Caffeine consumption and the risk of breast cancer in a large prospective cohort of women

Maternal smoking, consumption of alcohol, and caffeinated beverages during pregnancy and the risk of childhood brain tumors: a meta-analysis of observational studies

BACKGROUND

We conducted this meta-analysis to investigate the potential association between maternal smoking, alcohol and caffeinated beverages consumption during pregnancy and the risk of childhood brain tumors (CBTs).

METHODS

A thorough search was carried out on PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Internet to identify pertinent articles. Fixed or random effects model was applied to meta-analyze the data.

RESULTS

The results suggested a borderline statistically significant increased risk of CBTs associated with maternal smoking during pregnancy (OR 1.04, 95% CI 0.99-1.09). We found that passive smoking (OR 1.12, 95% CI 1.03-1.20), rather than active smoking (OR 1.00, 95% CI 0.93-1.07), led to an increased risk of CBTs. The results suggested a higher risk in 0-1 year old children (OR 1.21, 95% CI 0.94-1.56), followed by 0-4 years old children (OR 1.12, 95% CI 0.97-1.28) and 5-9 years old children (OR 1.11, 95% CI 0.95-1.29). This meta-analysis found no significant association between maternal alcohol consumption during pregnancy and CBTs risk (OR 1.00, 95% CI 0.80-1.24). An increased risk of CBTs was found to be associated with maternal consumption of caffeinated beverages (OR 1.16, 95% CI 1.07-1.26) during pregnancy, especially coffee (OR 1.18, 95% CI 1.00-1.38).

CONCLUSIONS

Maternal passive smoking, consumption of caffeinated beverages during pregnancy should be considered as risk factors for CBTs, especially glioma. More prospective cohort studies are warranted to provide a higher level of evidence.

Associations of coffee/caffeine consumption with postmenopausal breast cancer risk and their interactions with postmenopausal hormone use

PURPOSE

We investigated the association of coffee and caffeine with breast cancer (BCa) risk, overall and by ER/PR status. We also examined potential interactions of coffee and caffeine with postmenopausal hormone use.

METHODS

Our study included 77,688 postmenopausal participants from the Women's Health Initiative observational study cohort without a history of any cancer at baseline (except non-melanoma skin) and with valid Food Frequency Questionnaire data and complete data on dietary caffeine. Regular coffee (none, 1, 2-3, 4-5, and ≥ 6 cups/day) and caffeine (tertiles) were assessed at baseline. Information on BCa risk factors was collected at baseline. The associations were examined using survival analysis, accounting for death as a competing risk.

RESULTS

The median follow-up time for our cohort was 18.3 years. During the follow-up, 5005 women developed invasive breast cancer. In multivariable analysis, coffee was not associated with the overall invasive BCa risk. Higher caffeine intake was mildly associated with increased BCa risk (2nd vs. 1st tertile SHR = 1.10, 95% CI 1.03-1.18, 3rd vs. 1st tertile SHR-1.05, 95% CI 0.98-1.13, overall p = 0.03). We found no interaction of coffee/caffeine with postmenopausal hormone use (p interaction = 0.44 and 0.42, respectively). In the exploratory analysis by ER/PR status, we found a positive association of caffeine with ER+ /PR+ BCa (2nd vs. 1st tertile SHR = 1.17, 95% CI 1.07-1.28, 3rd vs. 1st tertile SHR = 1.13, 95% CI 1.03-1.24, overall p = 0.002); no associations were observed for ER-/PR- tumors. Coffee was not associated with the risk of ER+ /PR+ or ER-/PR- tumors.

CONCLUSION

We found no associations of coffee with BCa risk, overall and for ER/PR-defined tumor subtypes. The higher caffeine consumption was mildly and positively associated with the overall BCa risk and with ER+ /PR+ tumors.

Caffeine intake from coffee and tea and invasive breast cancer incidence among postmenopausal women in the Women's Health Initiative

Research findings remain inconsistent whether caffeine consumption is associated with invasive breast cancer. We aimed to examine the association between caffeine intake from coffee and tea and incident invasive breast cancer among postmenopausal women. We included 79 871 participants in the Women's Health Initiative Observational Study in the current analysis. Incident invasive breast cancers were identified through September 30, 2015. Caffeine intake (mg/day) from caffeinated and decaffeinated coffee and tea was estimated based on self-reported frequency (cups/day) and average caffeine amount in each beverage. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Subgroup analyses were conducted to explore whether associations of caffeine intake from coffee and tea with invasive breast cancer were different by age, race and ethnicity, smoking status, body mass index, history of hormone therapy use, alcohol intake and subtypes of breast cancer. During a median follow-up of 16.0 years, 4719 incident invasive breast cancers were identified. No significant association was found between caffeine intake from coffee and tea and invasive breast cancer incidence after adjusting for demographic, lifestyle and reproductive factors: HRs (95% CIs) for increasing quartiles of caffeine intake compared to the lowest were 1.03 (0.94, 1.12), 1.04 (0.95, 1.13) and 1.03 (0.94, 1.13), respectively (P-for-trend = .54). No significant associations of coffee and tea intake (cups/day) with overall breast cancer risk were found. Our findings are consistent with others showing no clear association of caffeine consumption with invasive breast cancer among postmenopausal women.

Does coffee, tea and caffeine consumption reduce the risk of incident breast cancer? A systematic review and network meta-analysis

OBJECTIVE

We aimed to evaluate the association between coffee and/or tea consumption and breast cancer (BC) risk among premenopausal and postmenopausal women and to conduct a network meta-analysis.

DESIGN

Systematic review and network meta-analysis.

SETTING

We conducted a systematic review of electronic publications in the last 30 years to identify case-control studies or prospective cohort studies that evaluated the effects of coffee and tea intake.

RESULTS

Forty-five studies that included more than 3 323 288 participants were eligible for analysis. Network meta-analysis was performed to determine the effects of coffee and/or tea consumption on reducing BC risk in a dose-dependent manner and differences in coffee/tea type, menopause status, hormone receptor and the BMI in subgroup and meta-regression analyses. According to the first pairwise meta-analysis, low-dose coffee intake and high-dose tea intake may exhibit efficacy in preventing ER(estrogen receptor)- BC, particularly in postmenopausal women. Then, we performed another pairwise and network meta-analysis and determined that the recommended daily doses were 2-3 cups/d of coffee or ≥5 cups/d of tea, which contained a high concentration of caffeine, particularly in postmenopausal women.

CONCLUSIONS

Coffee and tea consumption is not associated with a reduction in the overall BC risk in postmenopausal women and is associated with a potentially lower risk of ER- BC. And the highest recommended dose is 2-3 cups of coffee/d or ≥5 cups of tea/d. They are potentially useful dietary protectants for preventing BC.

