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

ABSTRACT: 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.

SUBMITTER: Islami F

PROVIDER: S-EPMC4855244 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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

Islami F F Liu Y Y Jemal A A Zhou J J Weiderpass E E Colditz G G Boffetta P P Weiss M M

Annals of oncology : official journal of the European Society for Medical Oncology 20151026 12

<h4>Background</h4>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 recepto ...[more]

PMID: 26504151

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Project description:BackgroundIron has been shown to promote breast carcinogenesis in animal models through generation of oxidative stress and interaction with estrogen. Heme iron, which is found exclusively in animal-sourced foods, is suggested to have a more detrimental effect. Epidemiological evidence of the association between iron and breast cancer risk remains inconclusive and has not been comprehensively summarized. This systematic review and meta-analysis evaluated associations between both iron intake and body iron status and breast cancer risk.MethodsFour electronic databases (MEDLINE, EMBASE, CINAHL, and Scopus) were searched up to December 2018 for studies assessing iron intake and/or biomarkers of iron status in relation to breast cancer risk. Using random-effects meta-analyses, pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated comparing the highest vs. lowest category of each iron measure. Dose-response meta-analyses were also performed to investigate linear and nonlinear associations.ResultsA total of 27 studies were included in the review, of which 23 were eligible for meta-analysis of one or more iron intake/status measures. Comparing the highest vs. lowest category, heme iron intake was significantly associated with increased breast cancer risk, with a pooled RR of 1.12 (95% CI: 1.04-1.22), whereas no associations were found for dietary (1.01, 95% CI: 0.89-1.15), supplemental (1.02, 95% CI: 0.91-1.13), or total (0.97, 95% CI: 0.82-1.14) iron intake. Associations of iron status indicators with breast cancer risk were generally in the positive direction; however, a significant pooled RR was found only for serum/plasma levels (highest vs. lowest) of iron (1.22, 95% CI: 1.01-1.47), but not for ferritin (1.13, 95% CI: 0.78-1.62), transferrin saturation (1.16, 95% CI: 0.91-1.47), or total iron-binding capacity (1.10, 95% CI: 0.97-1.25). In addition, a nonlinear dose-response was observed for heme iron intake and serum iron (both Pnonlinearity < 0.05).ConclusionsHeme iron intake and serum iron levels may be positively associated with breast cancer risk. Although associations were modest, these findings may have public health implications given the widespread consumption of (heme) iron-rich foods. In light of methodological and research gaps identified, further research is warranted to better elucidate the relationship between iron and breast cancer risk.

Project description:BackgroundThe aim of this study was to quantitatively summarize the available evidence on the association of breastfeeding with the risk of childhood cancer.MethodsA literature search of PubMed and Embase databases was performed to identify eligible observational studies published from inception to July 17, 2020. The categorical and dose-response meta-analysis was conducted by pooling relative risk (RR) or odds ratio (OR) estimates with 95% confidence intervals (CIs). Potential sources of heterogeneity were detected by meta-regression and stratification analysis. Sensitivity analysis and publication bias test were also carried out.ResultsForty-five articles involving 475,579 individuals were included in the meta-analysis. Among the thirty-three studies on the association between breastfeeding and risk of childhood leukemia, the pooled risk estimates were 0.77 (95% CI, 0.65-0.91) and 0.77 (95% CI 0.63-0.94) for ever versus non/occasional breastfeeding and longest versus shortest breastfeeding duration group, respectively. There was clear indication for non-linear dose-response relationship between breastfeeding duration and the risk of childhood leukemia (P non-linear < 0.001). The most protective effect (OR, 0.66, 95% CI 0.62-0.70) was observed at a breastfeeding duration of 9.6 months. Four studies examined, the association between breastfeeding and risk of childhood neuroblastoma, and significant inverse associations were consistently observed in both the comparisons of ever breastfeeding versus non/occasional breastfeeding (OR = 0.59, 95% CI 0.44-0.81) and longest versus shortest breastfeeding (OR = 0.61, 95% CI 0.44-0.83). However, no associations of breastfeeding with risk of other cancers were found.ConclusionsOur study supports a protective role of breastfeeding on the risk of childhood leukemia, also suggesting a non-linear dose-response relationship. Further studies are warranted to confirm the association between breastfeeding and risk of childhood neuroblastoma.

