Risk factors for breast cancer by oestrogen receptor status: a population-based case-control study

SIRT1 mediates breast cancer development and tumorigenesis controlled by estrogen-related receptor β

Silent mating type information regulation 2 homolog 1 (SIRT1) is a class III histone deacetylase (HDAC) that is NAD + dependent and essential for metabolism, senescence, and cell survival. SIRT1 is overexpressed in several cancers, including breast cancer. SIRT1 is a well-known target gene of the estrogen receptor alpha (ER alpha) and is closely related to ER alpha deacetylation. Transcription factor Estrogen-related receptors (ERRs) share sequence homology with ERs in the DNA-binding domain, therefore, the possibility of sharing target genes between them is high. Our current research aims to gain insight into the function of ERRβ in regulating the activity of SIRT1 during the progression of breast cancer. ER-positive (ER + ve) breast cancer cells and tissues had considerably enhanced SIRT1 expression. Six potential ERRE sites were identified by analysis of the 5' upstream region of SIRT1, and both in vitro and in vivo experiments supported their presence. We found SIRT1 to be up-regulated in ERRβ overexpressed ER + ve breast cancer cells. Furthermore, our findings suggested that ectopic production of ERR and PCAF would increase SIRT1 activity. Our findings also indicated that ectopic production of ERRβ and PCAF increased SIRT1 activity. With sufficient evidence demonstrating the substantial involvement of SIRT1 in cell proliferation, migration, and colony formation capability, we were also able to illustrate the tumorigenic role of SIRT1. Overall, our findings highlight SIRT1's tumorigenic influence on breast cancer and suggest that SIRT1 inhibitors might serve as potential therapeutic drugs for the treatment of breast cancer.

The effect of smoking on biological change of recurrent breast cancer

BACKGROUND

The selection of treatment for a patient with breast cancer largely relies on the cancer subtype. However, this process is complicated by changes in tumor biology at relapse. Smoking has been identified as a risk factor for breast cancer. The direct effect of a tobacco component delivered via blood circulation on the mammary gland tissue and subsequent DNA damage have been proposed to explain the association between cigarette smoking and breast cancer carcinogenesis. This postulation is supported by both tissue culture and animal studies demonstrating that the associated DNA damage further alters breast cancer cells, as indicated by an increased proliferative capacity and malignant transformation. In this study, we aimed to explore the relationship between changes in Estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) each receptor at recurrence, and smoking and the prognosis after recurrence.

METHODS

This retrospective study included 989 patients with primary breast cancer who developed relapse after surgery and 50 patients who underwent regenerative biopsy or surgery from December 2007 to March 2018. ER, PgR, and HER2 expression in the primary and recurrent lesions was evaluated using immunohistochemistry, and the correlations of these expression patterns with smoking history (pack-years) were examined.

RESULTS

When ER was evaluated in recurrent tumors, negative and positive conversions were recognized in 3 (6.0%) and 1 patient (2.0%), respectively. When PgR was evaluated, negative conversion was recognized in 15 patients (30.0%). When HER2 was evaluated, positive conversion was recognized in 6 patients (12.0%). Consequently, we observed a change in the intrinsic subtype in in 5 patients with recurrent tumors (10.0%). Although most clinical factors were not correlated with smoking, a positive conversion of HER2 in recurrence was significantly more frequent among smokers than among non-smokers (p = 0.024).

CONCLUSIONS

Biological changes during breast cancer recurrence should be given careful clinical consideration because they affect treatment after recurrence. Our results suggest that smoking may induce increased HER2 expression in recurrent breast tumors.

A prospective investigation of oral contraceptive use and breast cancer mortality: findings from the Swedish women's lifestyle and health cohort

BACKGROUND

The association between oral contraceptive (OC) use and long-term mortality remains uncertain and previous studies have reported conflicting findings. We aim to assess the long-term impact of OC use on all-cause and cancer-specific mortality.

METHODS

Out of 49,259 participants, we analysed data on 2120 (4.3%) women diagnosed with first primary breast cancer between 1993 and 2012, in the Swedish Women's Lifestyle and Health Study. Kaplan-Meier plots were used to graph the hazard of mortality in association with oral contraceptives use, stage of disease and hormone receptors status at diagnosis. Cox proportional hazard model were used to estimate hazard ratios (HR) between OC use and all-cause mortality. The same association was studied for breast cancer-specific mortality by modelling the log cumulative mortality risk, adjusting for clinical stage at diagnosis, hormone receptor status, body mass index and smoking.

RESULTS

Among 2120 women with breast cancer, 1268 (84%) reported ever use of OC and 254 died within 10 years of diagnosis. The risk of death for OC ever-users relative to never-users was: HR = 1.13 (95% CI: 0.66-1.94) for all-cause mortality and HR = 1.29 (95% CI: 0.53-3.18) for breast cancer-specific mortality. A high percentage of women (42.9%) were diagnosed at early stage disease (stage I).

CONCLUSIONS

Among women with primary breast cancer, OC ever-users compared to never- users did not have a higher all-cause or breast cancer specific-mortality, after the adjustment of risk factors.

Clinical verification of the relationship between smoking and the immune microenvironment of breast cancer

Background

The immune tumor microenvironment (iTME) is thought to affect the response to chemotherapy, and tumor-infiltrating lymphocytes (TILs) are often used as an indicator to evaluate the iTME. Smoking is involved in carcinogenesis, the relationship between smoking and the iTME of lung cancer has been reported. We hypothesized that smoking would affect the iTME of breast cancer and aimed to examine this relationship based on the amount of pre-diagnosis smoking and the subsequent effects on treatment response and prognosis.

Methods

This retrospective study evaluated data from 149 patients who underwent preoperative chemotherapy for triple-negative or HER2-enriched breast cancer. TILs were assessed in biopsy specimens at diagnosis. The data of all patients were used to calculate each patient’s smoking amount based on pack-years.

Results

Relative to the low smoking group, the high smoking group had a significant greater TILs density (p = 0.043) and a significantly better pathological complete response (pCR) rate (p = 0.042). However, there was no significant difference according to smoking amount in disease-free survival (p = 0.114) or overall survival (p = 0.347).

Conclusions

Smoking may influence the iTME, with an activated iTME being associated with pCR rate. Therefore, controlled activation of the microenvironment in this setting may help improve patients’ prognosis.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1773-y) contains supplementary material, which is available to authorized users.

Estrogen receptor α dependent regulation of estrogen related receptor β and its role in cell cycle in breast cancer

BACKGROUND

Breast cancer (BC) is highly heterogeneous with ~ 60-70% of estrogen receptor positive BC patient's response to anti-hormone therapy. Estrogen receptors (ERs) play an important role in breast cancer progression and treatment. Estrogen related receptors (ERRs) are a group of nuclear receptors which belong to orphan nuclear receptors, which have sequence homology with ERs and share target genes. Here, we investigated the possible role and clinicopathological importance of ERRβ in breast cancer.

METHODS

Estrogen related receptor β (ERRβ) expression was examined using tissue microarray slides (TMA) of Breast Carcinoma patients with adjacent normal by immunohistochemistry and in breast cancer cell lines. In order to investigate whether ERRβ is a direct target of ERα, we investigated the expression of ERRβ in short hairpin ribonucleic acid knockdown of ERα breast cancer cells by western blot, qRT-PCR and RT-PCR. We further confirmed the binding of ERα by electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), Re-ChIP and luciferase assays. Fluorescence-activated cell sorting analysis (FACS) was performed to elucidate the role of ERRβ in cell cycle regulation. A Kaplan-Meier Survival analysis of GEO dataset was performed to correlate the expression of ERRβ with survival in breast cancer patients.

RESULTS

Tissue microarray (TMA) analysis showed that ERRβ is significantly down-regulated in breast carcinoma tissue samples compared to adjacent normal. ER + ve breast tumors and cell lines showed a significant expression of ERRβ compared to ER-ve tumors and cell lines. Estrogen treatment significantly induced the expression of ERRβ and it was ERα dependent. Mechanistic analyses indicate that ERα directly targets ERRβ through estrogen response element and ERRβ also mediates cell cycle regulation through p18, p21^cip and cyclin D1 in breast cancer cells. Our results also showed the up-regulation of ERRβ promoter activity in ectopically co-expressed ERα and ERRβ breast cancer cell lines. Fluorescence-activated cell sorting analysis (FACS) showed increased G0/G1 phase cell population in ERRβ overexpressed MCF7 cells. Furthermore, ERRβ expression was inversely correlated with overall survival in breast cancer. Collectively our results suggest cell cycle and tumor suppressor role of ERRβ in breast cancer cells which provide a potential avenue to target ERRβ signaling pathway in breast cancer.