Benign breast disease and changes in mammographic breast density

Background

Mammographic breast density (MBD) and benign breast disease (BBD) are two of the strongest risk factors for breast cancer. Understanding trends in MBD by age and parity in women with BBD is essential to the clinical management and prevention of breast cancer.

Methods

Using data from the Early Determinants of Mammographic Density (EDMD) study, a prospective follow-up study of women born in 1959–1967, we evaluated MBD in 676 women. We used linear regression with generalized estimating equations to examine associations between self-reported BBD and MBD (percent density, dense area, and non-dense area), assessed through a computer-assisted method.

Results

A prior BBD diagnosis (median age at diagnosis 32 years) was reported by 18% of our cohort. The median time from BBD diagnosis to first available study mammogram was 9.4 years (range 1.1–27.6 years). Women with BBD had a 3.44% higher percent MBD (standard error (SE) = 1.56, p-value = 0.03) on their first available mammogram than women without BBD. Compared with parous women without BBD, nulliparous women with BBD and women with a BBD diagnosis prior to first birth had 7–8% higher percent MBD (β = 7.25, SE = 2.43, p-value< 0.01 and β = 7.84, SE = 2.98, p-value = 0.01, respectively), while there was no difference in MBD in women with a BBD diagnosis after the first birth (β = −0.22, SE = 2.40, p-value = 0.93).

Conclusion

Women with self-reported BBD had higher mammographic breast density than women without BBD; the association was limited to women with BBD diagnosed before their first birth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01426-7.

Coffee consumption and breast cancer risk: a narrative review in the general population and in different subtypes of breast cancer

PURPOSE

Most of the existing literature reports no association or a slight negative association between coffee consumption and the risk of developing breast cancer. However, the level of risk differs when considering various subgroups, such as menopausal status, hormonal status of the tumor or genetic mutations. The present review based on a literature search sets the point on the potential influence of a common daily drink, coffee, on the risk of developing breast cancer in the general population, in different subgroups of women and the consequences of drinking coffee after breast cancer has been diagnosed and treated.

RESULTS

This review confirms that in the general population, there is no association between coffee intake and breast cancer risk or a slight protective effect, even at high dosages. Coffee is inversely associated with breast cancer risk in postmenopausal women and in women carrying a BRCA1 mutation. Possible risk differences exist between slow and fast caffeine metabolizers and with weight. Coffee consumption after breast cancer diagnosis and surgery, associated with tamoxifen and/or radiotherapy, reduced the occurrence of early events. The effects of coffee intake are less clear in other subgroups, mainly premenopausal women, women carrying a BRCA2 mutation and tumors with variable hormonal status (positive or negative for ER/PR) and would need additional studies.

Logistic LASSO Regression for Dietary Intakes and Breast Cancer

A multitude of dietary factors from dietary fat to macro and micronutrients intakes have been associated with breast cancer, yet data are still equivocal. Therefore, utilizing data from the large, multi-year, cross-sectional National Health and Nutrition Examination Survey (NHANES), we applied a novel, modern statistical shrinkage technique, logistic least absolute shrinkage and selection operator (LASSO) regression, to examine the association between dietary intakes in women, ≥50 years, with self-reported breast cancer (n = 286) compared with women without self-reported breast cancer (1144) from the 1999–2010 NHANES cycle. Logistic LASSO regression was used to examine the relationship between twenty-nine variables, including dietary variables from food, as well as well-established/known breast cancer risk factors, and to subsequently identify the most relevant variables associated with self-reported breast cancer. We observed that as the penalty factor (λ) increased in the logistic LASSO regression, well-established breast cancer risk factors, including age (β = 0.83) and parity (β = −0.05) remained in the model. For dietary macro and micronutrient intakes, only vitamin B12 (β = 0.07) was positively associated with self-reported breast cancer. Caffeine (β = −0.01) and alcohol (β = 0.03) use also continued to remain in the model. These data suggest that a diet high in vitamin B12, as well as alcohol use may be associated with self-reported breast cancer. Nonetheless, additional prospective studies should apply more recent statistical techniques to dietary data and cancer outcomes to replicate and confirm the present findings.

Intake of Common Alcoholic and Non-Alcoholic Beverages and Breast Cancer Risk among Japanese Women: Findings from the Japan Collaborative Cohort Study

This study investigated the association between intake of common alcoholic and non-alcoholic beverages and breast cancer risk among Japanese women. This study included 33,396 Japanese women aged 40–79 years from 24 areas in Japan from the Collaborative Cohort study. During the follow-up period (≥20 years), 245 incidents or mortal breast cancers were documented. Multivariable logistic regression analysis was performed to assess the independent association between breast cancer risk and the intake of Japanese green tea, coffee, and alcohol. Japanese green tea was the most commonly consumed non-alcoholic beverage (81.6% of participants), followed by coffee (34.7%) and alcohol (23.6%). No significant associations were identified between the intake of green tea and coffee with breast cancer risk (odds ratio OR 1.15, 95% confidence interval [CI] 0.82–1.60, and OR 0.84, 95% CI 0.64–1.10, respectively). Alcohol intake was associated with significant breast cancer risk (OR 1.46, 95% CI 1.11–1.92), and even infrequent alcohol consumption (<1 times/week) was associated with substantially increased breast cancer risk (OR 2.07, 95% CI 1.39–3.09). Alcohol type, especially, wine and whisky intake tended to be marginally associated with breast cancer risk (OR 1.79, 95% CI 0.99–3.23 and [OR] 1.68, 95% CI 0.91–3.08, respectively). Alcohol consumption would be associated with increased breast cancer risk. However, intake of green tea or coffee does not appear to be associated with increased breast cancer risk.

Inter-Individual Variation in Cancer and Cardiometabolic Health Outcomes in Response to Coffee Consumption: A Critical Review

SCOPE

Coffee is associated with a lower risk of cancer, cardiovascular disease, and type 2 diabetes at the population level. However, individual susceptibility to the effects of coffee consumption will cause heterogeneity in health responses between individuals. In this critical review determinants of inter-individual variability in cancer and cardiometabolic health outcomes in response to coffee and caffeine consumption are systematically evaluated.

METHODS AND RESULTS

Embase and MEDLINE are searched for observational studies and clinical trials that examined variation in the response to coffee consumption. A total of 74 studies meet the inclusion criteria, which report variation in cancer (n = 24) and cardiometabolic health (n = 50) outcomes. The qualitative analysis shows that sex, BMI, smoking, alcohol intake, menopausal status, and genetic polymorphisms are probable or possible determinants of inter-individual variability in cancer and cardiometabolic health outcomes in response to coffee and caffeine consumption, albeit the majority of studies have insufficient statistical power to detect significant interaction between these factors and coffee consumption.

