Established and Suspected Risk Factors in Breast Cancer Aetiology

Ambient fine particulate matter and breast cancer incidence in a large prospective US cohort

BACKGROUND

Fine particulate matter (PM2.5) has been inconsistently associated with breast cancer incidence, however, few studies have considered historic exposure when levels were higher.

METHODS

Outdoor residential PM2.5 concentrations were estimated using a nationwide spatiotemporal model for women in the National Institutes of Health-AARP Diet and Health Study, a prospective cohort located in 6 states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and 2 metropolitan areas (Atlanta, GA, and Detroit, MI) and enrolled in 1995-1996 (n = 196 905). Annual average PM2.5 concentrations were estimated for a 5-year historical period 10 years prior to enrollment (1980-1984). We used Cox regression to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between a 10 µg/m3 increase in PM2.5 and breast cancer incidence overall and by estrogen receptor status and catchment area.

RESULTS

With follow-up of participants through 2017, a total of 15 870 breast cancer cases were identified. A 10 ug/m3 increase in PM2.5 was statistically significantly associated with overall breast cancer incidence (HR = 1.08, 95% CI = 1.02 to 1.13). The association was evident for estrogen receptor-positive (HR = 1.10, 95% CI = 1.04 to 1.17) but not estrogen receptor-negative tumors (HR = 0.97, 95% CI = 0.84 to 1.13; Pheterogeneity = .3). Overall breast cancer hazard ratios were more than 1 across the catchment areas, ranging from a hazard ratio of 1.26 (95% CI = 0.96 to 1.64) for North Carolina to a hazard ratio of 1.04 (95% CI = 0.68 to 1.57) for Louisiana (Pheterogeneity = .9).

CONCLUSIONS

In this large US cohort with historical air pollutant exposure estimates, PM2.5 was associated with risk of estrogen receptor-positive breast cancer. State-specific estimates were imprecise but suggest that future work should consider region-specific associations and the potential contribution of PM2.5 chemical constituency in modifying the observed association.

Relationship between Health Inequalities and Breast Cancer Survival in Mexican Women

OBJECTIVE

We aimed to analyze the relationship between the survival of patients with breast cancer and health inequalities.

METHODS

A retrospective cohort study of women with stage III breast cancer according to public healthcare was conducted. Groups were stratified according to the course of treatment and the presence of chronic disease other than cancer. Survival functions were estimated by using the Kaplan-Meier estimator, while the Cox proportional hazards model was employed for prognostic assessment.

RESULTS

The study was performed on 964 breast cancer patients. One hundred and seventy-six patients (18.23%) died during the follow-up period and 788 (81.77%) were alive at the end of the follow-up period. Education, marital status, personal history of prior biopsies, and socioeconomic status (SES) were found to be linked with survival. However, only SES exceeded the baseline risk of mortality when the treatment cycle was interrupted (full treatment: unadjusted 4.683, p = 0.001; adjusted 4.888 p = 0.001, partial treatment: unadjusted 1.973, p = 0.012; adjusted 4.185, p = 0.001). The same effect was observed when stratifying by the presence of chronic disease other than cancer (with chronic disease adjusted HR = 4.948, p = 0.001; unadjusted HR = 3.303, p = 0.001; without chronic disease adjusted HR = 4.850, p = 0.001; unadjusted HR = 5.121, p = 0.001).

CONCLUSION

Since lower SES was linked with a worse prognosis, strategies to promote preventive medicine, particularly breast cancer screening programs and prompt diagnosis, are needed.

Correlation between oxidative stress markers and cytokines in different stages of breast cancer

This study aims to estimate the level of malondialdehyde (MDA) as oxidative stress marker and reduced glutathione (GSH) as antioxidant and correlate them to different inflammatory markers as interleukins (IL-6, IL-8, IL-10) and tumor necrosis factor alpha (TNF-α) in different stages of breast cancer (BC). For the purpose of comparisons, 35 healthy subjects matched for age, sex and ethnic background were selected who have no history or clinical evidence of BC or any chronic disease and obvious abnormalities as a control group and 35 patients of different stages of BC were participated in the study. The cancer patients were diagnosed by specialists. Even the exact cause of the disease has not been identified but according to this study, 5% of the patients were having family history of the disease and 62% of the patients were having a BMI over 25. Over 60% of the patients were postmenopausal and all females participated in this study were nonsmokers. MDA level showed a significant increase when BC patients were compared to healthy subjects, this oxidative stress marker showed a significant increase with the increase of the stage of the disease. In contrast the level of the lipid peroxide scavenger GSH reduced with increasing the stage of the disease. The level of some cytokines showed a significant change between different stages and the control group. Correlation between MDA and GSH with these cytokines showed a positive correlation between all cytokines and the MDA level and a negative correlation between GSH and the cytokines. The results of this study suggests that BC stimulates the oxidative stress response and for that, different inflammatory cytokines will be produced and there is a pronounced relationship between oxidative stress parameters and these cytokines and the level of these cytokines are associated with aggressive tumors.

