: We investigated the associations of known and suspected breast cancer risk factors with breast density in a large breast cancer family study. Information was collected on members of 426 families through telephone interviews, mailed questionnaires and mammography. Mammographic films on 1900 women were digitized and breast density was estimated in discrete five-unit increments by one radiologist. Analysis of covariance techniques were used and all analyses were performed stratified by menopausal status. Results: Similar to other reports, nulliparity, late age at first birth, younger age and lower body mass index were associated with increased percent density in both premenopausal and postmenopausal women, and hormone replacement therapy among postmenopausal women. Higher levels of alcohol consumption and low WHR were associated with increased percent density among both premenopausal and postmenopausal women (differences of 3–11% between high and low categories). However, smoking and education were inversely associated with percent density among premenopausal (p = 0.004 and p = 0.003, respectively) but not postmenopausal women (p = 0.52 and p = 0.90). Physical activity was not associated with percent density in either stratum (p values > 0.25). Combined, these factors explained approximately 37% of the variability in the percent density measure in premenopausal women and 19% in postmenopausal women. Conclusions: Many of these factors may potentially affect breast cancer risk through their effect on percent breast density.     

Poor physical health predicts time to additional breast cancer events and mortality in breast cancer survivors

Background: Health‐related quality of life has been hypothesized to predict time to additional breast cancer events and all‐cause mortality in breast cancer survivors. Methods: Women with early‐stage breast cancer (n=2967) completed the SF‐36 (mental and physical health‐related quality of life) and standardized psychosocial questionnaires to assess social support, optimism, hostility, and depression prior to randomization into a dietary trial. Cox regression was performed to assess whether these measures of quality of life and psychosocial functioning predicted time to additional breast cancer events and all‐cause mortality; hazard ratios were the measure of association. Results: There were 492 additional breast cancer events and 301 deaths occurred over a median 7.3 years (range: 0.01–10.8 years) of follow‐up. In multivariate models, poorer physical health was associated with both decreased time to additional breast cancer events and all‐cause mortality (p trend=0.005 and 0.004, respectively), while greater hostility predicted additional breast cancer events only (p trend=0.03). None of the other psychosocial variables predicted either outcome. The hazard ratios comparing persons with poor (bottom two quintiles) to better (top three quintiles) physical health were 1.42 (95% CI: 1.16, 1.75) for decreased time to additional breast cancer events and 1.37 (95% CI: 1.08, 1.74) for all‐cause mortality. Potentially modifiable factors associated with poor physical health included higher body mass index, lower physical activity, lower alcohol consumption, and more insomnia (p<0.05 for all). Conclusion: Interventions to improve physical health should be tested as a means to increase time to additional breast cancer events and mortality among breast cancer survivors. Copyright © 2010 John Wiley & Sons, Ltd.     

Husband's smoking status and breast cancer risk in Japan: From the Takayama study

The effects of smoking on breast cancer remain unclear. We assessed the associations of subjects' or husbands' smoking status with breast cancer incidence in a population‐based prospective study in Japan. The subjects were 15 719 women aged 35 years or older. The follow up was conducted from September 1992 to March 2008. Cancer incidence was mainly confirmed through regional population‐based cancer registries. Breast cancer was defined as code C50 according to the International Classification of Diseases and Health Related Problems, 10th Revision. Lifestyle, including smoking status, was assessed with a self‐administered questionnaire. Alcohol consumption was assessed with a validated food‐frequency questionnaire. After multivariate adjustments for age, body mass index, alcohol consumption, physical activity, education, age at menarche, age at first delivery, menopausal status, number of children and history of hormone replacement therapy, active smoking was not associated with the risk of breast cancer. Compared with never smokers whose husband had never smoked, the risks of breast cancer were 1.98 (95% CI: 1.03–3.84) among never smokers whose husband was a current smoker of 21 cigarettes per day or more. The increased risk of breast cancer among women having a smoking husband was pronounced among those who did not habitually consume alcohol. These results suggest that exposure to smoke from husbands is a potential risk factor for breast cancer. The impact of alcohol consumption on the increased breast cancer risk from passive smoking needs to be addressed in further studies.