CONCLUSION

Several genetic and non-genetic determinants of inter-individual variability in the responses to coffee and caffeine consumption are identified, indicating that some of the health benefits of coffee may only occur in a subgroup of subjects.

Coffee consumption and breast cancer risk in the SUN project

INTRODUCTION

Breast cancer prevalence is growing worldwide. Many factors, such as diet and lifestyle could be determinants of the incidence of breast cancer. Coffee has been extensively studied in relation to several chronic diseases because of its multiple effects in health maintenance and its elevated consumption. We studied the relationship between coffee intake and breast cancer risk in the SUN (Seguimiento Universidad de Navarra) prospective cohort.

MATERIALS AND METHODS

We evaluated 10,812 middle-aged, Spanish female university graduates from the SUN Project, initially free of breast cancer. Coffee consumption was assessed with a 136-item validated food-frequency questionnaire (FFQ). Incident breast cancer cases were confirmed by a trained oncologist using medical records and by consultation of the National Death Index. We fitted Cox regression models to assess the relationship between baseline categories of coffee consumption and the incidence of breast cancer during follow-up. We stratified the analysis by menopausal status.

RESULTS

During 115,802 person-years of follow-up, 101 new cases of breast cancer were confirmed. Among postmenopausal women, more than 1 cup of coffee per day was associated with a lower incidence of breast cancer (HR 0.44; 95% confidence interval: 0.21, 0.92) in the fully adjusted model, compared to women who consumed one cup of coffee or less per day. We observed no significant differences in regard to premenopausal women.

CONCLUSION

Even though the number of cases was low, slight indications of an inverse association between coffee consumption and breast cancer risk among postmenopausal women were observed. Further longitudinal studies are warranted to confirm this finding.

Early-Life Growth and Benign Breast Disease

Using prospective data from the Early Determinants of Mammographic Density study (United States, 1959-2008, n = 1121), we examined the associations between maternal body size, birth size, and infant and early childhood growth during 3 time periods (0-4 months, 4-12 months, and 1-4 years) and benign breast disease (BBD) using multivariable logistic regression with generalized estimating equations. A total of 197 women (17.6%) reported receiving a diagnosis of BBD by a physician. Higher body mass index at age 7 years was inversely associated with BBD risk. Rapid weight gain from age 1 year to 4 years, defined as an increase of least 2 major percentiles (e.g., 5th, 10th, 25th, 50th, 75th, and 95th) relative to stable growth, defined as remaining within 2 percentiles, was also inversely associated with BBD (odds ratio (OR) = 0.51, 95% confidence interval (CI): 0.23, 1.15). In contrast, rapid weight gain in infancy was positively associated with BBD relative to stable growth (from 0 to 4 months, OR = 1.65, 95% CI: 1.04, 2.62; from 4 to 12 months, 1.85, 95% CI: 0.89, 3.85), independent of birth weight, which was not associated with BBD. Our results suggest that patterns of early-life weight gain are important to BBD risk. Thus, susceptibility to BBD, like susceptibility to breast cancer, might start in early life.

Associations of coffee, tea and caffeine intake with risk of breast, endometrial and ovarian cancer among Canadian women

BACKGROUND

Although, biologically plausible evidence has implicated coffee, tea and caffeine with carcinogenesis, there is a paucity of data on their associations with risk of cancer among Canadian women. Hence, we assessed their associations with risk of breast, endometrial and ovarian cancers within this population.

METHODS

The study comprised a subcohort of 3185 women from a cohort of 39,532 female participants who completed self-administered lifestyle and dietary questionnaires at enrollment. During a median follow-up of approximately 12.2years, we ascertained 922, 180 and 104 breast, endometrial and ovarian cancer cases, respectively. We used Cox proportional hazards regression models modified for the case-cohort design to estimate the hazard ratios (HR) and 95% confidence intervals (CI) for the associations of coffee, tea and caffeine with risk of selected cancers.

RESULTS

Coffee, tea, and caffeine intake were not associated with overall risk of breast and ovarian cancers. There was, however, a tendency towards an increased risk of breast cancer with increasing levels of total coffee, caffeinated coffee and/or caffeine among premenopausal and normal weight women. Total coffee, caffeinated coffee, and caffeine were inversely associated with risk of endometrial cancer (HR_{per cup increase}: 0.88; 95% CI: 0.79-0.95, HR_{per cup increase:} 0.88; 95% CI: 0.80-0.96 and HR_{per 100mg increase:} 0.93; 95% CI: 0.87-0.99, respectively).

CONCLUSION

Our findings suggest that coffee and/or caffeine may be associated with reduced risk of endometrial cancer but, probably, associated increased with risk of breast cancer among premenopausal or normal weight women. However, further studies are needed to confirm our findings.

Interactions of coffee consumption and postmenopausal hormone use in relation to breast cancer risk in UK Biobank

PURPOSE

We investigated the association of coffee consumption with postmenopausal breast cancer risk, overall and by the status of postmenopausal hormone therapy (PMH).

METHODS

This study included 126,182 postmenopausal women (2,636 with breast cancer and 123,546 without) from UK Biobank. Cancer diagnoses were ascertained through the linkage to the UK National Health Service Central Registers. Information on breast cancer risk factors and coffee consumption was collected at baseline and updated during follow-up. We used Cox proportional hazards regression to evaluate associations between coffee consumption and breast cancer, overall and in stratified analyses by woman's PMH status (none, past, current).

RESULTS

In the overall analysis, coffee consumption was not associated with breast cancer risk (Hazard Ratio [HR] 1.00, 95% CI 0.91-1.11 for 2-3 cups/day, and HR 0.98, 95% CI 0.87-1.10 for ≥ 4 cups/day, p-trend = 0.69). Women with no PMH history who consumed ≥ 4 cups/day had a 16% reduced risk of breast cancer as compared to women who consumed < 7 cups/week (HR 0.84, 95% CI 0.71-1.00). Among women with past PMH, those consuming ≥ 4 cups/day had a 22% greater risk of breast cancer than women consuming < 7 cups/week (HR 1.22, 95% CI 1.01-1.47). No association was found among current PMH users. We found no significant interaction between PMH and coffee consumption (p = 0.24).

CONCLUSIONS

Coffee consumption might be associated with increased breast cancer risk in women who used hormones in the past. Further studies are warranted to confirm these findings and elucidate potential biological mechanisms underlying the observed associations.