Positive association between body height and breast cancer prevalence: a retrospective study with 135,741 women in Germany

Purpose

The aim of this study was to analyze the prevalence of breast cancer in relation to body height and to investigate associations between body height and breast cancer in Germany.

Methods

This retrospective cohort study included 135,741 adult women followed in one of 161 gynecology practices in Germany between January 2019 and December 2021. The 3 year prevalence of breast cancer (ICD-10: C50) during the study period was shown in relation to body height, which was included in this study as a five-category variable for women: ≤ 160 cm, 161–165 cm, 166–170 cm, 171–175 cm, > 175 cm. The associations between height and breast cancer were analyzed using logistic regression models adjusted for age and BMI.

Results

The prevalence of breast cancer increased from 5.1% in women ≤ 160 cm to 6.8% in women > 175 cm in the age group 51–60, and from 9.2% in women ≤ 160 cm to 12.2% in women 171–175 cm in the age group > 60 years. The OR for breast cancer was 1.18 (95% CI 1.12–1.24) for every 10 cm increase in height. Compared to height ≤ 160 cm, the OR for height 166–170 cm was 1.26 (1.15–1.39), for 171–175 cm 1.43 (1.27–1.61), and for > 175 cm 1.49 (1.28–1.74).

Conclusion

The results of this study suggest that greater body height in women is significantly related to an increased breast cancer risk.

LINE-1 methylation mediates the inverse association between body mass index and breast cancer risk: A pilot study in the Lebanese population

INTRODUCTION

Lebanon is among the top countries worldwide in combined incidence and mortality of breast cancer, which raises concern about risk factors peculiar to this country. The underlying molecular mechanisms of breast cancer require elucidation, particularly epigenetics, which is recognized as a molecular sensor to environmental exposures.

PURPOSE

We aim to explore whether DNA methylation levels of AHRR (marker of cigarette smoking), SLC1A5 and TXLNA (markers of alcohol consumption), and LINE-1 (a genome-wide repetitive retrotransposon) can act as molecular mediators underlying putative associations between breast cancer risk and pertinent extrinsic (tobacco smoking and alcohol consumption) and intrinsic factors [age and body mass index (BMI)].

METHODS

This is a cross-sectional pilot study which includes breast cancer cases (N = 65) and controls (N = 54). DNA methylation levels were measured using bisulfite pyrosequencing on available peripheral blood samples (N = 119), and Multivariate Imputation by Chained Equations (MICE) was used to impute missing DNA methylation values in remaining samples. Multiple mediation analysis was performed to assess direct and indirect (via DNA methylation) effects of intrinsic and extrinsic factors on breast cancer risk.

RESULTS

In relation to exposure, AHRR hypo-methylation was associated with cigarette but not waterpipe smoking, suggesting potentially different biomarkers of these two forms of tobacco use; SLC1A5 and TXLNA methylation were not associated with alcohol consumption; LINE-1 methylation was inversely associated with BMI (β-value [95% confidence interval (CI)] = -0.04 [-0.07, -0.02]), which remained significant after adjustment for age, smoking and alcohol consumption. In relation to breast cancer, there was no detectable association between AHRR, SLC1A5 or TXLNA methylation and cancer risk, but LINE-1 methylation was significantly higher in breast cancer cases when compared to controls (mean ± SD: 72.00 ± 0.66 versus 70.89 ± 0.73, P = 4.67 × 10-14). This difference remained significant after adjustment for confounders (odds ratio (OR) [95% CI] = 9.75[3.74, 25.39]). Moreover, LINE-1 hypo-methylation mediated 83% of the inverse effect of BMI on breast cancer risk.

CONCLUSION

This pilot study demonstrates that alterations in blood LINE-1 methylation mediate the inverse effect of BMI on breast cancer risk. This warrants large scale studies and stratification based on clinic-pathological types of breast cancer.

Gene-Environment Interactions Relevant to Estrogen and Risk of Breast Cancer: Can Gene-Environment Interactions Be Detected Only among Candidate SNPs from Genome-Wide Association Studies?

