Breast cancer and dietary factors in Taiwanese women

Dietary inflammatory patterns are associated with serum triglycerides and insulin in adults: A community-based study in Taiwan

BACKGROUND

Dietary patterns related to inflammation have become a focus of disease prevention but the patterns may vary among populations.

OBJECTIVE

The study was conducted to determine Taiwanese dietary inflammatory patterns and evaluate their associations with biomarkers of lipid and glucose METHODS: Data were taken from 5,664 community-dwelling individuals aged ≥55 years old recruited in 2009 - 2013 in the Healthy Aging Longitudinal Study in Taiwan (HALST). Dietary data were obtained from a food frequency questionnaire. An empirical dietary inflammatory pattern (EDIP) was derived from reduced rank regression models that explained the serum hsCRP, plasma IL-6, and TNFR1. Cross-sectional associations between dietary scores and biomarkers of total cholesterol (TC); high-density lipoprotein cholesterol (HDLC); low-density lipoprotein cholesterol, triglyceride (TG); and ratios of TG/HDLC, TG/TC, fasting glucose, insulin, and HbA1c were analyzed via multiple linear regression and adjusted for major confounders. The false discovery rate (FDR)-adjusted p <0.05 was considered statistically significant. Abdominal obesity was defined as a waist circumference of ≥90 cm for men and ≥80 cm for women.

RESULTS

Higher EDIP-HALST scores were associated with higher TG (per score increment: 1.62%, 95% CI: 0.58-2.76%; p_FDR=0.01), TG/HDLC (2.01%, 0.67-3.37%; p_FDR=0.01), and TG/TC (1.42%, 0.41-2.43%; p_FDR=0.01) and nonlinearly associated with insulin, with those in the middle tertile had the highest serum insulin concentrations (means: 5.12 μIU/mL, 4.78-5.78; p_FDR =0.04) in men, but not in women. No heterogeneity was detected between sexes. The associations with TG (1.23%, 0.19-2.23%; p_trend=0.02), TG/HDLC (1.62%, 0.30-2.96%; p_trend=0.02), and TG/TC (1.11%, 0.11-2.13%; p_trend=0.03) were stronger in participants with abdominal obesity, but were borderline associated in participants with normal abdominal circumferences (all p_trend=0.05).

CONCLUSIONS

Inflammatory diets, as measured via EDIP-HALST, were associated with serum TG concentration, particularly in participants with abdominal obesity. These findings may suggest that developing disease prevention strategies using dietary inflammatory patterns may be different by populations.

Association of food groups and dietary pattern with breast cancer risk: A systematic review and meta-analysis

BACKGROUND & AIMS

We conducted a systematic review and meta-analysis of current evidence for the association between food groups, dietary patterns, and breast cancer risk among the Asian population.

METHODS

This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We performed a systematic literature search up to December 2022 in English in the PubMed, Web of Science, Embase, and Cochrane databases. Risk ratios (RRs) with 95% confidence intervals (CIs) were extracted as effect sizes. Publication bias was estimated by two different funnel plot methods.

RESULTS

We collected the data from 15 cohort studies and 34 case-control studies meeting the search criteria. The meta-analysis found that the consumption of fruits and, likewise, vegetables were associated with a 29% lower risk of breast cancer, respectively [RR = 0.71 (0.55, 0.93); RR = 0.71 (0.53, 0.95)]. By contrast, no significance was found between meat, soy foods, and green tea consumption and breast cancer risk (P > 0.05). However, soy protein and isoflavone intake could lower breast cancer risk by 35% and 32%, respectively [RR = 0.65 (0.51, 0.83); RR = 0.68 (0.55, 0.82)]. As for the dietary pattern, high adherence to a healthy dietary pattern and, similarly, to a healthy eating index was associated with a 38% and 51% reduction in breast cancer risk, respectively [RR = 0.62 (0.44, 0.88; RR = 0.49 (0.27, 0.87)], while high adherence to an unhealthy dietary pattern was associated with a 44% increased risk [RR = 1.44 (1.06, 1.96)]. Considering alcohol consumption, a 75% increased risk of breast cancer was found [RR = 1.75 (1.33, 2.30)].

CONCLUSION

The present meta-analysis found that high intakes of fruits, vegetables, soy protein, and soy isoflavone significantly reduced the risk of breast cancer, while high intake of alcohol had a significantly increased risk. Meat, soy food, and green tea consumption were not significantly associated with breast cancer risk. Considering dietary patterns, high adherence to a healthy eating index and a healthy dietary pattern may reduce breast cancer risk. Conversely, adherence to unhealthy dietary patterns may increase breast cancer risk. However, further studies are needed to confirm the associations between dietary patterns and breast cancer in the Asian population.

Association between Allium vegetables and the risk of non-digestive tract cancer: A systematic review and meta-analysis of cohort and case-control studies

PURPOSE

To clarify the role of Allium vegetables in non-digestive tract cancer, we conducted this meta-analysis.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we conducted a meta-analysis of published studies assessing the associations between Allium vegetables and the risk of non-digestive tract cancer. We estimated the pooled odds ratio (OR) of non-digestive tract cancer for the highest and lowest Allium vegetable consumption using random-effects models. A dose-response regression model was used to evaluate the relationship between Allium vegetables and non-digestive tract cancer risk.

RESULTS

In a pooled analysis of 25 studies (11 cohort and 14 case-control studies) on Allium vegetables, a total of 18,070 patients with non-digestive tract cancer were finally included. Integrated OR of non-digestive tract cancer was 0.86 [95% confidence interval (CI):0.80-0.93] for the highest versus the lowest Allium vegetable consumption for all studies, 0.78 (95% CI:0.69-0.90) for case-control studies and 0.94 (95%CI: 0.87-1.02) for cohort studies. Sensitivity analysis showed that the pooled effect was stable. No apparent publication bias was identified in this study; however, the cumulative meta-analysis suggested that studies conducted earlier (from 1994 to 1997) might be a source of heterogeneity. Dose-response regression model indicated that Allium vegetable consumption was associated with the risk of non-digestive tract cancer (P = 0.001 for non-linearity; P = 0.032 for linearity).

CONCLUSION

Higher Allium vegetable consumption could reduce the risk of non-digestive tract cancers, demonstrating the protective role of Allium vegetables.

Hot and Cold Theory: Evidence in Nutrition

Ancient scholars across cultures have postulated that by being less potent versions of herbs, food plays a substantive role in the maintenance of health and treatment of disease. A commonality among these traditional medical systems is in relation to the 'heating' and 'cooling' properties of foods. In this chapter, 'hot' and 'cold' classifications of foods are explored, along with ways to optimize health and combat disease. Scientific evaluations of 'hot' and 'cold' properties are also reviewed in relation to chemical compositions and physiological impacts. A broad scoping Google Scholar search was conducted to identify relevant articles. Scientific evaluations were heterogeneous and of mixed quality. Nonetheless some evidence supported the traditional 'hot' and 'cold' classifications. Overall, 'heating' foods were associated with metabolism and sympathetic nervous system enhancement via increased proportions of caffeine, carbohydrate, protein, fat, and calories; as well as greater oxidation potential; vasodilatory and pro-inflammatory effects; and higher acidity and aromatic compound content. 'Cooling' foods were contrastly found to be higher in water, fiber, alkalinity, and aliphatic compounds; as well as associated with anti-inflammatory, and detoxification (elimination) processes. With the potential to specifically tailor diets to suit individual needs, further high-quality research to substantiate traditional food classifications is warranted.