CONCLUSION

Our results indicate that ERRβ is a negative regulator of cell cycle and a possible tumor suppressor in breast cancer. ERRβ could be therapeutic target for the treatment of breast cancer.

Breast Cancer Estrogen and Progesterone Receptors: Associations with Patients' Clinical and Epidemiologic Characteristics

A total of 1095 patients with operable breast cancer and en-rolled in a randomized clinical trial were analysed for estrogen (ER) and progesterone (PgR) receptor content of their primary tumor, and the relationships between steroid receptor status and several epidemiologic characteristics were studied. The proportion of ER+ and median ER levels increased with age: compared to women younger than 40, those aged 66 or more were approximately three times more likely to have an ER+ tumor (OR = 3.0, 95% C.I. = 1.6–5.7). This difference tended to be more marked after comparison between patients with ER > 100 fmol/mg protein and ER- within the same age groups: OR = 7.04, 95 % C.I. = 2.89–17.12. No association emerged between age and PgR. ER status and concentrations were independent of menopausal status after adjustment for age, whereas the proportion of PgR+ and PgR levels were significantly lower in postmenopausal patients of the same age. The distribution of ER and PgR profiles was similar in relation to family history of breast cancer, reproductive events and other selected epidemiologic characteristics of the patients.

Prediagnostic Smoking Is Associated with Binary and Quantitative Measures of ER Protein and ESR1 mRNA Expression in Breast Tumors

Background: Smoking is a possible risk factor for breast cancer and has been linked to increased risk of estrogen receptor-positive (ER⁺) disease in some epidemiologic studies. It is unknown whether smoking has quantitative effects on ER expression.Methods: We examined relationships between smoking and ER expression from tumors of 1,888 women diagnosed with invasive breast cancer from a population-based study in North Carolina. ER expression was characterized using binary (±) and continuous measures for ER protein, ESR1 mRNA, and a multigene luminal score (LS) that serves as a measure of estrogen signaling in breast tumors. We used logistic and linear regression models to estimate temporal and dose-dependent associations between smoking and ER measures.Results: The odds of ER⁺, ESR1⁺, and LS⁺ tumors among current smokers (at the time of diagnosis), those who smoked 20 or more years, and those who smoked within 5 years of diagnosis were nearly double those of nonsmokers. Quantitative levels of ESR1 were highest among current smokers compared with never smokers overall [mean (log₂) = 9.2 vs. 8.7, P < 0.05] and among ER⁺ cases; however, we did not observe associations between smoking measures and continuous ER protein expression.Conclusions: In relationship to breast cancer diagnosis, recent smoking was associated with higher odds of the ER⁺, ESR1⁺, and LS⁺ subtype. Current smoking was associated with elevated ESR1 mRNA levels and an elevated LS, but not with altered ER protein.Impact: A multigene LS and single-gene ESR1 mRNA may capture tumor changes associated with smoking. Cancer Epidemiol Biomarkers Prev; 27(1); 67-74. ©2017 AACR.

Breast tumor DNA methylation patterns associated with smoking in the Carolina Breast Cancer Study

PURPOSE

Tobacco smoking is a risk factor in several cancers, yet its roles as a putative etiologic exposure or poor prognostic factor in breast cancer are less clear. Altered DNA methylation contributes to breast cancer development and may provide a mechanistic link between smoking and gene expression changes leading to cancer development or progression.

METHODS

Using a cancer-focused array, we examined methylation at 933 CpGs in 517 invasive breast tumors in the Carolina Breast Cancer Study to determine whether methylation patterns differ by exposure to tobacco smoke. Multivariable generalized linear regression models were used to compare tumor methylation profiles between smokers and never smokers, overall, or stratified on hormone receptor (HR) status.

RESULTS

Modest differences in CpG methylation were detected at p < 0.05 in breast tumors from current or ever smokers compared with never smokers. In stratified analyses, HR- tumors from smokers exhibited primarily hypomethylation compared with tumors from never smokers; hypomethylation was similarly detected within the more homogeneous basal-like subtype. Most current smoking-associated CpG loci exhibited methylation levels in former smokers that were intermediate between those in current and never smokers and exhibited progressive changes in methylation with increasing duration of smoking. Among former smokers, restoration of methylation toward baseline (never smoking) levels was observed with increasing time since quitting. Moreover, smoking-related hypermethylation was stronger in HR+ breast tumors from blacks than in whites.

CONCLUSIONS

Our results suggest that breast tumor methylation patterns differ with tobacco smoke exposure; however, additional studies are needed to confirm these findings.

Effect of Genetic Polymorphisms and Long-Term Tobacco Exposure on the Risk of Breast Cancer

INTRODUCTION

Tobacco smoke contains many potentially harmful compounds that may act differently and at different stages in breast cancer development. The focus of this work was to assess the possible role of cigarette smoking (status, dose, duration or age at initiation) and polymorphisms in genes coding for enzymes involved in tobacco carcinogen metabolism (CYP1A1, CYP2A6) or in DNA repair (XRCC1, APEX1, XRCC3 and XPD) in breast cancer development.

METHODS

We designed a case control study with 297 patients, 217 histologically verified breast cancers (141 smokers and 76 non-smokers) and 80 healthy smokers in a cohort of Spanish women.

RESULTS

We found an association between smoking status and early age at diagnosis of breast cancer. Among smokers, invasive carcinoma subtype incidence increased with intensity and duration of smoking (all P_trend < 0.05). When smokers were stratified by smoking duration, we only observed differences in long-term smokers, and the CYP1A1 Ile462Ile genotype was associated with increased risk of breast cancer (OR = 7.12 (1.98-25.59)).

CONCLUSIONS

Our results support the main effect of CYP1A1 in estrogenic metabolism rather than in tobacco carcinogen activation in breast cancer patients and also confirmed the hypothesis that CYP1A1 Ile462Val, in association with long periods of active smoking, could be a breast cancer risk factor.

Active smoking and risk of Luminal and Basal-like breast cancer subtypes in the Carolina Breast Cancer Study

PURPOSE

Growing evidence suggests an association between active cigarette smoking and increased breast cancer risk. However, the weak magnitude of association and conflicting results have yielded uncertainty and it is unknown whether associations differ by breast cancer subtype.

METHODS

Using population-based case-control data from phases I and II of the Carolina Breast Cancer Study, we examined associations between self-reported measures of smoking and risk of Luminal and Basal-like breast cancers. We used logistic regression models to estimate case-control odds ratios (OR) and 95 % confidence intervals (CI).

RESULTS

Ever smoking (current and former) was associated with a weakly increased risk of Luminal breast cancer (OR 1.12, 95 % CI 0.92-1.36) and was not associated with risk of Basal-like breast cancer (OR 0.96, 95 % CI 0.69-1.32). Similarly, smoking duration of more than 20 years was associated with increased risk of Luminal (OR 1.51, 95 % CI 1.19-1.93), but not Basal-like breast cancer (OR 0.90, 95 % CI 0.57-1.43). When stratified by race, elevated odds ratios between smoking and Luminal breast cancer risk were found among black women across multiple exposure measures (ever smoking, duration, and dose); conversely, among white women odds ratios were attenuated or null.

CONCLUSIONS

Results from our study demonstrate a positive association between smoking and Luminal breast cancer risk, particularly among black women and women with long smoking histories. Addressing breast cancer heterogeneity in studies of smoking and breast cancer risk may elucidate associations masked in prior studies.

Breastfeeding and breast cancer risk by receptor status--a systematic review and meta-analysis

BACKGROUND

Breastfeeding is inversely associated with overall risk of breast cancer. This association may differ in breast cancer subtypes defined by receptor status, as they may reflect different mechanisms of carcinogenesis. We conducted a systematic review and meta-analysis of case-control and prospective cohort studies to investigate the association between breastfeeding and breast cancer by estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status.