Coffee Intake Decreases Risk of Postmenopausal Breast Cancer: A Dose-Response Meta-Analysis on Prospective Cohort Studies

Aim: A dose-response meta-analysis was conducted in order to summarize the evidence from prospective cohort studies regarding the association between coffee intake and breast cancer risk. Methods: A systematic search was performed in electronic databases up to March 2017 to identify relevant studies; risk estimates were retrieved from the studies and linear and non-linear dose-response analysis modelled by restricted cubic splines was conducted. A stratified and subgroup analysis by menopausal and estrogen/progesterone receptor (ER/PR) status, smoking status and body mass index (BMI) were performed in order to detect potential confounders. Results: A total of 21 prospective studies were selected either for dose-response, the highest versus lowest category of consumption or subgroup analysis. The dose-response analysis of 13 prospective studies showed no significant association between coffee consumption and breast cancer risk in the non-linear model. However, an inverse relationship has been found when the analysis was restricted to post-menopausal women. Consumption of four cups of coffee per day was associated with a 10% reduction in postmenopausal cancer risk (relative risk, RR 0.90; 95% confidence interval, CI 0.82 to 0.99). Subgroup analyses showed consistent results for all potential confounding factors examined. Conclusions: Findings from this meta-analysis may support the hypothesis that coffee consumption is associated with decreased risk of postmenopausal breast cancer.

Coffee Intake Decreases Risk of Postmenopausal Breast Cancer: A Dose-Response Meta-Analysis on Prospective Cohort Studies

Aim: A dose-response meta-analysis was conducted in order to summarize the evidence from prospective cohort studies regarding the association between coffee intake and breast cancer risk. Methods: A systematic search was performed in electronic databases up to March 2017 to identify relevant studies; risk estimates were retrieved from the studies and linear and non-linear dose-response analysis modelled by restricted cubic splines was conducted. A stratified and subgroup analysis by menopausal and estrogen/progesterone receptor (ER/PR) status, smoking status and body mass index (BMI) were performed in order to detect potential confounders. Results: A total of 21 prospective studies were selected either for dose-response, the highest versus lowest category of consumption or subgroup analysis. The dose-response analysis of 13 prospective studies showed no significant association between coffee consumption and breast cancer risk in the non-linear model. However, an inverse relationship has been found when the analysis was restricted to post-menopausal women. Consumption of four cups of coffee per day was associated with a 10% reduction in postmenopausal cancer risk (relative risk, RR 0.90; 95% confidence interval, CI 0.82 to 0.99). Subgroup analyses showed consistent results for all potential confounding factors examined. Conclusions: Findings from this meta-analysis may support the hypothesis that coffee consumption is associated with decreased risk of postmenopausal breast cancer.

Coffee and cancer risk: A meta-analysis of prospective observational studies

Meta-analyses on coffee and cancer incidence mainly restricted to limited cancers. We carried out a more comprehensive meta-analysis of cohort studies to explore association between coffee and most cancer types. We conducted comprehensive search and summarized relative risk (RR) and 95% confidence intervals for the highest versus lowest coffee intake and cancer using STATA12. We conducted dose-analysis if result suggested significant association. The publication bias was evaluated with begg's and egger's test. Finally, 105 individual prospective studies were included. Inverse associations were observed on oral, pharyngeal, colon, liver, prostate, endometrial cancer and melanoma, with RR 0.69 (95% CI = 0.48-0.99, I² = 73.4%, P = 0.044), 0.87 (95% CI = 0.78-0.96, I² = 28.4%, P = 0.007), 0.46 (95% CI = 0.37-0.57, I² = 0%, P = 0), 0.89 (95% CI = 0.84-0.93, I² = 30.3%, P = 0.003), 0.73 (95% CI = 0.67-0.80, I²  = 0%, P = 0) and 0.89 (95% CI = 0.80-0.99, I²  = 0%, P = 0.031) respectively. However, the relative risk for lung cancer is 2.18 (95% CI = 1.26-3.75, I²  = 63.3%, P = 0.005). The summary relative risk for increment of 2 cups of coffee were RR = 0.73, 95% CI = 0.67-0.79 for liver cancer, RR = 0.97, 95% CI = 0.96-0.98 for prostate cancer and RR = 0.88, 95% CI = 0.85-0.92 for endometrial cancer. Accordingly, coffee intake was associated with reduced risk of oral, pharynx, liver, colon, prostate, endometrial cancer and melanoma and increased lung cancer risk.

Coffee, tea, caffeine intake, and the risk of cancer in the PLCO cohort

BACKGROUND

The association between coffee intake, tea intake and cancer has been extensively studied, but associations are not established for many cancers. Previous studies are not consistent on whether caffeine may be the source of possible associations between coffee and cancer risk.

METHODS

In the Prostate, Lung, Colorectal, and Ovarian cancer screening trial, of the 97,334 eligible individuals, 10,399 developed cancer. Cancers included were 145 head and neck, 99 oesophageal, 136 stomach, 1137 lung, 1703 breast, 257 endometrial, 162 ovarian, 3037 prostate, 318 kidney, 398 bladder, 103 gliomas, and 106 thyroid.

RESULTS

Mean coffee intake was higher in lower education groups, among current smokers, among heavier and longer duration smokers, and among heavier alcohol drinkers. Coffee intake was not associated with the risk of all cancers combined (RR=1.00, 95% confidence interval (CI)=0.96-1.05), whereas tea drinking was associated with a decreased risk of cancer overall (RR=0.95, 95% CI=0.94-0.96 for 1+ cups per day vs <1 cup per day). For endometrial cancer, a decreased risk was observed for coffee intake (RR=0.69, 95% CI=0,52-0.91 for ⩾2 cups per day). Caffeine intake was not associated with cancer risk in a dose-response manner.

CONCLUSIONS

We observed a decreased risk of endometrial cancer for coffee intake, and a decreased risk of cancer overall with tea intake.

Caffeine, coffee, and tea intake and urinary estrogens and estrogen metabolites in premenopausal women

BACKGROUND

Prior studies have found weak inverse associations between breast cancer and caffeine and coffee intake, possibly mediated through their effects on sex hormones.

METHODS

High-performance liquid chromatography/tandem mass spectrometry was used to quantify levels of 15 individual estrogens and estrogen metabolites (EM) among 587 premenopausal women in the Nurses' Health Study II with mid-luteal phase urine samples and caffeine, coffee, and/or tea intakes from self-reported food frequency questionnaires. Multivariate linear mixed models were used to estimate geometric means of individual EM, pathways, and ratios by intake categories, and P values for tests of linear trend.

RESULTS

Compared with women in the lowest quartile of caffeine consumption, those in the top quartile had higher urinary concentrations of 16α-hydroxyestrone (28% difference; Ptrend = 0.01) and 16-epiestriol (13% difference; Ptrend = 0.04), and a decreased parent estrogens/2-, 4-, 16-pathway ratio (Ptrend = 0.03). Coffee intake was associated with higher 2-catechols, including 2-hydroxyestradiol (57% difference, ≥4 cups/day vs. ≤6 cups/week; Ptrend = 0.001) and 2-hydroxyestrone (52% difference; Ptrend = 0.001), and several ratio measures. Decaffeinated coffee was not associated with 2-pathway metabolism, but women in the highest (vs. lowest) category of intake (≥2 cups/day vs. ≤1-3 cups/month) had significantly lower levels of two 16-pathway metabolites, estriol (25% difference; Ptrend = 0.01) and 17-epiestriol (48% difference; Ptrend = 0.0004). Tea intake was positively associated with 17-epiestriol (52% difference; Ptrend = 0.01).