Increased risk of second primary malignancies among endometrial cancer survivors receiving surgery alone: A population-based analysis

Background

Women with endometrial cancer (EC) have favorable prognoses, leaving them vulnerable to the development of second primary cancers (SPCs). We investigated the SPC risk and survival outcomes among EC patients treated with surgery alone in order to exclude the impact of adjuvant treatment on the results.

Methods

Data from the Taiwan Cancer Registry from 1995 to 2013 were analyzed. Standardized incidence ratios (SIRs) of SPCs among EC survivors were calculated.

Results

Among 7725 women enrolled, 478 developed an SPC. The overall SIR for SPCs in EC survivors was 2.84 (95% confidence interval [CI] 2.59–3.10) compared with the general female population. Women diagnosed with EC at age <50 years had a higher SIR for an SPC than those diagnosed at age ≥50 years (SIR = 4.38 vs. 1.28). The most frequent site of an SPC was the small intestine (SIR = 8.39, 95% CI 2.72–19.58), followed by the kidney (SIR = 4.84, 95% CI 1.78–10.54), and oral cavity (SIR = 4.52, 95% CI 2.17–8.31). Women, regardless of age at EC diagnosis, had significantly higher SIRs for subsequent breast, colorectal, lung, and thyroid cancer, and lymphoma. Women with an SPC had shorter overall survival than those without (5‐year: 88.9 vs. 94.2%, 10‐year: 71.3 vs. 89.8%, 15‐year: 62.3 vs. 86.1%, and 20‐year: 47.6 vs. 81.1%, all ps<0.001).

Conclusions

Even women treated for EC with surgery alone, especially young EC survivors, had an increased risk of SPCs. Genetic counseling/testing is recommended for young EC patients, and all are recommended to receive regular surveillance and screening for breast, colorectal, and lung cancers.

Endocrine disrupting chemicals and breast cancer: a systematic review of epidemiological studies

BACKGROUND

Endocrine-disrupting compounds (EDCs) are ubiquitous substances that are found in our everyday lives, including pesticides, plasticizers, pharmaceutical agents, personal care products, and also in food products and food packaging. Increasing epidemiological evidence suggest that EDCs may affect the development or progression of breast cancer and consequently lead to lifelong harmful health consequences, especially when exposure occurs during early life in humans. Yet so far no appraisal of the available evidence has been conducted on this topic.

OBJECTIVE

To systematically review all the available epidemiological studies about the association of the levels of environmental exposures of EDCs with breast cancer risk.

METHODS

The search was performed in accordance with the PRISMA guidelines. We retrieved articles from PubMed (MEDLINE) until 10 March 2021. The key words used in this research were: "Endocrine disruptor(s)" OR "Endocrine disrupting chemical(s)" OR any of the EDCs mentioned below AND "Breast cancer" to locate all relevant articles published. We included only cohort studies and case-control studies. All relevant articles were accessed in full text and were evaluated and summarized in tables.

RESULTS

We identified 131 studies that met the search criteria and were included in this systematic review. EDCs reviewed herein included pesticides (e.g. p,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethylene (DDE), atrazine, 2,3,7,8-tetrachloridibenzo-p-dioxin (TCDD or dioxin)), synthetic chemicals (e.g. bisphenol A (BPA), phthalates, per- and polyfluoroalkyl substances (PFAS), parabens, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), contraceptive pills), phytoestrogens (e.g. genistein, resveratrol), and certain mycotoxins (e.g. zearalenone). Most studies assessed environmental EDCs exposure via biomarker measurements.

CONCLUSION

We identified certain EDC exposures could potentially elevate the risk of breast cancer. As majority of EDCs are highly persistent in the environment and bio-accumulative, it is essential to assess the long-term impacts of EDC exposures, especially multi-generational and transgenerational. Also, since food is often a major route of exposure to EDCs, well-designed exposure assessments of potential EDCs in food and food packing are necessary and their potential link to breast cancer development need to be carefully evaluated for subsequent EDC policy making and regulations.

Higher dietary soy intake appears inversely related to breast cancer risk independent of estrogen receptor breast cancer phenotypes

The relationship between soy intake (SI) and breast cancer (BC) has been widely investigated with limited information on the significance of hormone receptor status of BC on the association. This study assessed the relationship between SI and BC risk in the context of oestrogen receptor (ER) status of BC. We meta-analyzed data from published studies on SI and BC after a methodical search of EMBASE, PubMed and Cochrane Library through December 2019. Summary estimates with 95% confidence intervals (CI) were presented using a random-effects model. Eighteen (5 cohorts and 13 case-control) studies, were included in this meta-analysis and SI was inversely associated with BC risk [OR (95%) for highest vs. lowest soy food intake = 0.88 (0.84-0.92), P < 0.001, I ² = 76.1%, Egger's p-value = 0.425] among all women. The inverse relationship was stronger among premenopausal women [OR (95%) = 0.79 (0.71-0.87), P < 0.001, I ² = 77.3%, Egger's p-value = 0.644]. In addition, SI was inversely associated with BC risk among ER-negative (-) BC women [OR (95%) = 0.71 (0.57-0.90), P = 0.013, I ² = 72.0%, Egger's p-value = 0.355] and among ER-positive (+) BC women [OR (95%) = 0.87 (0.79-0.96), P = 0.008 I ² = 74.6%, Egger's p-value = 0.061]. SI appears inversely associated with BC risk, with a stronger inverse association among pre-menopausal and ER-negative BC women.

Total Dietary Fats, Fatty Acids, and Omega-3/Omega-6 Ratio as Risk Factors of Breast Cancer in the Polish Population - a Case-Control Study

BACKGROUND/AIM

Breast cancer is the most common type of cancer among women around the world and the leading cause of cancer-related death among women. The knowledge about modifiable risk factors, such as diet, can be an acceptable, cheap and non-pharmacological prevention tool. The aim of this study was to investigate the association between dietary fat, dietary fatty acids, fish intake, and breast cancer in women.

PATIENTS AND METHODS

A case-control study was designed. A total of 201 consecutive, newly diagnosed, polish female cancer patients (mean age: 58 years) and 201 one-to-one age-matched controls were enrolled. A standardised questionnaire assessing various socio-demographic, clinical, lifestyle, and dietary characteristics was applied via face-to-face interviews. Detailed dietary intake information was assessed using a validated Food Frequency Questionnaire. Odds ratios (OR) and 95% confidence intervals (95%CI) were obtained using multiple unconditional logistic regression models controlling for non-dietary and dietary potential confounders.