DESIGN

We searched the PubMed and Scopus databases and bibliographies of pertinent articles to identify relevant articles and used random-effects models to calculate summary odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

This meta-analysis represents 27 distinct studies (8 cohort and 19 case-control), with a total of 36 881 breast cancer cases. Among parous women, the risk estimates for the association between ever (versus never) breastfeeding and the breast cancers negative for both ER and PR were similar in three cohort and three case-control studies when results were adjusted for several factors, including the number of full-term pregnancies (combined OR 0.90; 95% CI 0.82-0.99), with little heterogeneity and no indication of publication bias. In a subset of three adjusted studies that included ER, PR, and HER2 status, ever breastfeeding showed a stronger inverse association with triple-negative breast cancer (OR 0.78; 95% CI 0.66-0.91) among parous women. Overall, cohort studies showed no significant association between breastfeeding and ER+/PR+ or ER+ and/or PR+ breast cancers, although one and two studies (out of four and seven studies, respectively) showed an inverse association.

CONCLUSIONS

This meta-analysis showed a protective effect of ever breastfeeding against hormone receptor-negative breast cancers, which are more common in younger women and generally have a poorer prognosis than other subtypes of breast cancer. The association between breastfeeding and receptor-positive breast cancers needs more investigation.

Management of patients with hormone receptor-positive breast cancer with visceral disease: challenges and treatment options

Endocrine therapy is an important treatment option for women with hormone receptor-positive (HR+) advanced breast cancer (ABC), yet many tumors are either intrinsically resistant or develop resistance to these therapies. Treatment of patients with ABC presenting with visceral metastases, which is associated with a poor prognosis, is also problematic. There is an unmet need for effective treatments for this patient population. Although chemotherapy is commonly perceived to be more effective than endocrine therapy in managing visceral metastases, patients who are not in visceral crisis might benefit from endocrine therapy, avoiding chemotherapy-associated toxicities that might affect quality of life. To improve outcomes, several targeted therapies are being investigated in combination with endocrine therapy for patients with endocrine-resistant, HR+ ABC. Although available data have considered patients with HR+ ABC as a whole, there are promising data from a prespecified analysis of a Phase III study of everolimus (Afinitor(®)), a mammalian target of rapamycin (mTOR) inhibitor, in combination with exemestane (Aromasin(®)) in patients with visceral disease progressing after nonsteroidal aromatase inhibitor therapy. In this review, challenges and treatment options for management of HR+ ABC with visceral disease, including consideration of therapeutic approaches undergoing clinical investigation, will be assessed.

Alcohol and breast cancer: reconciling epidemiological and molecular data

Breast cancer is the most diagnosed cancer in women worldwide. Epidemiological studies have suggested a possible causative role of alcohol consumption as a risk factor for breast cancer. However, such conclusions should be interpreted with considerable caution for several reasons. While epidemiological studies can help identify the roots of health problems and disease incidence in a community, they are by necessity associative and cannot determine cause and effect relationships. In addition, all these studies rely on self-reporting to determine the amount and type of alcoholic beverage consumed, which introduces recall bias. This is documented in a recent study which stated that the apparent increased risk of cancer among light-moderate drinkers may be "substantially due to underreporting of intake." Another meta-analysis about alcohol and breast cancer declared "the modest size of the association and variation in results across studies leave the causal role of alcohol in question." Furthermore, breast cancer develops over decades; thus, correlations between alcohol consumption and breast cancer cannot be determined in epidemiological studies with windows of alcohol exposure that captures current or recent alcohol intake, after clinical diagnosis. Numerous risk factors are involved in breast carcinogenesis; some are genetic and beyond the control of a woman; others are influenced by lifestyle factors. Breast cancer is a heterogeneous and polygenic disease which is further influenced by epigenetic mechanisms that affect the transciptomes, proteomes and metabolomes, and ultimately breast cancer evolution. Environmental factors add another layer of complexity by their interactions with the susceptibility genes for breast cancer and metabolic diseases. The current state-of-knowledge about alcohol and breast cancer association is ambiguous and confusing to both a woman and her physician. Confronting the huge global breast cancer issue should be addressed by sound science. It is advised that women with or without a high risk for breast cancer should avoid overconsumption of alcohol and should consult with their physician about risk factors involved in breast cancer. Since studies associating moderate alcohol consumption and breast cancer are contradictory, a woman and her physician should weigh the risks and benefits of moderate alcohol consumption.

Modern reproductive patterns associated with estrogen receptor positive but not negative breast cancer susceptibility

It has long been accepted that modern reproductive patterns are likely contributors to breast cancer susceptibility because of their influence on hormones such as estrogen and the importance of these hormones in breast cancer. We conducted a meta-analysis to assess whether this ‘evolutionary mismatch hypothesis’ can explain susceptibility to both estrogen receptor positive (ER-positive) and estrogen receptor negative (ER-negative) cancer. Our meta-analysis includes a total of 33 studies and examines parity, age of first birth and age of menarche broken down by estrogen receptor status. We found that modern reproductive patterns are more closely linked to ER-positive than ER-negative breast cancer. Thus, the evolutionary mismatch hypothesis for breast cancer can account for ER-positive breast cancer susceptibility but not ER-negative breast cancer.

Cigarette smoking and breast cancer risk in relation to joint estrogen and progesterone receptor status: a case-control study in Japan

An association of cigarette smoking with breast cancer risk has been hypothesized. However, results from previous studies have been inconsistent. This case-control study investigated the association of cigarette smoking with breast cancer risk in terms of estrogen-receptor/progesterone-receptor (ER/PgR) status. From among female patients aged 30 years and over admitted to a single hospital in Japan between 1997 and 2011, 1,263 breast cancer cases (672 ER+/PgR+, 158 ER+/PgR-, 22 ER-/PgR+, 308 ER-/PgR- and 103 missing) and 3,160 controls were selected. History of smoking (ever, never), some smoking-related measures, and passive smoking from husbands (ever, never) were assessed using a self-administered questionnaire. Polytomous logistic regression and tests for heterogeneity across ER+/PgR + and ER-/PgR- were conducted. For any hormone receptor subtype, no significant association was observed between history of smoking (ever, never) and breast cancer risk. Analysis of smoking-related measures revealed that starting to smoke at an early age of ≤19 years was significantly associated with an increased risk of postmenopausal ER-/PgR- cancer (odds ratio = 7.01, 95% confidence interval: 2.07-23.73). Other measures of smoking such as the number of cigarettes per day, the duration of smoking, and start of smoking before the first birth were not associated with breast cancer risk for any receptor subtype. There was no association between passive smoking (ever, never) and breast cancer risk for any of the four subtypes. These results indicate that history of smoking and passive smoking from husbands may have no overall effect on breast cancer risk for any hormone receptor subtype. However, it is possible that women who start to smoke as teenagers may have a higher risk of developing postmenopausal ER-/PgR- cancer. Further studies are needed to clarify the association of smoking with breast cancer risk, especially the role of starting to smoke at an early age.

Socioeconomic disparities and breast cancer hormone receptor status

PURPOSE

Recent research, although inconsistent, indicates that socioeconomic status (SES) may be associated with hormone receptor (HR) status. This study aims to examine the association between SES and breast cancer HR status within and across racial/ethnic groups stratified by age at diagnosis and tumor stage.

METHODS

The study subjects were 184,602 women with incident breast cancer diagnosed during 2004-2007 and identified from the National Cancer Institute's Surveillance, Epidemiology and End Results program. Log-binomial regression assessed the risk of having breast tumors that were (1) HR-negative versus HR-positive and (2) HR-unknown versus HR-known between women who, at the time of diagnosis, were residing in high or medium poverty areas compared to low poverty areas.

RESULTS

High poverty areas tended to have a greater prevalence of HR-negative tumors compared to more affluent areas. Although not always significant, this was observed among non-Hispanic white and Hispanic women regardless of age-tumor stage category, and only among young, non-Hispanic black women and non-Hispanic Asian/Pacific Islander women with regional and distant stage. High poverty areas also tended to have a greater prevalence of HR-unknown tumors compared to more affluent areas. Furthermore, significant trends between HR status and poverty level varied by race/ethnicity, age, and tumor stage.

CONCLUSIONS

Poverty may be related to breast cancer negative and unknown HR status. These findings suggest the effects of non-genetic factors on biochemical features of breast cancer, as well as imply a clinical importance to improve HR measurement or recording for low socioeconomic breast cancer patients.