CONCLUSION

Caffeine and coffee intake were both associated with profiles of estrogen metabolism in premenopausal women.

IMPACT

Consumption of caffeine and coffee may alter patterns of premenopausal estrogen metabolism.

Prospective study of breast cancer in relation to coffee, tea and caffeine in Sweden

Studies of coffee and tea consumption and caffeine intake as risk factors for breast cancer are inconclusive. We assessed coffee and tea consumption, caffeine intake, and possible confounding factors among 42,099 women from the Swedish Women's Lifestyle and Health study, the participants of which were aged 30-49 years at enrollment in 1991-1992. Complete follow-up for breast cancer incidence was performed through 2012 via linkage to national registries. Poisson regression models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer. During follow-up 1,395 breast cancers were diagnosed. The RR was 0.97 (95% CI 0.94-0.99) for a 1-unit increase in cups of coffee/day, 1.14 (95% CI 1.05-1.24) for a 1-unit increase in cups of tea/day, and 0.97 (95% CI 0.95-1.00) for a 100 mg/day increase in caffeine intake. Although the RR for no consumption (RR = 0.86, 95% CI 0.69-1.08), a group with a relatively small number of women, was not statistically significant, women with higher consumption had a decreased breast cancer risk (3-4 cups/day: RR = 0.87, 95% CI 0.76-1.00; ≥5 cups/day: RR = 0.81, 95% CI 0.70-0.94) compared to women consuming 1-2 cups of coffee/day. Compared to no consumption, women consuming >1 cups tea/day showed an increased breast cancer risk (RR = 1.19, 95% CI 1.00-1.42). Similar patterns of estimates were observed for breast cancer risk overall, during pre- and postmenopausal years, and for ER+ or PR+ breast cancer, but not for ER- and PR- breast cancer. Our findings suggest that coffee consumption and caffeine intake is negatively associated with the risk of overall and ER+/PR- breast cancer, and tea consumption is positively associated with the risk of overall and ER+/PR+ breast cancer.

Coffee and tea consumption and risk of pre- and postmenopausal breast cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study

INTRODUCTION

Specific coffee subtypes and tea may impact risk of pre- and post-menopausal breast cancer differently. We investigated the association between coffee (total, caffeinated, decaffeinated) and tea intake and risk of breast cancer.

METHODS

A total of 335,060 women participating in the European Prospective Investigation into Nutrition and Cancer (EPIC) Study, completed a dietary questionnaire from 1992 to 2000, and were followed-up until 2010 for incidence of breast cancer. Hazard ratios (HR) of breast cancer by country-specific, as well as cohort-wide categories of beverage intake were estimated.

RESULTS

During an average follow-up of 11 years, 1064 premenopausal, and 9134 postmenopausal breast cancers were diagnosed. Caffeinated coffee intake was associated with lower risk of postmenopausal breast cancer: adjusted HR=0.90, 95% confidence interval (CI): 0.82 to 0.98, for high versus low consumption; Ptrend=0.029. While there was no significant effect modification by hormone receptor status (P=0.711), linear trend for lower risk of breast cancer with increasing caffeinated coffee intake was clearest for estrogen and progesterone receptor negative (ER-PR-), postmenopausal breast cancer (P=0.008). For every 100 ml increase in caffeinated coffee intake, the risk of ER-PR- breast cancer was lower by 4% (adjusted HR: 0.96, 95% CI: 0.93 to 1.00). Non-consumers of decaffeinated coffee had lower risk of postmenopausal breast cancer (adjusted HR=0.89; 95% CI: 0.80 to 0.99) compared to low consumers, without evidence of dose-response relationship (Ptrend=0.128). Exclusive decaffeinated coffee consumption was not related to postmenopausal breast cancer risk, compared to any decaffeinated-low caffeinated intake (adjusted HR=0.97; 95% CI: 0.82 to 1.14), or to no intake of any coffee (HR: 0.96; 95%: 0.82 to 1.14). Caffeinated and decaffeinated coffee were not associated with premenopausal breast cancer. Tea intake was neither associated with pre- nor post-menopausal breast cancer.

CONCLUSIONS

Higher caffeinated coffee intake may be associated with lower risk of postmenopausal breast cancer. Decaffeinated coffee intake does not seem to be associated with breast cancer.

Lifestyle changes for prevention of breast cancer

Breast cancer is the second most common cause of death from cancer among women. Lifestyle changes are shown to be important in the prevention of breast cancer. Diet, physical activity, smoking, alcohol use, and vitamin and mineral use are key factors influencing the risk of breast cancer among women. Because these factors are related to each other, it is difficult to assess their individual roles in breast cancer. Some of these factors are alterable, meaning that women can decrease their risk for breast cancer by changing their behavior. Breast cancer is associated with a high rate of mortality and morbidity among women. Therefore, it is logical to try to find ways to decrease the risk of developing breast cancer. Lifestyle changes seem to be an easy, effective, and economical way to help prevention breast cancer. In women with a confirmed breast cancer diagnosis who are under radiotherapy treatment after undergoing a mastectomy, lifestyle changes are still very important. Some factors, such as smoking cessation and prevention of weight gain, may improve the long-term survival chances of these patients. Therefore, ways to increase women’s knowledge about the role of lifestyle changes in the prevention of breast cancer and in the survival of patients with diagnosed breast cancer should be considered and studied.

Tea consumption and the risk of five major cancers: a dose-response meta-analysis of prospective studies

Background

We conducted a dose–response meta-analysis of prospective studies to summarize evidence of the association between tea consumption and the risk of breast, colorectal, liver, prostate, and stomach cancer.

Methods

We searched PubMed and two other databases. Prospective studies that reported risk ratios (RRs) with 95% confidence intervals (CIs) of cancer risk for ≥3 categories of tea consumption were included. We estimated an overall RR with 95% CI for an increase of three cups/day of tea consumption, and, usingrestricted cubic splines, we examined a nonlinear association between tea consumption and cancer risk.

Results

Forty-one prospective studies, with a total of 3,027,702 participants and 49,103 cancer cases, were included. From the pooled overall RRs, no inverse association between tea consumption and risk of five major cancers was observed. However, subgroup analysis showed that increase in consumption of three cups of black tea per day was a significant risk factor for breast cancer (RR, 1.18; 95% CI, 1.05-1.32).