RESULTS

Consumption of polyunsaturated fats (PUFA) over 10% of total energy intake was associated with a significantly lower risk of breast cancer compared to low intake of PUFA (OR=0.4, 95%CI=0.19-0.85). Low (<0.2) omega-3/ omega-6 ratio (OR=2.04, 95%CI=0.996-4.17), fish consumption less than once every six months (OR=3.37, 95%CI=1.57-7.23) and being overweight (OR=2.07, 95%CI=1.3-3.3) were associated with increased risk of breast cancer. Residents of rural areas had a significantly higher risk compared to women from urban areas (OR=1.8, 95%CI=1.06-3.03).

CONCLUSION

High intake of PUFA can decrease the risk of breast cancer, while the low omega-3/omega-6 ratio increases the risk. In addition, overweight state, eliminating fish from the diet and living in rural areas can also increase the risk of breast cancer.

Onion and Garlic Intake and Breast Cancer, a Case-Control Study in Puerto Rico

Studies show an inverse association between onion and garlic intake and risk of cancers of the lung, prostate, and stomach. There is limited evidence on the association between onion and garlic intake and breast cancer. We assessed this association in a population-based, case-control study in Puerto Rico. Incident, primary breast cancer cases (n = 314) were identified among women aged 30-79 from hospital and clinic records. Controls (n = 346) were women with no history of cancer other than nonmelanoma skin cancer, residents of the same area. Dietary intake was estimated using a food frequency questionnaire. Total onion and garlic intake included sofrito (a popular garlic- and onion-based condiment) intake frequency. Unconditional logistic regression assessed the association between onion and garlic consumption and breast cancer adjusting for age, education, parity, family history, body mass index, age at menarche, total energy, and smoking. Inverse associations with breast cancer were observed for moderate (OR (odds ratio) = 0.59, 95% CI (confidence interval): 0.35, 1.01) and high consumption (OR = 0.51, 95% CI: 0.30, 0.87) compared to low consumption of onion and garlic (P_trend = 0.02). Results were similar when stratified by menopausal status. Study results suggest that high onion and garlic consumption is protective against breast cancer in this population.

The association between green tea consumption and breast cancer risk: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to critically evaluate the relation between green tea (GT) consumption and the risk of breast cancer. Popular electronic databases were systematically searched for papers in English language. All case-control and cohort studies in addition to randomized clinical trials were included if they assessed the chemopreventive effects of GT on breast cancer. The quality of included studies was assessed using the Newcastle-Ottawa and Jadad scale. This systematic review comprised 14 studies: 9 case-control studies, 4 cohort studies, and 1 clinical trial. Odds ratio (OR) in case-control studies suggested that women in the group receiving the highest level of GT had 19% reduction in breast cancer risk compared with those who received the lowest level of GT (summary OR = 0.81, p = .031; 95% CI [0.66, 0.981]; heterogeneity, I²  = 71.53, p < .001, random effect model; 9 studies). OR in cohort studies also showed no significant difference (OR = 0.99, p = .94; 95% CI [0.81, 1.138]; heterogeneity, I²  = 19.06, p = .29; fixed-effect model; 4 studies). According to the only clinical trial, treatment with GT could not alter the mammographic density compared with placebo (26% vs. 25%). It cannot be concluded that GT consumption may decrease the risk of breast cancer. Due to high heterogeneity, a pooled analysis of case-control and cohort studies was not performed.

Is vegetarian diet associated with a lower risk of breast cancer in Taiwanese women?

Background

Studies on the relationship between vegetarian diet and breast cancer in Asian populations are limited. This study aimed to investigate the relationship between vegetarian diet, dietary patterns, and breast cancer in Taiwanese women.

Methods

This case-control study compared the dietary patterns of 233 breast cancer patients and 236 age-matched controls. A questionnaire about vegetarian diets and 28 frequently-consumed food items was administered to these 469 patients in the surgical department of Taipei Tzu Chi Hospital. Serum biochemical status was also examined.

Results

There were no significant differences between the two groups for age, education, family history, oral contraceptive usage, or regular exercise. However, the cancer group presented with both a higher body mass index and an older age of primiparity (P < 0.05). Two food items (shellfish and seafood) were highly correlated (correlation coefficient = 0.77), so shellfish was excluded to avoid multicollinearity. A factor analysis of 27 food items produced five dietary patterns: meat, processed meat, fruit/vegetable/soybean, dessert/sugar, and fermented food. Multivariate logistic regression showed that meat/fat and processed meat dietary patterns were associated with breast cancer risk (odds ratio (OR): 2.22, 95% CI 1.67–2.94, P < 0.001; OR: 1.49, 95% CI 1.09–2.04, P = 0.013, respectively). Vegetarian diet, high isoflavone intake, and high albumin levels were inversely associated with breast cancer risk (P < 0.05). Vegetarians had a higher daily soy isoflavone intake than non-vegetarians (25.9 ± 25.6 mg vs. 18.1 ± 15.6 mg, P < 0.001).

Conclusions

Vegetarian diets show as protective role against breast cancer risk, while meat and processed meat dietary patterns are associated with a higher breast cancer risk.

Electronic supplementary material

The online version of this article (10.1186/s12889-017-4819-1) contains supplementary material, which is available to authorized users.

Incidence and lifetime risk of uterine corpus cancer in Taiwanese women from 1991 to 2010

OBJECTIVE

Although uterine corpus cancer has been the most common malignancy of the female genital tract in many countries, the lifetime risk of this cancer has not yet been determined among Taiwanese women. The purpose of the study was to describe the change in incidence and the lifetime risk of uterine corpus cancer over a 20-year period from 1991 to 2010 in Taiwan.

MATERIALS AND METHODS

We conducted a population-based registry study using the released database (available online) from the Taiwan Cancer Registry.

RESULTS

A total of 15,542 women newly diagnosed with uterine corpus cancer were included in this study. The total number of this cancer increased by 5.7-fold from 1991 to 2010. The annual age-specific rate nearly doubled during the past decade (2001-2010) when compared with the previous decade (1991-2000). Incidence rates were highest in women aged 50-59 years, and increasing incidence rates were observed in each age strata starting from 40 years to 85 years and more, after the year 2000. The lifetime risk of being diagnosed with uterine corpus cancer was 0.39% in 1991-1995, 0.54% in 1996-2000, 0.73% in 2001-2005, and 1.12% in 2006-2010 among Taiwanese women.

CONCLUSION

According to the observed changes in incidence rate, the burden of uterine corpus cancer in the general female population is expected to increase in the near future. From a public-health perspective, care providers should develop strategies for the prevention, early detection, and intervention to reduce the rapidly increasing incidence of uterine corpus cancer in Taiwan.

Circulating 25-hydroxyvitamin D and physical performance in older adults: a nationwide study in Taiwan

BACKGROUND

A previous study indicated that 31% of the elderly in Taiwan have a vitamin D deficiency. Vitamin D adequacy has been associated with physical performance in the elderly.

OBJECTIVES

The first aim of the current study was to identify the determinants for vitamin D deficiency. The second aim was to evaluate the association between vitamin D status and physical performance.