Carotenoid intakes and risk of breast cancer defined by estrogen receptor and progesterone receptor status: a pooled analysis of 18 prospective cohort studies

BACKGROUND

Epidemiologic studies examining associations between carotenoid intakes and risk of breast cancer by estrogen receptor (ER) and progesterone receptor (PR) status are limited.

OBJECTIVE

We investigated these associations in a pooled analysis of 18 cohort studies.

DESIGN

Of 1,028,438 participants followed for a maximum follow-up of 26 y across studies, 33,380 incident invasive breast cancers were identified. Study-specific RRs and 95% CIs were estimated by using Cox proportional hazards regression and then pooled by using a random-effects model.

RESULTS

α-Carotene, β-carotene, and lutein/zeaxanthin intakes were inversely associated with the risk of ER-negative (ER-) breast cancer (pooled multivariable RRs of the comparison between the highest and lowest quintiles): α-carotene (0.87; 95% CI: 0.78, 0.97), β-carotene (0.84; 95% CI: 0.77, 0.93), and lutein/zeaxanthin (0.87; 95% CI: 0.79, 0.95). These variables were not inversely associated with the risk of ER-positive (ER+) breast cancer (pooled multivariable RRs for the same comparison): α-carotene (1.04; 95% CI: 0.99, 1.09), β-carotene (1.04; 95% CI: 0.98, 1.10), and lutein/zeaxanthin (1.00; 95% CI: 0.93, 1.07). Although the pooled RRs for quintile 5 for β-cryptoxanthin were not significant, inverse trends were observed for ER- and ER+ breast cancer (P-trend ≤ 0.05). Nonsignificant associations were observed for lycopene intake. The associations were largely not appreciably modified by several breast cancer risk factors. Nonsignificant associations were observed for PR-positive and PR-negative breast cancer.

CONCLUSIONS

Intakes of α-carotene, β-carotene, and lutein/zeaxanthin were inversely associated with risk of ER-, but not ER+, breast cancer. However, the results need to be interpreted with caution because it is unclear whether the observed association is real or due to other constituents in the same food sources.

SIRT1 is essential for oncogenic signaling by estrogen/estrogen receptor α in breast cancer

The NAD-dependent histone deacetylase silent information regulator 1 (SIRT1) is overexpressed and catalytically activated in a number of human cancers, but recent studies have actually suggested that it may function as a tumor suppressor and metastasis inhibitor in vivo. In breast cancer, SIRT1 stabilization has been suggested to contribute to the oncogenic potential of the estrogen receptor α (ERα), but SIRT1 activity has also been associated with ERα deacetylation and inactivation. In this study, we show that SIRT1 is critical for estrogen to promote breast cancer. ERα physically interacted and functionally cooperated with SIRT1 in breast cancer cells. ERα also bound to the promoter for SIRT1 and increased its transcription. SIRT1 expression induced by ERα was sufficient to activate antioxidant and prosurvival genes in breast cancer cells, such as catalase and glutathione peroxidase, and to inactivate tumor suppressor genes such as cyclin G2 (CCNG2) and p53. Moreover, SIRT1 inactivation eliminated estrogen/ERα-induced cell growth and tumor development, triggering apoptosis. Taken together, these results indicated that SIRT1 is required for estrogen-induced breast cancer growth. Our findings imply that the combination of SIRT1 inhibitors and antiestrogen compounds may offer more effective treatment strategies for breast cancer.

Smoking and alcohol consumption in relation to risk of triple-negative breast cancer in a cohort of postmenopausal women

PURPOSE

Little is known about the risk factors for triple-negative breast cancer (TNBC), which has a worse prognosis compared to hormone receptor-positive breast cancer. We examined the association of smoking and alcohol intake with TNBC and estrogen receptor-positive (ER+) breast cancer.

METHODS

Among 148,030 women enrolled in the Women's Health Initiative, 300 TNBC cases and 2,479 ER+ cases were identified over a median of 8.0 years of follow-up. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI).

RESULTS

Cigarette smoking was not associated with TNBC, whereas drinkers had reduced risk compared to never drinkers. In contrast, both exposures showed slight positive associations with ER+ breast cancer: for women with ≥ 40 pack-years of smoking, the HR was 1.24, 95% CI 1.06-1.44; for women consuming ≥ 7 servings of alcohol per week, the HR was 1.26, 95% CI 1.06-1.50. Intakes of wine and hard liquor were also significantly positively associated with ER+ breast cancer.

CONCLUSIONS

These findings from a large cohort of postmenopausal women suggest that smoking and alcohol consumption are not associated with increased risk of TNBC, but may be modestly associated with increased risk of ER+ breast cancer.

Association of active and passive smoking with risk of breast cancer among postmenopausal women: a prospective cohort study

OBJECTIVE

To examine the association between smoking and risk of invasive breast cancer using quantitative measures of lifetime passive and active smoking exposure among postmenopausal women.

DESIGN

Prospective cohort study.

SETTING

40 clinical centres in the United States.

PARTICIPANTS

79,990 women aged 50-79 enrolled in the Women's Health Initiative Observational Study during 1993-8.

MAIN OUTCOME MEASURES

Self reported active and passive smoking, pathologically confirmed invasive breast cancer.

RESULTS

In total, 3520 incident cases of invasive breast cancer were identified during an average of 10.3 years of follow-up. Compared with women who had never smoked, breast cancer risk was elevated by 9% among former smokers (hazard ratio 1.09 (95% CI 1.02 to 1.17)) and by 16% among current smokers (hazard ratio 1.16 (1.00 to 1.34)). Significantly higher breast cancer risk was observed in active smokers with high intensity and duration of smoking, as well as with initiation of smoking in the teenage years. The highest breast cancer risk was found among women who had smoked for ≥ 50 years or more (hazard ratio 1.35 (1.03 to 1.77) compared with all lifetime non-smokers, hazard ratio 1.45 (1.06 to 1.98) compared with lifetime non-smokers with no exposure to passive smoking). An increased risk of breast cancer persisted for up to 20 years after smoking cessation. Among women who had never smoked, after adjustment for potential confounders, those with the most extensive exposure to passive smoking (≥ 10 years' exposure in childhood, ≥ 20 years' exposure as an adult at home, and ≥ 10 years' exposure as an adult at work) had a 32% excess risk of breast cancer compared with those who had never been exposed to passive smoking (hazard ratio 1.32 (1.04 to 1.67)). However, there was no significant association in the other groups with lower exposure and no clear dose response to cumulative passive smoking exposure.

CONCLUSIONS

Active smoking was associated with an increase in breast cancer risk among postmenopausal women. There was also a suggestion of an association between passive smoking and increased risk of breast cancer.

Oral contraceptive use and estrogen/progesterone receptor-negative breast cancer among African American women

BACKGROUND

Oral contraceptive formulations have changed over time, making it relevant to assess the effect of more recent formulations on breast cancer risk. In addition, some studies have found stronger positive associations of oral contraceptive use with estrogen receptor-negative (ER(-)) than with ER-positive (ER(+)) breast cancer. We carried out the first assessment of the effect of oral contraceptive use on the incidence of breast cancer classified by receptor status among African American women, a group disproportionately affected by ER(-) cancer.

METHODS

We followed 53,848 Black Women's Health Study participants from 1995 to 2007 through biennial health questionnaires, in which participants reported information about incident breast cancer, oral contraceptive use, and breast cancer risk factors. Pathology information was obtained on receptor status for 789 incident cases. Incidence rate ratios (IRR) with 95% confidence intervals (95% CI) were derived from Cox regression models with control for confounding factors.

RESULTS

Ever use of oral contraceptives was more strongly associated with ER(-)PR(-) breast cancer (279 cases; IRR, 1.65; 95% CI, 1.19-2.30) than with ER(+)PR(+) cancer (386 cases; IRR, 1.11; 95% CI, 0.86-1.42). The risk of ER(-)PR(-) breast cancer increased with increasing duration of use among recent users.

CONCLUSIONS

These results indicate that the oral contraceptive formulations used in recent decades increase breast cancer risk in African American women, with a greater effect for ER(-) than ER(+) cancer.

IMPACT

Mechanisms to explain the adverse influence of oral contraceptive use on ER(-) breast cancer need to be elucidated.