Conclusion

Ourresults did not show a protective role of tea in five major cancers. Additional large prospective cohort studies are needed to make a convincing case for associations.

Black tea, green tea and risk of breast cancer: an update

Previous meta-analysis indicated conflicting results in case–control versus cohort studies on the association of green tea with breast cancer risk, and conflicting results were also found in case–control versus cohort studies in another meta-analysis on the association of black tea with breast cancer risk. Many studies were published after the previous meta-analysis. Besides, the dose-response relationship of tea consumption with breast cancer risk is unclear. Thus the association of tea consumption with breast cancer risk was assessed incorporating new publications. Summary relative risk (RR) for highest versus lowest level of tea consumption was calculated based on fixed or random effect models. Dose-response relationship was assessed by restricted cubic spline model and multivariate random-effect meta-regression. The combined results from 9 studies suggested no significant association between green tea consumption and breast cancer risk (RR = 0.82, 95% CI = 0.64-1.04). No significant association was found among cohort studies and case-control studies after sensitivity analysis, respectively. A linear but not significant dose-response association was found between green tea consumption and breast cancer risk. The combined results from 25 studies demonstrated no significant association between black tea consumption and breast cancer risk (RR = 0.98, 95% CI = 0.93-1.03), and no significant association was found in subgroup analysis. A linear but not significant dose-response association was found between black tea consumption and breast cancer risk. Based on the current evidence, black tea and green tea might not contribute significantly to breast cancer risk, respectively.

Coffee and caffeine intake and breast cancer risk: an updated dose-response meta-analysis of 37 published studies

OBJECTIVE

We conducted an updated meta-analysis to summarize the evidence from published studies regarding the association of coffee and caffeine intake with breast cancer risk.

METHODS

Pertinent studies were identified by a search of PubMed and by reviewing the reference lists of retrieved articles. The fixed or random effect model was used based on heterogeneity test. The dose-response relationship was assessed by restricted cubic spline model and multivariate random-effect meta-regression.

RESULTS

37 published articles, involving 59,018 breast cancer cases and 966,263 participants, were included in the meta-analysis. No significant association was found between breast cancer risk and coffee (RR=0.97, P=0.09), decaffeinated coffee (RR=0.98, P=0.55) and caffeine (RR=0.99, P=0.73), respectively. And the association was still not significant when combining coffee and caffeine (coffee/caffeine) (RR=0.97, P=0.09). However, an inverse association of coffee/caffeine with breast cancer risk was found for postmenopausal women (RR=0.94, P=0.02), and a strong and significant association of coffee with breast cancer risk was found for BRCA1 mutation carriers (RR=0.69, P<0.01). A linear dose-response relationship was found for breast cancer risk with coffee and caffeine, and the risk of breast cancer decreased by 2% (P=0.05) for every 2 cups/day increment in coffee intake, and 1% (P=0.52) for every 200mg/day increment in caffeine intake, respectively.

CONCLUSIONS

Findings from this meta-analysis suggested that coffee/caffeine might be weakly associated with breast cancer risk for postmenopausal women, and the association for BRCA1 mutation carriers deserves further investigation.

Green tea intake is associated with urinary estrogen profiles in Japanese-American women

Scope

Intake of green tea may reduce the risk of breast cancer; polyphenols in this drink can influence enzymes that metabolize estrogens, known causal factors in breast cancer etiology.

Methods and results

We examined the associations of green tea intake (<1 time/week, 1-6 times weekly, or 7+ times weekly) with urinary estrogens and estrogen metabolites (jointly EM) in a cross-sectional sample of healthy Japanese American women, including 119 premenopausal women in luteal phase and 72 postmenopausal women. We fit robust regression models to each log-transformed EM concentration (picomoles per mg creatinine), adjusting for age and study center. In premenopausal women, intake of green tea was associated with lower luteal total EM (P trend = 0.01) and lower urinary 16-pathway EM (P trend = 0.01). In postmenopausal women, urinary estrone and estradiol were approximately 20% and 40% lower (P trend = 0.01 and 0.05, respectively) in women drinking green tea daily compared to those drinking <1 time/week. Adjustment for potential confounders (age at menarche, parity/age at first birth, body mass index, Asian birthplace, soy) did not change these associations.

Conclusions

Findings suggest that intake of green tea may modify estrogen metabolism or conjugation and in this way may influence breast cancer risk.

Coffee consumption and risk of breast cancer: an up-to-date meta-analysis

Objectives

This updated meta-analysis was conducted to assess the association between coffee consumption and breast cancer risk.

Methods

We conducted a systematic search updated July 2012 to identify observational studies providing quantitative estimates for breast cancer risk in relation to coffee consumption. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model, and generalized least square trend estimation was used to assess dose–response relationships.

Results

A total of 26 studies (16 cohort and 10 case–control studies) on coffee intake with 49497 breast cancer cases were included in the meta-analysis. The pooled RR showed a borderline significant influence of highest coffee consumption (RR = 0.96; 95% CI 0.93–1.00), low-to moderate coffee consumption (RR = 0.99; 95% CI 0.95–1.04), or an increment of 2 cups/day of coffee consumption (RR = 0.98; 95% CI 0.97–1.00) on the risk of breast cancer. In stratified analysis, a significant inverse association was observed in ER-negative subgroup. However, no significant association was noted in the others.

Conclusions

Our findings suggest that increased coffee intake is not associated with a significantly reduced risk of breast cancer, but we observe an inverse association in ER-negative subgroup analysis. More large studies are needed to determine subgroups to obtain more valuable data on coffee drinking and breast cancer risk.

Coffee and black tea consumption and breast cancer mortality in a cohort of Swedish women

Background:

Coffee and black tea contain a mixture of compounds that have the potential to influence breast cancer risk and survival. However, epidemiologic data on the relation between coffee and black tea consumption and breast cancer survival are sparse.

Methods:

We investigated the association between coffee and black tea consumption and survival among 3243 women with invasive breast cancer in the Swedish Mammography Cohort. Intake was estimated using a food frequency questionnaire. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs).

Results:

From 1987 to 2010 there were 394 breast cancer-specific deaths and 973 total deaths. Coffee and black tea were not associated with breast cancer-specific or overall mortality. Women consuming 4+ cups of coffee per day had a covariate and clinical characteristics-adjusted HR (95% CI) of death from breast cancer of 1.14 (0.71–1.83; p_trend=0.81) compared with those consuming <1 cup per day. Women consuming 2+ cups of black tea per day had a covariate and clinical characteristics-adjusted HR (95% CI) of death from breast cancer of 1.02 (0.67–1.55; p_trend=0.94) compared with non-tea drinkers. Caffeine was also not associated with breast cancer-specific (HR for top to bottom quartile=1.06; 95% CI=0.79–1.44; p_trend=0.71) or overall mortality.