In this study we aim to examine gene-environment interactions (GxEs) between genes involved with estrogen metabolism and environmental factors related to estrogen exposure. GxE analyses were conducted with 1970 Korean breast cancer cases and 2052 controls in the case-control study, the Seoul Breast Cancer Study (SEBCS). A total of 11,555 SNPs from the 137 candidate genes were included in the GxE analyses with eight established environmental factors. A replication test was conducted by using an independent population from the Breast Cancer Association Consortium (BCAC), with 62,485 Europeans and 9047 Asians. The GxE tests were performed by using two-step methods in GxEScan software. Two interactions were found in the SEBCS. The first interaction was shown between rs13035764 of NCOA1 and age at menarche in the GE|2df model (p-2df = 1.2 × 10-3). The age at menarche before 14 years old was associated with the high risk of breast cancer, and the risk was higher when subjects had homozygous minor allele G. The second GxE was shown between rs851998 near ESR1 and height in the GE|2df model (p-2df = 1.1 × 10-4). Height taller than 160 cm was associated with a high risk of breast cancer, and the risk increased when the minor allele was added. The findings were not replicated in the BCAC. These results would suggest specificity in Koreans for breast cancer risk.

A Phenomic Perspective on Factors Influencing Breast Cancer Treatment: Integrating Aging and Lifestyle in Blood and Tissue Biomarker Profiling

Breast cancer is the most common malignancy among women worldwide. Over the last four decades, diagnostic and therapeutic procedures have improved substantially, giving patients with localized disease a better chance of cure, and those with more advanced cancer, longer periods of disease control and survival. However, understanding and managing heterogeneity in the clinical response exhibited by patients remains a challenge. For some treatments, biomarkers are available to inform therapeutic options, assess pathological response and predict clinical outcomes. Nevertheless, some measurements are not employed universally and lack sensitivity and specificity, which might be influenced by tissue-specific alterations associated with aging and lifestyle. The first part of this article summarizes available and emerging biomarkers for clinical use, such as measurements that can be made in tumor biopsies or blood samples, including so-called liquid biopsies. The second part of this article outlines underappreciated factors that could influence the interpretation of these clinical measurements and affect treatment outcomes. For example, it has been shown that both adiposity and physical activity can modify the characteristics of tumors and surrounding tissues. In addition, evidence shows that inflammaging and immunosenescence interact with treatment and clinical outcomes and could be considered prognostic and predictive factors independently. In summary, changes to blood and tissues that reflect aging and patient characteristics, including lifestyle, are not commonly considered clinically or in research, either for practical reasons or because the supporting evidence base is developing. Thus, an aim of this article is to encourage an integrative phenomic approach in oncology research and clinical management.

Association of breast cancer risk with polymorphisms in genes involved in the metabolism of xenobiotics and interaction with tobacco smoking: A gene-set analysis

Single nucleotide polymorphisms (SNPs) in genes involved in xenobiotics metabolism (XM) are suspected to play a role in breast cancer risk. However, previous findings based on a SNP by SNP approach need to be replicated taking into account the combined effects of multiple SNPs. We used a gene-set analysis method to study the association between breast cancer risk and genetic variation in XM genes (seen as a set of SNPs) and in the XM pathway (seen as a set of genes). We also studied the interaction between variants in XM genes and tobacco smoking. The analysis was conducted in a case-control study of 1,125 cases and 1,172 controls. Using a dedicated chip, genotyping data of 585 SNPs in 68 XM genes were available. Genetic variation in the whole XM pathway was significantly associated with premenopausal breast cancer risk (p = 0.008). This association was mainly driven by genetic variation in NAT2, CYP2C18, CYP2C19, AKR1C2 and ALDH1A3. The association between the XM gene pathway and breast cancer was observed among current and previous smokers, but not among never smokers (p = 0.013 for interaction between XM genes and tobacco smoking status). The association with breast cancer risk indicates that XM genes variants may play a role in breast carcinogenesis through their detoxification function of environmental pollutants, such as those contained in tobacco smoke.

PHLDA1 (pleckstrin homology-like domain, family A, member 1) knockdown promotes migration and invasion of MCF10A breast epithelial cells