DESIGN

A total of 5664 community-dwelling participants aged ≥55 y were recruited since 2008. Plasma total 25-hydroxyvitamin D concentrations were originally determined by ELISA and calibrated to a chemiluminescence measurement. Physical performance was assessed by handgrip strength, the Short Physical Performance Battery, timed up and go, a 6-min walk test, and single-leg stands. Multiple linear regression and logistic regression were used to estimate the cross-sectional associations.

RESULTS

Vitamin D inadequacy (<50 nmol/L) was related to higher education (P-trend < 0.01), body mass index [(BMI; in kg/m²) ORs (95% CIs) for ≥30 compared with 18.5 to <25 were 1.78 (1.14, 2.78) for men and 1.53 (1.11, 2.11) for women], and vegetable intake [fourth compared with first quartile, 1.58 (1.15, 2.18) for men and 2.38 (1.82, 3.12) for women]. Higher intakes of fish [fourth compared with first quartile, 0.44 (0.33, 0.59) for men and 0.27 (0.21, 0.36) for women] and milk [fourth compared with first quartile, 0.46 (0.31, 0.69) for men and 0.69 (0.49, 0.95) for women] were associated with lower risk of vitamin D inadequacy. Few subjects had 25-hydroxyvitamin D concentrations <30 nmol/L. Above that concentration, there was no dose-effect relation with physical performance except for single-leg stands.

CONCLUSIONS

The factors associated with vitamin D inadequacy in Taiwan were higher education, higher BMI, and lower fish and milk intakes. No dose-effect relation existed between vitamin D concentration and physical performance except for single-leg stands. This study was registered at www.clinicaltrials.gov as NCT02677831.

Meta-Analysis of Saturated Fatty Acid Intake and Breast Cancer Risk

The associations between saturated fatty acid (SFA) consumption and risk of breast cancer (BC) remains inconclusive. Therefore, we conducted this meta-analysis to determine the quantitative relations between dietary SFA intake and incidence of BC.Literatures published up to April 2015 were systematically screened through Pubmed and Web of Science. Relevant publication quality was evaluated by conducting the Newcastle-Ottawa scale. We used fixed effects models or random effect models to calculate the summary relative risks (RRs) and odds ratios (ORs), and conducted sensitivity analyses and evaluated the publication bias.We identified a total of 52 studies (24 cohort studies and 28 case-control studies), with over 50,000 females diagnosed with BC. The associations between dietary SFA intake and risk of BC were 1.18 for case-control studies (high vs low intake, 95% confidence interval [CI] = 1.03-1.34) and 1.04 for cohort studies (95% CI = 0.97-1.11). When restricted analyses to population-based studies, positive associations were observed for both cohort (RR [95% CI] = 1.11 [1.01-1.21]) and case-control studies (OR [95% CI] = 1.26 [1.03-1.53]). Additionally, for case-control studies, significant positive associations between higher SFA intake and BC risk were observed for Asian (OR [95% CI] = 1.17 [1.02-1.34]) and Caucasian (OR [95% CI] = 1.19 [1.00-1.41]), as well as for postmenopausal women (OR = 1.33, 95% CI: 1.02-1.73). In contrast, higher dietary SFA intake was not associated with risk of BC among premenopausal women, in cohort studies or hospital-based studies.A positive association between higher dietary SFA intake and postmenopausal BC risk was observed in case-control but not in cohort studies. More studies are warranted to confirm these findings.

Brassiere wearing and breast cancer risk: A systematic review and meta-analysis

AIM: To evaluate existing evidence for the association between different type of brassiere exposures and the risk of breast cancer.

METHODS: Ovid Medline, CINAHL, Cochrane Data Base of Systematic Reviews, Pubmed, Scopus, Proquest, Sciencedirect, Wiley Online Library, WanFang Data, Hong Kong Index to Chinese Periodicals, China Journal Net, Chinese Medical Current Contents, Chinese Biomedical Literature Database, China Academic Journals Full-Text database, Taiwan Electronic Periodical Services and HyRead; reference lists of published studies; original research studies published in English or Chinese examining the association between type and duration of brassiere-wearing and breast cancer risk. Data were abstracted by a first reviewer and verified by a second. Study quality was rated according to predefined criteria. “Fair” or “good” quality studies were included. Results were summarised by meta-analysis whenever adequate material was available.

RESULTS: Twelve case-control studies were included in the review. Meta-analysis showed brassiere wearing during sleep was associated with a two times of increased odds.

CONCLUSION: The present review demonstrates insufficient evidence to establish a positive association between the duration and type of brassiere wearing and breast cancer. Further research is essential; specifically, a large-scale epidemiological study of a better design is needed to examine the association between various forms of brassiere exposure in detail and breast cancer risk, with adequate control of confounding variables.

Discovery of 3-phenylquinolinylchalcone derivatives as potent and selective anticancer agents against breast cancers

A number of 3-phenylquinolinylchalcone derivatives were synthesized and evaluated in vitro for their antiproliferative activities against three breast cancer cell lines (MCF-7, MDA-MB-231, and SKBR-3), and a non-cancer normal epithelial cell line (H184B5F5/M10). Among them, (E)-3-[3-(4-methoxyphenyl)quinolin-2-yl]-1-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (7) was active against the growth of MCF-7, MDA-MB-231, and SKBR-3 with IC50 values of 1.05, 0.75, and 0.78 μM respectively without significant cytotoxicity to the normal H184B5F5/M10 cell line and therefore, was selected as a new lead for further mechanism studies. Results indicated that compound 7 inhibited the polymerization of tubulins, induced G2/M cell cycle arrest via modulation of the cyclin B1, cdk1 and CDC25. Compound 7 ultimately induced cell apoptosis by the increase of apoptotic protein Bax and the decrease of anti-apoptotic protein Bcl-2. In addition, PARP was cleaved while caspase-3 and -8 activities were induced after the treatment of compound 7 for 24 h in a concentration-dependent manner. Thus, compound 7 induces cell cycle arrest at G2/M phase via cleavage of PARP, induces caspase-3 and -8 activities and consequently to cause the cell death. Further study on the structure optimization of 7 is ongoing.

Association between dietary factors and breast cancer risk among Chinese females: systematic review and meta-analysis

BACKGROUND

Evidence for associations between dietary factors and breast cancer risk is inconclusive among Chinese females. To evaluate this question, we conducted a systematic review of relevant case-control and cohort studies.

METHODS

Studies were systematically searched among 5 English databases (PudMed, ScienceDirect, Wiley, Clinicaltrials.gov, and Cochrane) and 3 Chinese databases (CNKI, WanFang, and VIP) until November 2012. Random effects models were used to estimate summary odds ratios (ORs) and the corresponding 95% confidence intervals (CIs).

RESULTS

Thirty one case-control studies and two cohort studies involving 9,299 cases and 11,413 controls were included. Consumption of both soy and fruit was significantly associated with decreased risk of breast cancer, with summary ORs of 0.65 (95% CIs: 0.43-0.99; I2=88.9%, P<0.001; N=13) and 0.66 (95% CIs: 0.47-0.91; I2=76.7%, P<0.001; N=7), respectively. Consumption of fat was significantly associated with increased risk of breast cancer (OR=1.36; 95% CIs: 1.13-1.63; I2=47.9%, P=0.088; N=6). There was non- significant association between consumption of vegetables and breast cancer risk (OR=0.72; 95% CIs: 0.51-1.02; I2= 74.4%, P<0.001; N=9). However, sensitivity analysis based on adjusted ORs showed decreased risk of breast cancer was also associated with consumption of vegetables (OR=0.49; 95% CIs: 0.30-0.67).