Conclusion:

Our findings suggest that coffee, black tea, and caffeine consumption before breast cancer diagnosis do not influence breast cancer-specific and overall survival.

Coffee intake and breast cancer risk in the NIH-AARP diet and health study cohort

There are several biologic mechanisms whereby coffee might reduce breast cancer risk. Caffeine and caffeic acid, major coffee constituents, have been shown to suppress mammary tumor formation in animal models and to inhibit DNA methylation in human breast cancer cells, respectively. Coffee may also reduce risk through decreasing inflammation and influencing estrogen metabolism. However, epidemiologic studies have been inconsistent and few studies have examined the association by estrogen and progesterone receptor (ER/PR) status. We evaluated coffee intake for its effect on incident breast cancer in the National Institutes of Health-AARP Diet and Health Study cohort, which included 198,404 women aged 50-71 with no history of cancer, who in 1995-1996 completed a questionnaire capturing usual coffee intake over the past year. State cancer registry and mortality index linkage identified 9,915 primary incident breast carcinomas through December 2006; available information on hormone receptor (HR) status identified 2,051 ER+/PR+ and 453 ER-/PR- cancers. In multivariable proportional hazards models, coffee intake was not associated with breast cancer risk (p-value for trend = 0.38; relative risk = 0.98, 95% confidence interval: 0.91-1.07, for four or more cups per day as compared to women who never drank coffee), and results did not vary by body mass index or history of benign breast biopsy (p-value for interaction > 0.10). We found no evidence of a relationship with either caffeinated or decaffeinated coffee. Null findings persisted for risk of both HR-positive and -negative breast cancers. These findings from a large prospective cohort do not support a role of coffee intake in breast carcinogenesis.

Coffee and black tea consumption and risk of breast cancer by estrogen and progesterone receptor status in a Swedish cohort

BACKGROUND

Coffee and tea consumption has been inconsistently associated with the risk of breast cancer. We examined the associations of caffeinated coffee and black tea consumption with the incidence of breast cancer, overall and by estrogen receptor (ER) and progesterone receptor (PR) status of the tumor, in the Swedish Mammography Cohort.

METHODS

We prospectively followed up 61,433 women who were cancer free at baseline in 1987-1990. Coffee and tea consumption was assessed with a food-frequency questionnaire administered at baseline and in 1997. Incident invasive breast cancer cases were ascertained by linkage with Swedish Cancer registers.

RESULTS

Over a mean follow-up of 17.4 years, through December 2007, there were 2,952 incident cases of invasive breast cancer identified. Coffee consumption was not associated with risk of overall breast cancer (multivariate relative risk (RR) for ≥ 4 cups/day versus <1 cup/day = 1.02; 95% CI, 0.87-1.20) or with any subtype defined by ER and PR status. Black tea consumption was significantly positively associated with risk of overall breast cancer and ER+/PR+ tumors. The multivariate RRs comparing ≥ 2 cups/day of tea with no consumption were 1.22 (95% CI, 1.05-1.42) for overall breast cancer and 1.36 (95% CI, 1.09-1.69) for ER+/PR+ tumors.

CONCLUSION

Findings from this prospective study do not support a role of coffee consumption in the development of breast cancer but suggest that black tea consumption may be positively associated with risk of ER+/PR+ tumors.

Coffee consumption modifies risk of estrogen-receptor negative breast cancer

Introduction

Breast cancer is a complex disease and may be sub-divided into hormone-responsive (estrogen receptor (ER) positive) and non-hormone-responsive subtypes (ER-negative). Some evidence suggests that heterogeneity exists in the associations between coffee consumption and breast cancer risk, according to different estrogen receptor subtypes. We assessed the association between coffee consumption and postmenopausal breast cancer risk in a large population-based study (2,818 cases and 3,111 controls), overall, and stratified by ER tumour subtypes.

Methods

Odds ratios (OR) and corresponding 95% confidence intervals (CI) were estimated using the multivariate logistic regression models fitted to examine breast cancer risk in a stratified case-control analysis. Heterogeneity among ER subtypes was evaluated in a case-only analysis, by fitting binary logistic regression models, treating ER status as a dependent variable, with coffee consumption included as a covariate.

Results

In the Swedish study, coffee consumption was associated with a modest decrease in overall breast cancer risk in the age-adjusted model (OR_{> 5 cups/day} compared to OR_{≤ 1 cup/day}: 0.80, 95% CI: 0.64, 0.99, P trend = 0.028). In the stratified case-control analyses, a significant reduction in the risk of ER-negative breast cancer was observed in heavy coffee drinkers (OR_{> 5 cups/day} compared to OR_{≤ 1 cup/day} : 0.43, 95% CI: 0.25, 0.72, P trend = 0.0003) in a multivariate-adjusted model. The breast cancer risk reduction associated with higher coffee consumption was significantly higher for ER-negative compared to ER-positive tumours (P heterogeneity (age-adjusted) = 0.004).

Conclusions

A high daily intake of coffee was found to be associated with a statistically significant decrease in ER-negative breast cancer among postmenopausal women.

No association between coffee, tea or caffeine consumption and breast cancer risk in a prospective cohort study

OBJECTIVE

Numerous mechanisms for the effects of coffee, tea and caffeine on the risk of breast cancer have been suggested. Caffeine intake has already been associated with high plasma levels of female hormones, but associations have not been clearly demonstrated in epidemiological studies.

DESIGN

We examined prospectively the association of coffee, tea and caffeine consumption with breast cancer risk in a French cohort study.

SETTING

Dietary information was obtained from a 208-item diet history questionnaire self-administered in 1993-1995. Multivariable Cox proportional hazards regression models were used to estimate hazards ratios and 95 % confidence intervals.

SUBJECTS

The study was conducted on 67 703 women with available dietary information. During a median follow-up of 11 years, 2868 breast cancer cases were diagnosed.

RESULTS

Median intake was 280 ml/d (2·2 cups/d) for coffee and 214 ml/d (1·7 cups/d) for tea. Median caffeine intake was 164 mg/d. No association was found between consumption of coffee, tea or caffeine and breast cancer risk. Sub-analyses by tumour receptor status, menopausal status, type of coffee (regular or decaffeinated) and meals at which beverages were drunk led to the same conclusion.

CONCLUSIONS

Results from this prospective study showed no relationship between coffee, tea or caffeine intake and breast cancer risk overall or by hormone receptor status.