PHLDA1 (pleckstrin homology-like domain, family A, member 1) is a multifunctional protein that plays distinct roles in several biological processes including cell death and therefore its altered expression has been identified in different types of cancer. Progressively loss of PHLDA1 was found in primary and metastatic melanoma while its overexpression was reported in intestinal and pancreatic tumors. Previous work from our group showed that negative expression of PHLDA1 protein was a strong predictor of poor prognosis for breast cancer disease. However, the function of PHLDA1 in mammary epithelial cells and the tumorigenic process of the breast is unclear. To dissect PHLDA1 role in human breast epithelial cells, we generated a clone of MCF10A cells with stable knockdown of PHLDA1 and performed functional studies. To achieve reduced PHLDA1 expression we used shRNA plasmid transfection and then changes in cell morphology and biological behavior were assessed. We found that PHLDA1 downregulation induced marked morphological alterations in MCF10A cells, such as changes in cell-to-cell adhesion pattern and cytoskeleton reorganization. Regarding cell behavior, MCF10A cells with reduced expression of PHLDA1 showed higher proliferative rate and migration ability in comparison with control cells. We also found that MCF10A cells with PHLDA1 knockdown acquired invasive properties, as evaluated by transwell Matrigel invasion assay and showed enhanced colony-forming ability and irregular growth in low attachment condition. Altogether, our results indicate that PHLDA1 downregulation in MCF10A cells leads to morphological changes and a more aggressive behavior.

Clinical Presentation and Frequency of Risk Factors in Patients with Breast Carcinoma in Pakistan

BACKGROUND

Breast cancer is known to be one of the most prevalent cancers among women in both developing and developed countries .The incidence of breast cancer in Pakistan has increased dramatically within the last few years and is the second country after Israel in Asia to have highest proportional cases of breast cancer. However, there are limited data for breast cancer available in the literature from Pakistan.

OBJECTIVES

The study was conducted to bring to light the common clinical presentation of breast cancer and to evaluate the frequency of established risk factors in breast carcinoma patients and furthermore to compare the findings between premenopausal and postmenopausal women in Pakistan.

MATERIALS AND METHODS

A 6 months (from July 2012 to Dec 2012) cross sectional survey was conducted in Surgical and Oncology Units of Civil Hospital, Karachi. Data were collected though a well developed questionnaire from 105 female patients diagnosed with carcinoma of breast and analyzed using SPSS version 17. Institutional ethical approval was obtained prior to data collection.

RESULTS

Out of 105 patients, 43 were premenopausal and 62 were postmenopausal, 99 being married. Mean age at diagnosis was 47.8 ± 12.4 years. A painless lump was the most frequent symptom, notived by 77.1%(n=81). Some 55.2% (n=58) patients had a lump in the right breast and 44.8%(n=47) in the left breast. In the majority of cases, the lump was present in upper outer quadrant 41.9% (n=44). Mean period of delay from appearance of symptoms to consulting a doctor was 5.13 ± 4.8 months, from the shortest 1 month to the longest 36 months. Long delay (> 3 months) was the most frequent figure 41.9%. Considering overall risk factors most frequent were first pregnancy after 20 years of age (41%), physical breast trauma (28.6%), lack of breast feeding(21.9%), and early menarche <11 years (19%), followed by null parity (16.2%), consumption of high fat diet (15.2%), family history of breast cancer or any other cancer in first degree relatives (9.5% and 13.3%, respectively). Some of the less common factors were late menopause >54 years (8.6%), use of oral contraceptive pills (10.5%), use of hormone replacement therapy (4.7%),smoking (4.7%) and radiation (0.96%). Significant differences (p<0.005) were observed between pre and post menopausal women regarding history of physical breast trauma, practice of breast feeding and parity.

CONCLUSIONS

A painless lump was the most frequent clinical presentation noted. Overall age at first child > 20 years, physical breast trauma, lack of breast feeding ,early menarche <11 were the most frequent risk factors. Physical breast trauma, lower parity, a trend for less breast feeding had more significant associations with pre-menopausal than post-menopausal onset. Increase opportunity of disease prevention can be obtained through better understanding of clinical presentation and risk factors important in the etiology of breast cancer.

Triiodothyronine and breast cancer

The thyroid hormones (THs), triiodothyronine (T3) and thyroxine (T4), are essential for survival; they are involved in the processes of development, growth, and metabolism. In addition to hyperthyroidism or hypothyroidism, THs are involved in other diseases. The role of THs in the development and differentiation of mammary epithelium is well established; however, their specific role in the pathogenesis of breast cancer (BC) is controversial. Steroid hormones affect many human cancers and the abnormal responsiveness of the mammary epithelial cells to estradiol (E2) in particular is known to be an important cause for the development and progression of BC. The proliferative effect of T3 has been demonstrated in various types of cancer. In BC cell lines, T3 may foster the conditions for tumor proliferation and increase the effect of cell proliferation by E2; thus, T3 may play a role in the development and progression of BC. Studies show that T3 has effects similar to E2 in BC cell lines. Despite controversy regarding the relationship between thyroid disturbances and the incidence of BC, studies show that thyroid status may influence the development of tumor, proliferation and metastasis.