CONCLUSION

Both soy food and fruit are significantly associated with decreased risk of breast cancer among Chinese females, and vegetables also seems to be protective while dietary fatexerts a promoting influence.

Adjuvant tamoxifen influences the lipid profile in breast cancer patients

BACKGROUND

Currently there is a debate regarding whether tamoxifen used in breast cancer has an impact on lipid profiles. The aim of this study was to determine whether tamoxifen has an impact on the serum lipid profile in Taiwanese women.

PATIENTS AND METHODS

Data of 109 patients were collected from the routine clinical follow-up for women with hormone receptor-positive breast cancer who were treated between July 2005 and March 2008. These patients were divided into 2 subgroups, based on their tumor grade and lymph node status. Subgroup 1 patients had tumor grade I/II and a negative lymph node status. Those patients with tumor grade III or a positive lymph node status were defined as subgroup 2.

RESULTS

In the 109 patients, the mean serum total cholesterol (TC) levels after tamoxifen treatment, as well as the serum low-density lipoprotein cholesterol (LDL-C) levels, were lower than the baseline levels, with statistically significant differences. Treatment with tamoxifen lowered the serum TC and LDL-C levels in both subgroups.

CONCLUSIONS

The results indicate that tamoxifen has an impact on the serum lipid profile of breast cancer patients in Taiwan. Physicians should follow up the lipid profile in these patients.

General supplement use, subsequent use and cancer risk in the UK Women's Cohort Study

BACKGROUND/OBJECTIVES

To determine whether general dietary supplement use is associated with cancer risk in UK women and to estimate risks related to use at one and two recording points.

SUBJECTS/METHODS

Cox's proportional hazard regression models were used to estimate cancer risks for 32 665 middle-aged women in the UK Women's Cohort Study relating to any current supplement use recorded in a baseline questionnaire. During a median follow-up of 15 years, there were 3936 registered cancer incidences, including 1344 breast, 429 smoking-related and 362 colorectal cancers. Cancer risks for 12 948 of these women, who also completed questionnaires on average 4.4 years later, were estimated in relation to any supplement use at both time points (1527 cancers, including 561 breast, 131 smoking-related and 141 colorectal cancers). Adjustments were made for baseline confounders.

RESULTS

Total smoking-related cancers were associated with baseline supplement use (hazard ratio (HR)=1.41, 95% confidence interval (CI): 1.10, 1.81) compared with non-use, but not associated with use at both recording points (HR=1.29; 95% CI: 0.78, 2.13) compared with use at neither. There was no evidence of the associations between total, colorectal or breast cancers and baseline supplement use, or use at both recording points. In sub-analyses, no significant associations with breast cancer were found for premenopausal or postmenopausal baseline users, or similarly for use at both points (HR=1.35, 95% CI: 0.91, 2.01; and HR=0.93, 95% CI: 0.68, 1.26, respectively).

CONCLUSIONS

There was evidence that general supplement use was associated with increased smoking-related cancer risk, but there was no evidence of associations with total, colorectal and breast cancers.

Soy, red clover, and isoflavones and breast cancer: a systematic review

BACKGROUND

Soy and red clover isoflavones are controversial due to purported estrogenic activity and possible effects on breast cancer. We conducted a systematic review of soy and red clover for efficacy in improving menopausal symptoms in women with breast cancer, and for potential impact on risk of breast cancer incidence or recurrence.

METHODS

We searched MEDLINE, Embase, the Cochrane Library, and AMED from inception to March 2013 for human interventional or observational data pertaining to the safety and efficacy of soy and red clover isoflavones in patients with or at risk of breast cancer.

RESULTS

Of 4179 records, we included a total of 131 articles: 40 RCTs, 11 uncontrolled trials, and 80 observational studies. Five RCTs reported on the efficacy of soy for hot flashes, showing no significant reductions in hot flashes compared to placebo. There is lack of evidence showing harm from use of soy with respect to risk of breast cancer or recurrence, based on long term observational data. Soy intake consistent with that of a traditional Japanese diet (2-3 servings daily, containing 25-50mg isoflavones) may be protective against breast cancer and recurrence. Human trials show that soy does not increase circulating estradiol or affect estrogen-responsive target tissues. Prospective data of soy use in women taking tamoxifen does not indicate increased risk of recurrence. Evidence on red clover is limited, however existing studies suggest that it may not possess breast cancer-promoting effects.

CONCLUSION

Soy consumption may be associated with reduced risk of breast cancer incidence, recurrence, and mortality. Soy does not have estrogenic effects in humans. Soy intake consistent with a traditional Japanese diet appears safe for breast cancer survivors. While there is no clear evidence of harm, better evidence confirming safety is required before use of high dose (≥ 100 mg) isoflavones can be recommended for breast cancer patients.

Association between dietary fiber intake and physical performance in older adults: a nationwide study in Taiwan

Background

Physical performance is a major determinant of health in older adults, and is related to lifestyle factors. Dietary fiber has multiple health benefits. It remains unclear whether fiber intake is independently linked to superior physical performance. We aimed to assess the association between dietary fiber and physical performance in older adults.

Methods

This was a cross-sectional study conducted with community-dwelling adults aged 55 years and older (n=2680) from the ongoing Healthy Aging Longitudinal Study (HALST) in Taiwan 2008-2010. Daily dietary fiber intake was assessed using a validated food frequency questionnaire. Physical performance was determined objectively by measuring gait speed, 6-minute walk distance, timed “up and go” (TUG), summary performance score, hand grip strength.

Results

Adjusting for all potential confounders, participants with higher fiber intake had significantly faster gait speed, longer 6-minute walk distance, faster TUG, higher summary performance score, and higher hand grip strength (all P <.05). Comparing with the highest quartile of fiber intake, the lowest quartile of fiber intake was significantly associated with the lowest sex-specific quartile of gait speed (adjusted OR, 2.18 in men [95% CI, 1.33-3.55] and 3.65 in women [95% CI, 2.20-6.05]), 6-minute walk distance (OR, 2.40 in men [95% CI, 1.38-4.17] and 4.32 in women [95% CI, 2.37-7.89]), TUG (OR, 2.42 in men [95% CI, 1.43-4.12] and 3.27 in women [95% CI, 1.94-5.52]), summary performance score (OR, 2.12 in men [95% CI, 1.19-3.78] and 5.47 in women [95% CI, 3.20-9.35]), and hand grip strength (OR, 2.64 in men [95% CI, 1.61-4.32] and 4.43 in women [95% CI, 2.62-7.50]).

Conclusions

Dietary fiber intake was independently associated with better physical performance.

Nationwide surveillance in uterine cancer: survival analysis and the importance of birth cohort: 30-year population-based registry in Taiwan

Introduction

Uterine cancer was the most rapidly increasing malignancy and the second most common gynecologic malignancy in Taiwan.