Risk factors according to estrogen receptor status of breast cancer patients in Trivandrum, South India

Estrogen receptor (ER) status is an important biomarker in defining subtypes of breast cancer differing in antihormonal therapy response, risk factors and prognosis. However, little is known about association of ER status with various risk factors in the developing world. Our case-control study done in Kerala, India looked at the associations of ER status and risk factors of breast cancer. From 2002 to 2005, 1,208 cases and controls were selected at the Regional Cancer Center (RCC), Trivandrum, Kerala, India. Information was collected using a standardized questionnaire, and 3-way analyses compared ER+/ER- cases, ER+ cases/controls and ER- cases/controls using unconditional logistic regression to calculate odds ratios and 95% confidence intervals. The proportion of ER- cases was higher (64.1%) than ER+ cases. Muslim women were more likely to have ER- breast cancer compared to Hindus (OR = 1.48, 95% CI = 1.09, 2.02), an effect limited to premenopausal group (OR = 1.87, 95% CI = 1.26, 2.77). Women with higher socioeconomic status were more likely to have ER+ breast cancer (OR = 1.48, 95% CI = 1.11, 1.98). Increasing BMI increased likelihood of ER- breast cancer in premenopausal women (p for trend < 0.001). Increasing age of marriage was positively associated with both ER+ and ER- breast cancer. Increased breastfeeding and physical activity were in general protective for both ER+ and ER- breast cancer. The findings of our study are significant in further understanding the relationship of ER status and risk factors of breast cancer in the context of the Indian subcontinent.

CD24 expression has a prognostic impact in breast carcinoma

We investigated the prognostic significance of BAG-1 and CD24 in invasive breast carcinomas. Seventy cases of invasive breast carcinoma were studied immunocytochemically for the expression of BAG-1 and CD24. The results were correlated with several prognostic parameters, including 5-year survival. Univariate analysis showed a significant correlation of BAG-1 and CD24 overall positive staining with several adverse prognostic parameters, such as increased stage (p<0.0001), tumor grade 3 (p=0.016 and p=0.02, respectively), positive lymph nodes (p<0.0001), and increased tumor size (p<0.0001). Similar results were found for BAG-1 nuclear staining, as well as for positive cytoplasmic CD24 expression. Both of our markers studied had a significant, negative effect on survival. Multivariate analysis further revealed an independent prognostic impact for CD24 overall staining. The results of our study showed that overall cytoplasmic and especially nuclear BAG-1 expression, as well as overall and cytoplasmic CD24 expression, correlates with adverse prognostic parameters. An independent prognostic value for overall CD24 staining was also demonstrated.

A case-control study of oral contraceptive use and incident breast cancer

Oral contraceptive (OC) use has been linked to increased risk of breast cancer, largely on the basis of studies conducted before 1990. In the Case-Control Surveillance Study, a US hospital-based case-control study of medication use and cancer, the authors assessed the relation of OC use to breast cancer risk among 907 case women with incident invasive breast cancer (731 white, 176 black) and 1,711 controls (1,152 white, 559 black) interviewed from 1993 to 2007. They evaluated whether the association differed by ethnicity or tumor hormone receptor status. After control for breast cancer risk factors, the multivariable odds ratio for 1 year or more of OC use, relative to less than 1 year of use, was 1.5 (95% confidence interval: 1.2, 1.8). The estimates were similar within age strata (<50 years and >or= 50 years). The odds ratios were larger for use within the previous 10 years, long-duration use, and black ethnicity, but these differences were not statistically significant. The association of OC use with breast cancer risk did not differ according to the estrogen or progestogen receptor status of the tumor. These results suggest that OC use is associated with an increased risk of breast cancer diagnosed in recent years.

Body weight and incidence of breast cancer defined by estrogen and progesterone receptor status--a meta-analysis

Epidemiological evidence indicates that the association between body weight and breast cancer risk may differ across menopausal status as well as the estrogen receptor (ER) and progesterone receptor (PR) tumor status. To date, no meta-analysis has been conducted to assess the association between body weight and ER/PR defined breast cancer risk, taking into account menopausal status and study design. We searched MEDLINE for relevant studies published from January 1, 1970 through December 31, 2007. Summarized risk estimates with 95% confidence intervals (CIs) were calculated using a random-effects model. The summarized results of 9 cohorts and 22 case-control studies comparing the highest versus the reference categories of relative body weight showed that the risk for ER+PR+ tumors was 20% lower (95% CI=-30% to -8%) among premenopausal (2,643 cases) and 82% higher (95% CI=55-114%) among postmenopausal (5,469 cases) women. The dose-response meta-analysis of ER+PR+ tumors showed that each 5-unit increase in body mass index (BMI, kg/m2) was associated with a 33% increased risk among postmenopausal women (95% CI=20-48%) and 10% decreased risk among premenopausal women (95% CI=-18% to -1%). No associations were observed for ER-PR- or ER+PR- tumors. For discordant tumors ER+PR- (pre) and ER-PR+ (pre/post) the number of cases were too small (<200) to interpret results. The relation between body weight and breast cancer risk is critically dependent on the tumor's ER/PR status and the woman's menopausal status. Body weight control is the effective strategy for preventing ER+PR+ tumors after menopause.

Population-based estimates of the relation between breast cancer risk, tumor subtype, and family history

OBJECTIVE

Many studies that have estimated the breast cancer risk attributable to family history have been based on data collected within family units. Use of this study design has likely overestimated risks for the general population. We provide population-based estimates of breast cancer risk and different tumor subtypes in relation to the degree, number, and age at diagnosis of affected relatives.

METHODS

Cox Proportional Hazards to calculate risks (hazard ratios; 95% confidence interval) of breast cancer and tumor subtypes for women with a family history of breast cancer relative to women without a family history among a cohort of 75,189 women age >or=40 years of whom 1,087 were diagnosed with breast cancer from June 1, 2001-December 31, 2005 (median follow-up 3.16 years).

RESULTS

Breast cancer risk was highest for women with a first-degree family history (1.54; 1.34-1.77); and did not differ substantially by the affected relative's age at diagnosis or by number of affected first-degree relatives. A second-degree family history only was not associated with a significantly increased breast cancer risk (1.15; 0.98-1.35). There was a suggestion that a positive family history was associated with risk of triple positive (Estrogen+/Progesterone+/HER2+) and HER2-overexpressing tumors.

CONCLUSIONS

While a family history of breast cancer in first-degree relatives is an important risk factor for breast cancer, gathering information such as the age at diagnosis of affected relatives or information on second-degree relative history may be unnecessary in assessing personal breast cancer risk among women age >or=40 years.

Use of different postmenopausal hormone therapies and risk of histology- and hormone receptor-defined invasive breast cancer

PURPOSE

We previously found that the risk of invasive breast cancer varied according to the progestagen component of combined postmenopausal hormone therapy (CHT): progesterone, dydrogesterone, or other progestagens. We conducted the present study to assess how these CHTs were associated with histology- and hormone receptor-defined breast cancer.

PATIENTS AND METHODS

We used data from the French E3N cohort study, with 80,391 postmenopausal women followed for a mean duration of 8.1 years; 2,265 histologically confirmed invasive breast cancers were identified through biennial self-administered questionnaires completed from 1990 to 2002. The relative risks (RRs) were estimated using Cox proportional hazards models.

RESULTS

Compared with postmenopausal hormone therapy (HT) never-use, ever-use of estrogen+progesterone was not significantly associated with the risk of any breast cancer subtype, but increasing duration of estrogen+progesterone was associated with increasing risks of lobular (P = .06) and estrogen receptor-positive/progesterone receptor-negative (ER+/PR-; P = .02). Estrogen+dydrogesterone was associated with a significant increase in risk of lobular carcinoma (RR, 1.7; 95% CI, 1.1 to 2.6). Estrogen+other progestagens was associated with significant increases in risk of ductal and lobular carcinomas (RR, 1.6; 95% CI, 1.3 to 1.8; and 2.0; 95% CI, 1.5 to 2.7, respectively), of ER+/PR+ and ER+/PR- carcinomas (RR, 1.8; 95% CI, 1.5 to 2.1; and 2.6; 95% CI, 1.9 to 3.5, respectively), but not of ER-/PR+ or ER-/PR- carcinomas (RR, 1.0; 95% CI, 0.5 to 2.1; and 1.4; 95% CI, 0.9 to 2.0, respectively).

CONCLUSION

The increase in risk of breast cancer observed with the use of CHTs other than estrogen+progesterone and estrogen+dydrogesterone seems to apply preferentially to ER+ carcinomas, especially those ER+/PR-, and to affect both ductal and lobular carcinomas.