Tea and cancer prevention: epidemiological studies

Experimental studies have consistently shown the inhibitory activities of tea extracts on tumorigenesis in multiple model systems. Epidemiological studies, however, have produced inconclusive results in humans. A comprehensive review was conducted to assess the current knowledge on tea consumption and risk of cancers in humans. In general, consumption of black tea was not associated with lower risk of cancer. High intake of green tea was consistently associated with reduced risk of upper gastrointestinal tract cancers after sufficient control for confounders. Limited data support a protective effect of green tea on lung and hepatocellular carcinogenesis. Although observational studies do not support a beneficial role of tea intake on prostate cancer risk, phase II clinical trials have demonstrated an inhibitory effect of green tea extract against the progression of prostate pre-malignant lesions. Green tea may exert beneficial effects against mammary carcinogenesis in premenopausal women and recurrence of breast cancer. There is no sufficient evidence that supports a protective role of tea intake on the development of cancers of the colorectum, pancreas, urinary tract, glioma, lymphoma, and leukemia. Future prospective observational studies with biomarkers of exposure and phase III clinical trials are required to provide definitive evidence for the hypothesized beneficial effect of tea consumption on cancer formation in humans.

Methylxanthines and human health: epidemiological and experimental evidence

When considering methylxanthines and human health, it must be recognized that in many countries most caffeine is consumed as coffee. This is further confounded by the fact that coffee contains many bioactive substances in addition to caffeine; it is rich in phenols (quinides, chlorogenic acid, and lactones) and also has diterpenes (fatty acid esters), potassium, niacin, magnesium, and the vitamin B(3) precursor trigonelline. There is a paradox as consumption of either caffeine or caffeinated coffee results in a marked insulin resistance and yet habitual coffee consumption has repeatedly been reported to markedly reduce the risk for type 2 diabetes. There is strong evidence that caffeine reduces insulin sensitivity in skeletal muscle and this may be due to a combination of direct antagonism of A(1) receptors and indirectly β-adrenergic stimulation as a result of increased sympathetic activity. Caffeine may also induce reduced hepatic glucose output. With the exception of bone mineral, there is little evidence that caffeine impacts negatively on other health issues. Coffee does not increase the risk of cardiovascular diseases or cancers and there is some evidence suggesting a positive relationship for the former and for some cancers, particularly hepatic cancer.

Tea and coffee intake in relation to risk of breast cancer in the Black Women's Health Study

OBJECTIVE

Prospective studies of tea and coffee intake and breast cancer risk have yielded inconsistent results. None of these studies has reported separately on African-American women. We prospectively examined the relation of tea and coffee consumption to risk of breast cancer among 52,062 women aged 21-69 at enrollment in 1995 in the Black Women's Health Study.

METHODS

Dietary intake was assessed in 1995 and 2001 using a validated food frequency questionnaire. Cox proportional hazards models were used to estimate incidence rate ratios (IRR) and 95% confidence intervals (CI), adjusted for breast cancer risk factors.

RESULTS

During 12 years of follow-up through 2007, there were 1,268 incident cases of breast cancer. Intakes of tea, coffee, and caffeine were not significantly associated with the risk of breast cancer overall. The IRRs for consumption of ≥4 cups/day compared with none were 1.13 (95% CI 0.78-1.63) for tea and 1.03 (95% CI 0.77-1.39) for caffeinated coffee, and the IRR for the top quintile relative to the bottom quintile of caffeine intake was 1.04 (95% CI 0.87-1.24). Consumption of tea, coffee, and caffeine was not significantly associated with breast cancer risk according to menopausal status or hormone receptor status.

CONCLUSION

Our findings suggest that intakes of tea, coffee, and caffeine are not associated with the risk of breast cancer among African-American women.

Prevention of breast cancer (part I): epidemiology, risk factors, and risk assessment tools

Advances in breast cancer research have led to declining death rates from this disease because of early detection through mammographic screening and improved therapy for breast cancer. The concept that breast cancer, in some cases, can be prevented has been explored over the last three decades. This article, part I of a two-part series, will focus on the epidemiology, the risk factors associated with breast cancer, and the available risk assessment tools, which can help define who should be considered for risk reduction strategies. Part II will focus on discussing risk reduction strategies.

Caffeine's implications for women's health and survey of obstetrician-gynecologists' caffeine knowledge and assessment practices

OBJECTIVE

Caffeine has relevance for women's health and pregnancy, including significant associations with spontaneous abortion and low birth weight. According to scientific data, pregnant women and women of reproductive age should be advised to limit their caffeine consumption. This article reviews the implications of caffeine for women's psychological and physical health, and presents data on obstetrician-gynecologists' (ob-gyns) knowledge and practices pertaining to caffeine.

METHODS

Ob-gyns (N = 386) who are members of the American College of Obstetricians and Gynecologists' Collaborative Ambulatory Research Network responded to a 21-item survey about caffeine.

RESULTS

Although most knew that caffeine is passed through breast milk, only 24.8% were aware that caffeine metabolism significantly slows as pregnancy progresses. Many respondents were not aware of the caffeine content of commonly used products, such as espresso and Diet Coke, with 14.3% and 57.8% indicating amounts within an accurate range, respectively. Furthermore, ob-gyns did not take into account large differences in caffeine content across different caffeinated beverages with most recommending one to two servings of coffee or tea or soft drinks per day. There was substantial inconsistency in what was considered to be "high levels" of maternal caffeine consumption, with only 31.6% providing a response. When asked to indicate the risk that high levels of caffeine have on various pregnancy outcomes, responses were not consistent with scientific data. For example, respondents overestimated the relative risk of stillbirths and underestimated the relative risk of spontaneous abortion. There was great variability in assessment and advice practices pertaining to caffeine. More than half advise their pregnant patients to consume caffeine under certain circumstances, most commonly to alleviate headache and caffeine withdrawal.

CONCLUSIONS

The data suggest that ob-gyns could benefit from information about caffeine and its relevance to their clinical practice. The development of clinical practice guidelines for caffeine may prove to be useful.

Coffee and tea intake and risk of breast cancer

Known risk factors account for about 10-15% of breast cancer incidence suggesting that lifestyle exposures are crucial in its etiology. Previous epidemiological studies on the association between coffee and tea consumption and breast cancer risk have been inconsistent. We investigated the association of coffee and tea consumption with the risk of breast cancer among women in EPIC-NL cohort, a population-based prospective cohort in Netherlands with 27,323 participants. Exposure was measured by a validated food frequency questionnaire, and the outcome was verified by direct linkage with the Netherlands Cancer Registry. A total of 681 invasive primary breast cancers were diagnosed in 9.6 years of follow-up. Coffee intake increased the risk of breast cancer by more than twofold as compared to non-consumers (HR; 2.25, 95% CI; 1.30-3.90). This association did not hold after multivariate adjustment which resulted in a HR of 1.17, 95% CI; 0.65-2.12. After adjustment to breast cancer risk factors and lifestyle, no association was observed between intake of coffee or tea and risk of breast cancer across all categories of intake. These results were also not altered by body mass index (BMI). Coffee and tea consumption does not seem to be related to the risk of breast cancer in women.