Methods

We analyzed the secular trend of uterine cancer incidence and compare the survival of women with uterine carcinomas and uterine sarcomas in Taiwan. Data on women diagnosed with uterine cancer between 1979 and 2008 were obtained from the Taiwan cancer registry. Survival data were analyzed by using Kaplan-Meier and Cox proportional hazards regression methods.

Results

Records of 11,558 women with uterine carcinomas and 1,226 women with uterine sarcomas were analyzed. The age-adjusted incidence rate of endometrioid adenocarcinoma increased from 0.83 per 100,000 women per year between 1979 and 1983 to 7.50 per 100,000 women per year between 2004 and 2008. The 5-year survival rate of women with endometrioid adenocarcinoma (83.2%) was higher than that for women with clear cell carcinoma (58.3%), serous carcinoma (54.4%), and carcinosarcoma (35.2%) (p<0.0001, log-rank test). The 5-year survival rates of women with low grade endometrial stromal sarcoma, endometrial stromal sarcoma, leiomyosarcoma (LMS), and adenosarcoma were 97.5%, 73.5%, 60.1%, and 77.2%, respectively (p<0.0001, log rank test). The histologic type of endometrioid adenocarcinoma, young age, and treatment period after 2000 were independent, favorable prognostic factors in women with uterine carcinomas by multivariate analysis. The histologic type of LMS, old age, and treatment period after 2000 were independent, poor prognostic factors in women with uterine sarcomas by multivariate analysis.

Conclusions

An increase over time in the number of patients with endometrioid adenocarcinomas was noted in this 30-year, nationwide, population-based study. Histologic type, age and treatment period were survival factors for uterine cancers. A more comprehensive assessment of uterine cancers and patient care should be undertaken on this increasingly common type of cancer.

The emerging epidemic of estrogen-related cancers in young women in a developing Asian country

The incidence of breast and genital tract cancers is increasing among Taiwanese women, but the age specificity and histopathological features of these cancers have not been determined. We used a descriptive epidemiological method and data from the Taiwan Cancer Registry (1979-2007) to examine secular trends in the age-specific incidences of female breast cancer, three major female genital tract cancers and the histopathological subtypes of these cancers. Age-specific incidence rates in the United States (1978-2002) were used as an external reference, and the incidence rates of all malignancies and of malignant brain tumors were used as internal references. We found that age-adjusted incidence rates of female breast, uterine, and ovarian cancers increased in Taiwan from 1979 to 2007, whereas the incidence of cervical cancer decreased after 1998. The largest increase was observed for ductal and lobular carcinomas of the breast and endometrioid carcinomas of the uterus and ovary in women ≤55 years, all of these tumors show a high prevalence of hormone receptor expressions. In addition, hormone-receptor-positive rates of breast cancer were uniquely higher in younger, as opposed to older, Taiwanese women. These findings indicate that estrogen-related cancers rapidly emerge in young women in Taiwan and that incidence rates are catching up with that of women living in the United States.

Retinol, vitamins A, C, and E and breast cancer risk: a meta-analysis and meta-regression

OBJECTIVE

To comprehensively summarize the associations between retinol, vitamins A, C, and E and breast cancer, and quantitatively estimate their dose-response relationships.

METHODS

We searched PubMed, Embase, and Cochrane databases (from January 1982 to 15 March 2011) and the references of the relevant articles in English with sufficient information to estimate relative risk or odds ratio and the 95% confidence intervals, and comparable categories of vitamins. Two reviewers independently extracted data using a standardized form, with any discrepancy adjudicated by the third reviewer.

RESULTS

Overall, 51 studies met the inclusion criteria. Comparing the highest with the lowest intake, total vitamin A intake reduced the breast cancer risk by 17% (pooled OR = 0.83, 95% CI: 0.78-0.88). Further subgroup analysis based on study design did not change the significant reduction. Although the dietary vitamin A, dietary vitamin E, and total vitamin E intake all reduced breast cancer risk significantly when data from all studies were pooled, the results became nonsignificant when data from cohort studies were pooled. The significant association between total retinol intake and breast cancer in all studies became nonsignificant in case-control studies but remain significant in cohort studies. No significant dose-response relationship was observed in the higher intake of these vitamins with reduced breast cancer risk.

CONCLUSIONS

Our results indicate that both the total intake of vitamin A and retinol could reduce breast cancer risk. However, associations between other vitamins and breast cancer seem to be limited.

Meat and egg consumption and risk of breast cancer among Chinese women

OBJECTIVE

The association between meat and egg consumption and breast cancer risk has been examined in previous studies, but the results were inconsistent. We conducted a hospital-based case-control study during June 2007 to August 2008 among Guangdong Chinese women to investigate associations between meat and egg intake and breast cancer risk.

METHODS

Four hundred and thirty-eight consecutively recruited cases with primary breast cancer were frequency matched to 438 controls by age (5-year interval) and residence (rural/urban). Dietary intake was assessed by face-to-face interviews using a validated food frequency questionnaire. Odds ratios (ORs) and 95% confidence interval (CI) were obtained by using multiple unconditional logistic regression adjusted for various dietary and nondietary confounders.

RESULTS

We observed a borderline increased association of processed meat intake with breast cancer risk (trend test p = 0.066). The multivariate-adjusted OR of breast cancer risk for the highest versus the lowest quartile was 1.44 (95% CI = 0.97–2.15). No significant association was found between total and red meat, poultry, fish, and egg intake and risk.

CONCLUSIONS

This study suggested that processed meat intake was associated with a possible increased risk of breast cancer. There was no significant association between consumption of total and red meat, poultry, fish, or egg with breast cancer risk.

Synthesis and antiproliferative evaluation of 2,3-diarylquinoline derivatives

A number of 2,3-diarylquinoline derivatives were synthesized and evaluated for antiproliferative activities against the growth of six cancer cell lines including human hepatocellular carcinoma (Hep G2 and Hep 3B), non-small cell lung cancer (A549 and H1299), and breast cancer (MCF-7 and MDA-MB-231) cell lines. The preliminary results indicated that 6-fluoro-2,3-bis{4-[2-(piperidin-1-yl)ethoxy]phenyl}quinoline (16b) was one of the most active compounds against the growth of Hep 3B, H1299, and MDA-MB-231 with a GI(50) value of 0.71, 1.46, and 0.72 μM respectively which was more active than tamoxifen. Further investigations have shown that 16b induced cell cycle arrest at G2/M phase followed by DNA fragmentation via an increase in the protein expression of Bad, Bax and decrease in Bcl-2, and PARP which consequently cause cell death.