Risk factors and hormone-receptor status: epidemiology, risk-prediction models and treatment implications for breast cancer

It is increasingly being recognized that breast cancer does not represent a single homogeneous disease; instead, the hormone-receptor status defines important clinical and etiologic differences. We review the epidemiologic data on differences in risk-factor associations by hormone-receptor status and highlight major trends in the literature. We discuss the development and evaluation of breast cancer risk models, with a focus on the Rosner and Colditz model, which can separately estimate the risk of hormone-receptor-positive and hormone-receptor-negative breast cancers. We also discuss the clinical implications of accounting for hormone-receptor status in breast cancer risk-prediction models.

Risk factors for hormone receptor-defined breast cancer in postmenopausal women

The effect of classic breast cancer risk factors on hormone receptor-defined breast cancer is not fully clarified. We explored these associations in a Swedish population-based study. Postmenopausal women ages 50 to 74 years, diagnosed with invasive breast cancer during 1993 to 1995, were compared with 3,065 age frequency-matched controls. We identified 332 estrogen receptor (ER-) and progesterone receptor (PR-) negative, 286 ER+PR-, 71 ER-PR+, 1,165 ER+PR+, and 789 tumors with unknown receptor status. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Women ages >or=30 years, compared with those ages 20 to 24 years at first birth, were at an increased risk of ER+PR+ tumors (OR, 1.5; 95% CI, 1.2-1.8) but not ER-PR- tumors (OR, 1.1; 95% CI, 0.8-1.6). Women who gained >or=30 kg in weight during adulthood had an approximately 3-fold increased relative risk of ER+PR+ tumors (OR, 2.7; 95% CI, 1.9-3.8), but no risk increase of ER-PR- tumors (OR, 1.0; 95% CI, 0.5-2.1), compared with women who gained <10 kg. Compared with never users, women who used menopausal estrogen-progestin therapy for at least 5 years were at increased risk of ER+PR+ tumors (OR, 3.0; 95% CI, 2.1-4.1) but not ER-PR- tumors (OR, 1.3; 95% CI, 0.7-2.5). In conclusion, other risk factors were similarly related to breast cancer regardless of receptor status, but high age at first birth, substantial weight gain in adult age, and use of menopausal estrogen-progestin therapy were more strongly related to receptor-positive breast cancer than receptor-negative breast cancer.

Tobacco smoking, NAT2 acetylation genotype and breast cancer risk

The role of active and passive cigarette smoking in breast cancer etiology remains controversial. Using data from a large population-based case-control study in Poland (2386 cases, 2502 controls) conducted during 2000-2003, we examined the associations between active and passive smoking overall and for different age categories. We also evaluated differences in risk by estrogen receptor (ER) and progesterone receptor (PR) status in tumors, and the potential modification of the smoking association by N-acetyl transferase 2 (NAT2) genotype. Women ever exposed to passive smoking at home or at work had a risk of breast cancer similar to those never exposed to active or passive smoking (OR (95%CI) = 1.11 (0.85-1.46), and no trends were observed with increasing hours/day-years of passive smoking exposure. Active smoking was associated with a significant increase in risk only among women younger than 45 years of age (OR (95%CI) = 1.95 (1.38-2.76); 1.15 (0.93-1.40); 0.91 (0.77-1.09) for < 45, 45-55 and > 55 years of age, respectively; p-heterogeneity < 0.001 for < 45 vs. > 55 years) and prevailed for both ER+ and ER- tumors. The smoking association among women < 45 years was stronger for current than former smokers, and a significant trend was observed with duration of smoking (p = 0.04). NAT2 slow vs. rapid/intermediate acetylation genotype was not related to breast cancer risk (0.99 (0.87-1.13)), and did not significantly modify the smoking relationships. In conclusion, our data indicate that passive smoking is not associated with breast cancer risk; however, active smoking might be associated with an increased risk for early onset breast cancers.

Body weight and postmenopausal breast cancer risk defined by estrogen and progesterone receptor status among Swedish women: A prospective cohort study

Although obesity is one of the established risk factors for postmenopausal breast cancer, it is not clear whether this positive association differs across estrogen receptor (ER) and progesterone receptor (PR) status of breast tumors. We evaluated the association between body weight and ER/PR defined breast cancer risk stratified by postmenopausal hormone (PMH) use and a family history of breast cancer in the population-based Swedish Mammography Screening Cohort comprising 51,823 postmenopausal women. Relative body weight was measured by body mass index (kg/m2) based on self-reported weight and height collected in 1987 and 1997. Relative risks (RRs) were estimated by hazard ratios derived from Cox proportional hazards regression models. During an average of 8.3-year follow-up, 1,188 invasive breast cancer cases with known ER and PR status were diagnosed. When comparing to normal weight group, we observed a positive association between obesity and risk for the development of ER+ PR+ tumors (RR = 1.67, 95% CI = 1.34-2.07) and an inverse association for the development of all PR- tumors (RR = 0.68, 95% CI = 0.47-0.98). Statistically significant heterogeneity was observed in the RRs between ER+ PR+ tumors and all PR- tumors (p(heterogeneity) < 0.0001). The positive association of obesity with the development of ER+ PR+ tumors was confined to never-users of PMHs (RR = 1.90 (CI 95%:1.38-2.61)) and to those without a family history of breast cancer (RR = 1.82 (CI 95%:1.45-2.29)). Our results support the hypothesis that excess endogenous estrogen due to obesity contributes to an increased risk of ER+ PR+ postmenopausal breast cancer.

What can be learnt from models of incidence rates?

Models of breast cancer incidence have evolved from the observation by Armitage and Doll in the 1950s that the pattern of incidence by age differs for reproductive cancers from those of other major malignancies. Both two-stage and multistage models have been applied to breast cancer incidence. Consistent across modeling approaches, risk accumulation or the rate of increase in breast cancer incidence is most rapid from menarche to first birth. Models that account for the change in risk after menopause and the temporal sequence of reproductive events summarize risk efficiently and give added insights to potentially important mechanistic features. First pregnancy has an adverse impact on progesterone receptor negative tumors, while increasing parity reduces the risk of estrogen/progesterone receptor positive tumors but not estrogen/progesterone receptor negative tumors. Integrated prediction models that incorporate prediction of carrier status for highly penetrant genes and also account for lifestyle factors, mammographic density, and endogenous hormone levels remain to be efficiently implemented. Models that both inform and reflect the emerging understanding of the molecular and cell biology of carcinogenesis are still a long way off.

Alcohol and postmenopausal breast cancer risk defined by estrogen and progesterone receptor status: a prospective cohort study

BACKGROUND

Alcohol intake has been reported to be positively associated with an increased risk of postmenopausal breast cancer; however, the association with the estrogen receptor (ER) and progesterone receptor (PR) status of the breast tumors remains unclear.

METHODS

Self-reported data on alcohol consumption were collected in 1987 and 1997 from 51,847 postmenopausal women in the population-based Swedish Mammography Cohort. Through June 30, 2004, 1188 invasive breast cancer case patients with known ER and PR status were identified during an average 8.3-year follow-up. We used Cox proportional hazards models to estimate multivariable relative risks (RRs) of breast cancer, adjusting for age; family history of breast cancer; body mass index; height; parity; age at menarche, first birth, and menopause; education level; use of postmenopausal hormones; and diet. Heterogeneity among groups was evaluated using the Wald test. All statistical tests were two-sided.

RESULTS

Alcohol consumption was associated with an increased risk for the development of ER-positive (+) tumors, irrespective of PR status (highest intake [> or = 10 g of alcohol per day] versus nondrinkers, multivariable RR = 1.35, 95% confidence interval [CI] = 1.02 to 1.80; Ptrend < .049 for ER+PR+ tumors; and RR = 2.36, 95% CI = 1.56 to 3.56; Ptrend < .001 for ER+PR-tumors). The absolute rate of ER+ breast cancer (standardized to the age distribution of person-years experienced by all study participants using 5-year age categories) was 232 per 100,000 person-years among women in the highest category of alcohol intake, and 158 per 100,000 person-years among nondrinkers. No association was observed between alcohol intake and the risk of developing ER-tumors. Furthermore, we observed a statistically significant interaction between alcohol intake and the use of postmenopausal hormones on the risk for ER+PR+ tumors (Pinteraction = .039).

CONCLUSION

The observed association between risk of developing postmenopausal ER+ breast cancer and alcohol drinking, especially among those women who use postmenopausal hormones, may be important, because the majority of breast tumors among postmenopausal women overexpress ER.

Effect of dietary intake of phytoestrogens on estrogen receptor status in premenopausal women with breast cancer

Although many dietary studies have focused on breast cancer risk, few have examined dietary influence on tumor characteristics such as estrogen receptor (ER) status. Because phytoestrogens may modulate hormone levels and ER expression, we analyzed ER status and phytoestrogen intake in a case-case study of 124 premenopausal breast cancer patients. We assessed intake with a food-frequency questionnaire and obtained ER status from medical records. Rather than focusing on risk, we evaluated whether low intakes were more strongly associated with ER-negative tumors than with ER-positive disease. In logistic regression adjusting for potential confounders, threefold greater risks of ER-negative tumors relative to ER-positive tumors were associated with low intake of the isoflavones genistein (odds ratio, OR=3.50; 95% confidence interval, CI=1.43-8.58) and daidzein (OR=3.10; 95% CI=1.31-7.30). Low intake of the flavonoid kaempferol (OR=0.36; 95% CI=0.16-0.83), the trace element boron (OR=0.33; 95% CI=0.13-0.83), and the phytosterol beta-sitosterol (OR=0.42; 95% CI=0.18-0.98) were associated with decreased risk of ER-negative tumors relative to ER-positive disease. Other phytoestrogens were not significantly associated with ER status. Thus, in premenopausal patients, some phytoestrogens may affect breast carcinogenesis by influencing ER status. Such findings suggest new directions for mechanistic research on dietary factors in breast carcinogenesis that may have relevance for prevention and clinical treatment.

The joint effect of smoking and AIB1 on breast cancer risk in BRCA1 mutation carriers

Women with BRCA1 mutations are at an elevated risk for breast cancer. AIB1 (NCOA3/SRC3) genotype and smoking may alter this risk. We examined the differences in breast cancer risk by AIB1 polyglutamine repeat polymorphism and pre-diagnosis smoking habits for BRCA1 mutation carriers to determine if there was an interaction between smoking and AIB1 genotype. Multivariate Cox proportional hazards regression was used with 316 female BRCA1 mutation carriers to model breast cancer risk. Ever having smoked was associated with a decreased breast cancer risk [Hazard Ratio (HR) = 0.63, 95% CI, 0.47-0.87]. A dose-response relationship between number of pack-years smoked and breast cancer risk was also found for women who smoked <20 pack years of cigarettes (HR = 0.72, 95% CI, 0.52-1.00) and for women who smoked >/=20 pack years (HR = 0.41, 95% CI, 0.23-0.71; P for trend = 0.0007). Women with a 28 repeat allele for AIB1 had a significantly reduced risk of breast cancer (HR = 0.72, 95% CI, 0.51-1.00). Women who smoked >/=20 pack-years with a 28 repeat allele had an even greater reduced risk of breast cancer (HR = 0.19, 95% CI, 0.07-0.54) compared to women who were never smokers with no 28 allele. Since AIB1 appears to modulate the effect of endogenous hormones via the estrogen receptor, and smoking affects circulating hormone levels, these results support evidence that steroid hormones play an important role in breast carcinogenesis in BRCA1 mutation carriers, and suggest mechanisms for developing novel cancer prevention strategies for BRCA1 mutation carriers.

Reproductive factors and subtypes of breast cancer defined by hormone receptor and histology

Reproductive factors are associated with reduced risk of breast cancer, but less is known about whether there is differential protection against subtypes of breast cancer. Assuming reproductive factors act through hormonal mechanisms they should protect predominantly against cancers expressing oestrogen (ER) and progesterone (PR) receptors. We examined the effect of reproductive factors on subgroups of tumours defined by hormone receptor status as well as histology using data from the NIHCD Women's Contraceptive and Reproductive Experiences (CARE) Study, a multicenter case–control study of breast cancer. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) as measures of relative risk using multivariate unconditional logistic regression methods. Multiparity and early age at first birth were associated with reduced relative risk of ER + PR + tumours (P for trend=0.0001 and 0.01, respectively), but not of ER − PR − tumours (P for trend=0.27 and 0.85), whereas duration of breastfeeding was associated with lower relative risk of both receptor-positive (P for trend=0.0002) and receptor-negative tumours (P=0.0004). Our results were consistent across subgroups of women based on age and ethnicity. We found few significant differences by histologic subtype, although the strongest protective effect of multiparity was seen for mixed ductolobular tumours. Our results indicate that parity and age at first birth are associated with reduced risk of receptor-positive tumours only, while lactation is associated with reduced risk of both receptor-positive and -negative tumours. This suggests that parity and lactation act through different mechanisms. This study also suggests that reproductive factors have similar protective effects on breast tumours of lobular and ductal origin.

Immunoreactive estrogen receptor in breast tumor and adjacent tissue: association with clinicopathological characteristics in Indian population

BACKGROUND AND OBJECTIVES

Estrogen receptor (ER) status serves as an important prognostic marker in the management of breast cancer. The level of ER in breast tumor is different in different racial and ethnic groups. In the present study, we have compared the ER levels in breast tumor and adjacent normal tissue in Indian sub-population.

METHODS

Immunoreactive ER was measured by enzyme immunoassay in breast tumors (ERt) and adjacent area (ERa) derived from 45 breast cancer patients from North India. Clinical parameters like age, menopausal status, tumor stage, recurrence and treatment status were recorded.

RESULTS

A significant positive correlation was observed between the levels of ERt and ERa (r = 0.386, P = 0.009). While the ERt levels increased with advancing age (P = 0.087), the ERa levels did not change in different age groups. The ERt levels negatively correlated with tumor stage and recurrence (r = -0.263, P = 0.110 and r = -0.202, P = 0.189). A significant negative correlation was also observed between the ERa levels and tumor recurrence (r = -0.337, P = 0.025). Further, the ERt positivity was higher than the ERa positivity. The clinical characteristics like age, tumor stage, metastasis, recurrence, and treatment status did not correlate with ERt and ERa positivity.

CONCLUSIONS

The present study shows that the levels of ERt and ERa positively correlate and both ERt and ERa show negative correlation with tumor recurrence.

Breast cancer risk factors according to joint estrogen receptor and progesterone receptor status

BACKGROUND

We investigated risk factor patterns for subtypes of breast cancer characterized by joint estrogen receptor (ER) and progesterone receptor (PR) status in a hospital-based case-control study.

METHODS

ER and PR tumor status were determined immunohisotchemically. Risk factors of interest were entered into a multiple polychotomous logistic regression model simultaneously; odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Using this model, cases in the four tumor subtypes (ER+PR+, ER-PR-, ER+PR-, ER-PR+) were compared simultaneously to controls. A Wald test for heterogeneity across the four subtypes was conducted, as well as a case-case comparison between the two most biologically disparate subtypes, ER+PR+ and ER-PR-.

RESULTS

The receptor status distribution was as follows: 33% ER+PR+, 34% ER-PR-, 20% ER+PR-, and 13% ER-PR+. Among 317 cases and 401 controls, we found significant heterogeneity across the four tumor subtypes for older age at first full-term pregnancy (p=0.04) and post-menopausal status (p=0.04). For older age at first full-term pregnancy, an elevated risk was found for the ER+PR- subtype (OR=2.5; 95% CI: 1.2-5.1). For post-menopausal status, elevated risks were found for both the ER+PR+ (OR=2.4; 95% CI: 1.1-4.9) and ER+PR- (OR=7.2; 95% CI: 2.4-21.7) subtypes. From the case-case comparisons, we found that cases, who had consumed alcohol for more than 1 year were 3.4 times more likely to have ER+PR+ tumors than ER-PR- tumors (95% CI: 1.4-8.4).

CONCLUSIONS

Certain breast cancer risk factors may vary by ER and PR status, and joint ER/PR status should be taken into account in future studies of risk factor estimates.

A Predictive Model for the Development of Hormone-Responsive Breast Cancer

BACKGROUND

Effective therapies to reduce the risk of hormone-sensitive breast cancers (ER or PR positive) exist. Available models predict the risk of breast cancer without addressing hormone receptor status. The purpose of this study was to identify risk factors predictive of the development of hormone-sensitive cancers.