Secular trends in breast cancer mortality in five East Asian populations: Hong Kong, Japan, Korea, Singapore and Taiwan

Breast cancer risk is increasing in most Asian female populations, but little is known about the long-term mortality trend of the disease among these populations. We extracted data for Hong Kong (1979-2005), Japan (1963-2006), Korea (1985-2006), and Singapore (1963-2006) from the World Health Organization (WHO) mortality database and for Taiwan (1964-2007) from the Taiwan cancer registry. The annual age-standardized, truncated (to > or =20 years) breast cancer death rates for 11 age groups were estimated and joinpoint regression was applied to detect significant changes in breast cancer mortality. We also compared age-specific mortality rates for three calendar periods (1975-1984, 1985-1994, and 1995-2006). After 1990, breast cancer mortality tended to decrease slightly in Hong Kong and Singapore except for women aged 70+. In Taiwan and Japan, in contrast, breast cancer death rates increased throughout the entire study period. Before the 1990s, breast cancer death rates were almost the same in Taiwan and Japan; thereafter, up to 1996, they rose more steeply in Taiwan and then they began rising more rapidly in Japan than in Taiwan after 1996. The most rapid increases in breast cancer mortality, and for all age groups, were in Korea. Breast cancer mortality trends are expected to maintain the secular trend for the next decade mainly as the prevalence of risk factors changes and population ages in Japan, Korea, and Taiwan. Early detection and treatment improvement will continue to reduce the mortality rates in Hong Kong and Singapore as observed in Western countries.

Molecular subtypes of breast cancer emerging in young women in Taiwan: evidence for more than just westernization as a reason for the disease in Asia

BACKGROUND

In the past two decades, the incidence of breast cancer in young Taiwanese females has been rapidly increasing, approaching the risk level of western countries. As a first step to investigate the possible etiology, we examined the molecular subtypes of female breast cancer in Taiwan.

METHODS

This study included 1,028 consecutive patients with breast cancer diagnosed in National Taiwan University Hospital between 2004 and 2006. Estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2, cytokeratin 5/6, and epidermal growth factor receptor expression and/or gene amplification were analyzed.

RESULTS

Younger (<or=50 years) breast cancer patients had a higher prevalence of luminal A (67% versus 57%; P < 0.001) and a lower prevalence of basal-like subtype (9% versus 17%; P < 0.001) compared with older (>50 years) patients. The higher prevalence of luminal A subtype was mainly attributed to a higher ER (75% versus 63%; P < 0.001) and PR (47% versus 33%; P < 0.001) expression rate in younger patients than older patients. Tumors with histologic grade 3 were less prevalent in younger patients than in older patients (23% versus 30%; P = 0.01). For very young (<35 years) patients, the molecular subtype distribution, ER and/or PR expression rate, and histologic grade were not significantly different from those of less young (35-50 years) patients.

CONCLUSIONS

Young breast cancer patients in Taiwan are characterized by a high prevalence of luminal A subtype and low prevalence of histologic grade 3 tumor and/or basal-like subtype. These features are distinct from young breast cancer patients in western countries.

Perspectives on the soy-breast cancer relation

There has been considerable investigation of the potential for soy foods to reduce risk of breast cancer. Initial enthusiasm for this research was partially based on the historically low incidence rates of breast cancer and high soy food intake in Japan. There are several putative soybean chemopreventive agents, but most cancer research has focused on isoflavones. Isoflavones possess both hormonal and nonhormonal properties relevant to carcinogenesis. Recent epidemiologic analyses indicate that among Asians high soy intake is associated with an approximate one-third reduction in the risk of both pre- and postmenopausal breast cancer. However, several lines of evidence suggest that to derive maximum protection against breast cancer, soy must be consumed early in life. This evidence is consistent with the lack of significant effects noted in clinical studies that have evaluated the effects of isoflavone-containing products on breast cancer risk markers. Isoflavones may exert their putative protective effects by stimulating breast cell differentiation in a manner similar to that which is thought to occur during early pregnancy. Finally, the ability of the isoflavone genistein to stimulate the growth of mammary tumors in ovariectomized athymic nude mice implanted with estrogen-sensitive breast cancer cells has raised concern that soy foods, and especially isoflavone supplements, are contraindicated for patients with breast cancer and women at high risk of breast cancer. However, findings from clinical studies, in which breast biopsies have been taken or breast tissue density measured after isoflavone exposure, are reassuring and contrast with the proliferative effects of conventional combined hormone therapy, although understanding of the effect of soy and isoflavones on breast tissues remains imprecise.

Results based on 124 cases of breast cancer and 97 controls from Taiwan suggest that the single nucleotide polymorphism (SNP309) in the MDM2 gene promoter is associated with earlier onset and increased risk of breast cancer

Background

It has been suggested that the single nucleotide polymorphism 309 (SNP309, T -> G) in the promoter region of the MDM2 gene is important for tumor development; however, with regards to breast cancer, inconsistent associations have been reported worldwide. It is speculated that these conflicting results may have arisen due to different patient subgroups and ethnicities studied. For the first time, this study explores the effect of the MDM2 SNP309 genotype on Taiwanese breast cancer patients.

Methods

Genomic DNA was obtained from the whole blood of 124 breast cancer patients and 97 cancer-free healthy women living in Taiwan. MDM2 SNP309 genotyping was carried out by restriction fragment length polymorphism (RFLP) assay. The multivariate logistic regression and the Kaplan-Meier method were used for analyzing the risk association and significance of age at diagnosis among different MDM2 SNP309 genotypes, respectively.

Results

Compared to the TT genotype, an increased risk association with breast cancer was apparent for the GG genotype (OR = 3.05, 95% CI = 1.04 to 8.95), and for the TG genotype (OR = 2.12, 95% CI = 0.90 to 5.00) after adjusting for age, cardiovascular disease/diabetes, oral contraceptive usage, and body mass index, which exhibits significant difference between cases and controls. Furthermore, the average ages at diagnosis for breast cancer patients were 53.6, 52 and 47 years for those harboring TT, TG and GG genotypes, respectively. A significant difference in median age of onset for breast cancer between GG and TT+TG genotypes was obtained by the log-rank test (p = 0.0067).

Conclusion

Findings based on the current sample size suggest that the MDM2 SNP309 GG genotype may be associated with both the risk of breast cancer and an earlier age of onset in Taiwanese women.

Vitamin supplement use and risk for breast cancer: the Shanghai Breast Cancer Study

OBJECTIVE

The influence of vitamin supplements on breast cancer risk is unclear and the interactive effects of dietary and supplemental sources are unknown. This study investigated (1) the association between self-reported vitamin supplement use (multivitamin, A, B, C, and E) and breast cancer and (2) the combined effect of vitamin supplements in relation to dietary vitamin intakes on breast cancer risk.

METHODS

The Shanghai Breast Cancer Study was a population-based case-control study conducted in Shanghai in 1996-1998 (Phase I) and 2002-2004 (Phase II). Participants were aged 25-64 (Phase I) and 20-70 years (Phase II). The analyses included 3,454 incident breast cancer cases and 3,474 controls. Unconditional logistic regression models were used to determine adjusted odds ratios (ORs) for breast cancer risk associated with vitamin supplement use.

RESULTS

Overall, breast cancer risk was not related to any vitamin supplement intake. However, a 20% reduction in breast cancer risk was observed with vitamin E supplement use among women with low-dietary vitamin E intake (OR = 0.8; 95% confidence interval (CI), 0.6-1.0). A non-significant 20% risk reduction was observed among vitamin B supplement users with low B dietary intake (OR = 0.8; 95% CI, 0.6-1.1). Frequent use of a vitamin B supplement was adversely associated with breast cancer risk among those with high dietary vitamin B intake (OR = 1.4; 95% CI: 0.9-2.1; P for interaction = 0.07).