METHODS

A total of 1285 invasive breast cancers in 1263 women were identified from a prospectively maintained database. Risk factors were compared for ER+ and ER- cancers by using Fisher's exact test.

RESULTS

Models were developed for premenopausal and postmenopausal women. In premenopausal women, white race, age at menarche < 12 years, and nulliparity or age at first birth > 20 years were used. The risk of ER+ cancer increased from 67.7% with 0 variables to 83.8% with all three (P = .013). In postmenopausal women, white race and a history of estrogen therapy were used. With none of the variables present, the incidence of ER+ cancer was 70.0%; it was 77.6% with one variable and 85.4% with both variables (P = .002). In postmenopausal women, variables predicted significant differences in hormone sensitivity only for those aged < or = 60 years. In the subset of women with information on alcohol use, adding this variable to the model improved the prediction of hormonal status.

CONCLUSIONS

Our findings, if prospectively validated, may help identify those who would obtain the greatest benefit from hormonal chemoprevention strategies for breast cancer risk reduction.

Etiology of Hormone Receptor–Defined Breast Cancer: A Systematic Review of the Literature

Breast cancers classified by estrogen receptor (ER) and/or progesterone receptor (PR) expression have different clinical, pathologic, and molecular features. We examined existing evidence from the epidemiologic literature as to whether breast cancers stratified by hormone receptor status are also etiologically distinct diseases. Despite limited statistical power and nonstandardized receptor assays, in aggregate, the critically evaluated studies (n = 31) suggest that the etiology of hormone receptor–defined breast cancers may be heterogeneous. Reproduction-related exposures tended to be associated with increased risk of ER-positive but not ER-negative tumors. Nulliparity and delayed childbearing were more consistently associated with increased cancer risk for ER-positive than ER-negative tumors, and early menarche was more consistently associated with ER-positive/PR-positive than ER-negative/PR-negative tumors. Postmenopausal obesity was also more consistently associated with increased risk of hormone receptor–positive than hormone receptor–negative tumors, possibly reflecting increased estrogen synthesis in adipose stores and greater bioavailability. Published data are insufficient to suggest that exogenous estrogen use (oral contraceptives or hormone replacement therapy) increase risk of hormone-sensitive tumors. Risks associated with breast-feeding, alcohol consumption, cigarette smoking, family history of breast cancer, or premenopausal obesity did not differ by receptor status. Large population-based studies of determinants of hormone receptor–defined breast cancers defined using state-of-the-art quantitative immunostaining methods are needed to clarify the role of ER/PR expression in breast cancer etiology.

Fruits, Vegetables, and Micronutrients in Relation to Breast Cancer Modified by Menopause and Hormone Receptor Status

Whether fruit, vegetable, and antioxidant micronutrient consumption is associated with a reduction in breast cancer incidence remains unresolved. To address this issue, we analyzed data from a large population-based case-control study, with consideration given to whether the associations varied with menopausal status or with clinical characteristics of the cases' disease. Study participants completed a modified Block food frequency questionnaire, which included assessment of the frequency and portion sizes of 13 fruits and fruit juices and 16 vegetables and the use of multiple and single vitamin supplements. Statistical analyses were done on 1,463 cases and 1,500 controls. Among postmenopausal women, reduced odds ratios [OR; 95% confidence intervals (95% CI)] were noted for the highest fifth, as compared with the lowest fifth, of intake of any vegetables [0.63 (0.46–0.86); P for trend &lt; 0.01] and leafy vegetables [0.66 (0.50–0.86); P for trend = 0.03] after controlling for age and energy intake. Adjusted ORs (95% CIs) were also decreased for postmenopausal breast cancer in relation to high intake of carotenoids, α-carotene, β-carotene, lutein, and particularly lycopene [0.66 (0.48–0.90); P for trend = 0.03]. Inverse associations for fruits and vegetables were stronger for postmenopausal women with estrogen receptor (ER)+ tumors (OR, 0.65; 95% CI, 0.51–0.82) than ER− tumors (OR, 0.92; 95% CI, 0.64–1.32), but results were less consistent for micronutrients. No similarly reduced associations were observed among premenopausal women. ORs did not appreciably differ by in situ or invasive breast cancer or by whether cases had begun chemotherapy. Our results support an inverse association for fruit and vegetable intake among postmenopausal but not premenopausal breast cancer, which may be more pronounced among women with ER+ tumors.

A Prospective Study of Smoking and Risk of Breast Cancer in Young Adult Women

Objective: To investigate the association between smoking and invasive breast cancers characterized by their estrogen receptor status in a large prospective study of mainly premenopausal women. Method: 112,844 women aged 25–42 years in 1989 were followed 10 years; questionnaire information on medical illnesses and risk factors was collected biennially and information on diet was collected in 1991 and 1995. During this period of follow-up (1,077,536 person-years), 1009 incident breast cancer cases were documented. Results: In the multivariate-adjusted models, smoking status was not significantly related to overall breast cancer risk: compared with never smokers, the relative risks (RRs) were 1.18 [95% confidence interval (CI) 1.02–1.36] for past smokers and 1.12 (95% CI 0.92–1.37) for current smokers. Increasing duration of smoking before the first pregnancy was associated with a greater risk of breast cancer, although little increase was seen in the highest category: compared with never smokers, RRs were 1.42 (95% CI 1.10–1.83) for 15–19 years of smoking and 1.10 (95% CI 0.80–1.52) for ≥20 years of smoking (P for trend = 0.01). Smoking was related most strongly to the risk of estrogen receptor-positive breast cancers. For women who had smoked for ≥20 years, the RR of estrogen receptor-positive cancer was 1.37 (95% CI 1.07–1.74) and the RR of estrogen receptor-negative cancer was 1.04 (95% CI 0.71–1.53). For smoking before age 15, the RRs were 1.49 (95% CI 1.03–2.17) for estrogen receptor-positive cancer and 1.19 (95% CI 0.69–2.08) for estrogen receptor-negative cancer. Conclusion: Our results suggest that longer duration of smoking may be related to the risk of estrogen receptor-positive breast cancer but possibly less so for estrogen receptor-negative breast cancer.

Risk factors for breast cancer according to estrogen and progesterone receptor status

BACKGROUND

Evaluations of epidemiologic risk factors in relation to breast cancer classified jointly by estrogen receptor (ER) and progesterone receptor (PR) status have been inconsistent. To address this issue, we conducted a prospective evaluation of risk factors for breast cancer classified according to receptor status.

METHODS

During 1 029 414 person-years of follow-up of 66 145 women participating in the Nurses' Health Study from 1980 through 2000, we identified 2096 incident cases of breast cancer for which information on ER/PR status was available: 1281 were ER+/PR+, 318 were ER+/PR-, 80 were ER-/PR+, and 417 were ER-/PR-. We fit a log-incidence model of breast cancer and used polychotomous logistic regression to compare coefficients for breast cancer risk factors in patients with different ER/PR status. To test for differences in risk factor odds ratios based on marginal ER/PR categories, we evaluated ER status controlling for PR status and vice versa. The predictive ability of our log-incidence model to discriminate between women who would develop ER+/PR+ breast cancer and those who would not (and similarly for ER-/PR- breast cancer) was evaluated by using receiver operator characteristic curve analysis. All statistical tests were two-sided.

RESULTS

We observed statistically significant heterogeneity among the four ER/PR categories for some risk factors (age, menopausal status, body mass index [BMI] after menopause, the one-time adverse effect of first pregnancy, and past use of postmenopausal hormones) but not for others (benign breast disease, family history of breast cancer, alcohol use, and height). The one-time adverse association of first pregnancy with incidence was present for PR- but not for PR+ tumors after controlling for ER status (P =.007). However, the association of BMI after menopause with incidence was present for PR+ but not PR- tumors (P =.005). Statistically significant differences in the incidence of ER+ and ER- tumors were seen with age, both before and after menopause (P =.003), and with past use of postmenopausal hormones (P =.01). Area under the receiver operator characteristic curve, adjusted for age, was 0.64 (95% confidence interval [CI] = 0.63 to 0.66) for ER+/PR+ tumors and 0.61 (95% CI = 0.58 to 0.64) for ER-/PR- tumors.

CONCLUSIONS

Incidence rates and risk factors for breast cancer differ according to ER and PR status. Thus, to accurately estimate breast cancer risk, breast cancer cases should be divided according to the ER and PR status of the tumor.