CONCLUSIONS

This study suggests that vitamins E and B supplements may confer protection against breast cancer among women who have low dietary intake of those vitamins.

Soy intake and breast cancer risk in Singapore Chinese Health Study

We investigated the effects of soy isoflavone intake on breast cancer in a prospective study of 35 303 Singapore Chinese women enrolled during April 1993 to December 1998 in the Singapore Chinese Health Study. At recruitment, each subject was personally administered a validated semiquantitative food frequency questionnaire covering 165 food and beverage items. As of December 31 2005, 629 had developed breast cancer following an accumulation of 338 242 person-years. Using Cox regression and adjusting for age at interview, year of interview, dialect group, education, family history of breast cancer, age when periods became regular, parity, menopausal status, body mass index (BMI), n-3 fatty acid, and other covariates, we found breast cancer risk was reduced significantly in association with high soy intake. Relative to women with lower (below median) soy intake (<10.6 mg isoflavone per 1000 Kcal), women with higher (above median) intake showed a significant 18% risk reduction (relative risk (RR)=0.82, 95% confidence interval (CI)=0.70–0.97). This inverse association was apparent mainly in postmenopausal women (RR=0.74, 95% CI=0.61–0.90), and was not observed in premenopausal women (RR=1.04, 95% CI=0.77–1. 40). Among postmenopausal women, the soy–breast cancer association was stronger in those above median BMI (RR=0.67, 95% CI=0.51–0.88) than in leaner women (RR=0.83, 95% CI=0.62–1.11). Duration of follow-up modified the soy–breast cancer association, the effect being twice as large among women with 10+ vs fewer years of follow-up. Neither oestrogen nor progesterone receptor status of the tumours materially influenced the association. These prospective findings suggest that approximately 10 mg of isoflavones per day, obtained in a standard serving of tofu, may have lasting beneficial effects against breast cancer development.

Genotype X diet interactions in mice predisposed to mammary cancer: II. Tumors and metastasis

High dietary fat intake and obesity may increase the risk of susceptibility to certain forms of cancer. To study the interactions of dietary fat, obesity, and metastatic mammary cancer, we created a population of F(2) mice cosegregating obesity QTL and the MMTV-PyMT transgene. We fed the F(2) mice either a very high-fat or a matched-control-fat diet, and we measured growth, body composition, age at mammary tumor onset, tumor number and severity, and formation of pulmonary metastases. SNP genotyping across the genome facilitated analyses of QTL and QTL x diet interaction effects. Here we describe effects of diet on mammary tumor and metastases phenotypes, mapping of tumor/metastasis modifier genes, and the interaction between dietary fat levels and effects of cancer modifiers. Results demonstrate that animals fed a high-fat diet are not only more likely to experience decreased mammary cancer latency but increased tumor growth and pulmonary metastases occurrence over an equivalent time. We identified 25 modifier loci for mammary cancer and pulmonary metastasis, likely representing 13 unique loci after accounting for pleiotropy, and novel QTL x diet interactions at a majority of these loci. These findings highlight the importance of accurately modeling not only the human cancer characteristics in mice but also the environmental exposures of human populations.

Epidemiology of soy exposures and breast cancer risk

Most of the early studies published on soy and breast cancer were not designed to test the effect of soy; the assessment of soy intake was usually crude and few potential confounders were considered in the analysis. In this review, we focused on studies with relatively complete assessment of dietary soy exposure in the targeted populations and appropriate consideration for potential confounders in the statistical analysis of study data. Meta-analysis of the 8 (1 cohort, 7 case-control) studies conducted in high-soy-consuming Asians show a significant trend of decreasing risk with increasing soy food intake. Compared to the lowest level of soy food intake (<or=5 mg isoflavones per day), risk was intermediate (OR=0.88, 95% confidence interval (CI)=0.78-0.98) among those with modest ( approximately 10 mg isoflavones per day) intake and lowest (OR=0.71, 95% CI=0.60-0.85) among those with high intake (>or=20 mg isoflavones per day). In contrast, soy intake was unrelated to breast cancer risk in studies conducted in the 11 low-soy-consuming Western populations whose average highest and lowest soy isoflavone intake levels were around 0.8 and 0.15 mg per day, respectively. Thus, the evidence to date, based largely on case-control studies, suggest that soy food intake in the amount consumed in Asian populations may have protective effects against breast cancer.

Urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) and genetic polymorphisms in breast cancer patients

Reactive oxygen species (ROS) causes damage to DNA, but the role of ROS in breast carcinoma is still not clear. The objective of this study was to measure the urinary 8-OHdG levels of breast cancer patients at each stage of carcinogenesis and assess its association with the development of breast cancer. Sixty patients with malignant breast tumors were matched with 60 control subjects of the same ages in this case control study. Urinary 8-OHdG levels were significantly higher among breast cancer patients than among the control subjects, after making adjustments for confounders such as smoking, coffee consumption and use of oral contraceptives. The breast cancer patients were divided into three groups based on the stages of their cancer; urinary 8-OHdG levels decreased with each stage of breast carcinoma. Using multiple regression and logistic models adjusted for other covariates, urinary 8-OHdG levels significantly correlated with the development of breast cancer. However, it was found that breast cancer was not significantly influenced by CYP1A1, CYP1M1 or NAT2 polymorphisms. In conclusion, it was found that oxygen radical generation occurred within carcinoma cells, but the role of polymorphism of specific genes in the development of breast cancer should be evaluated.

Soyfood Intake in the Prevention of Breast Cancer Risk in Women: A Meta-Analysis of Observational Epidemiological Studies

Many studies have suggested that the intake of soy products may protect against the occurrence of breast cancer because of the considerable amount of isoflavones they contain. To review the results of the observational studies, we performed this meta-analysis of the relevant literature. We searched Medline for reports that examined the association between soyfood consumption (or isoflavone intake) and breast cancer risk from January 1966 to April 2006. The random-effects model was used to estimate the pooled relative risk (RR). Twenty-one independent studies (14 case-control studies and 7 cohort studies) were included in the final analysis. The pooled RR of breast cancer for soyfood intake was 0.75 with a 95% CI of 0.59-0.95. As the main types of soyfood in Japan and China, tofu and miso showed clear protective effects. Isoflavone intake resulted in a 20% decrease in risk (RR = 0.81, 95% CI 0.67-0.99). The pooled RR varied little according to study stratification. When the studies published in Japanese and Chinese were added, the inverse associations between soyfood, tofu and breast cancer risk became slightly stronger. The weak association of miso was possibly due to the high concentration of salt in miso soup. In the present analysis, we did not find strong evidence for publication bias in the combination of the studies. This meta-analysis supported the hypotheses that soyfood intake may be associated with a decreased risk of breast cancer due to the isoflavones. Further epidemiological studies need to be conducted with more comprehensive information about the soyfood, and more accurate assessment of the isoflavones.