Project description:BackgroundHuman epidermal growth factor receptor 2 (HER2)-low expression in breast cancer has been recently identified as a new therapeutic target. However, it is unclear if HER2-low status has an independent impact on prognosis.Materials and methodsA systematic literature research was carried out to identify studies comparing survival outcomes of patients affected by HER2-low versus HER2-zero breast cancer. Using random-effects models, pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for progression-free survival (PFS) and overall survival (OS) in the metastatic setting as well as disease-free survival (DFS), OS and pathological complete response (pCR) in the early setting. Subgroup analyses by hormone receptor (HoR) status were carried out. The study protocol is registered on PROSPERO (n.CRD42023390777).ResultsAmong 1916 identified records, 42 studies including 1 797 175 patients were eligible. In the early setting, HER2-low status was associated with significant improved DFS (HR 0.86, 95% CI 0.79-0.92, P < 0.001) and OS (HR 0.90, 95% CI 0.85-0.95, P < 0.001) when compared to HER2-zero status. Improved OS was observed for both HoR-positive and HoR-negative HER2-low populations, while DFS improvement was observed only in the HoR-positive subgroup. HER2-low status was significantly associated with a lower rate of pCR as compared to HER2-zero status both in the overall population (OR 0.74, 95% CI 0.62-0.88, P = 0.001) and in the HoR-positive subgroup (OR 0.77, 95% CI 0.65-0.90, P = 0.001). In the metastatic setting, patients with HER2-low breast cancers showed better OS when compared with those with HER2-zero tumours in the overall population (HR 0.94, 95% CI 0.89-0.98, P = 0.008), regardless of HoR status. No significant PFS differences were found.ConclusionsCompared with HER2-zero status, HER2-low status appears to be associated with a slightly increased OS both in the advanced and early settings, regardless of HoR expression. In the early setting, HER2-low tumours seem to be associated to lower pCR rates, especially if HoR-positive.

Project description:Objectives Mammographic density is a well-defined risk factor for breast cancer and having extremely dense breast tissue is associated with a one-to six-fold increased risk of breast cancer. However, it is questioned whether this increased risk estimate is applicable to current breast density classification methods. Therefore, the aim of this study was to further investigate and clarify the association between mammographic density and breast cancer risk based on current literature. Methods Medline, Embase and Web of Science were systematically searched for articles published since 2013, that used BI-RADS lexicon 5th edition and incorporated data on digital mammography. Crude and maximally confounder-adjusted data were pooled in odds ratios (ORs) using random-effects models. Heterogeneity regarding breast cancer risks were investigated using I2 statistic, stratified and sensitivity analyses. Results Nine observational studies were included. Having extremely dense breast tissue (BI-RADS density D) resulted in a 2.11-fold (95% CI 1.84–2.42) increased breast cancer risk compared to having scattered dense breast tissue (BI-RADS density B). Sensitivity analysis showed that when only using data that had adjusted for age and BMI, the breast cancer risk was 1.83-fold (95% CI 1.52–2.21) increased. Both results were statistically significant and homogenous. Conclusions Mammographic breast density BI-RADS D is associated with an approximately two-fold increased risk of breast cancer compared to having BI-RADS density B in general population women. This is a novel and lower risk estimate compared to previously reported and might be explained due to the use of digital mammography and BI-RADS lexicon 5th edition. Highlights • So far, breast density was linked to a one-to sixfold increased breast cancer risk.• Prior risk estimates were based on old BI-RADS lexicon and screen-film mammography.• We included only studies using digital mammography and BI-RADS lexicon 5th edition.• Breast density D is associated with a two-fold increased risk of breast cancer.• This is a lower risk estimate compared to previously reported studies.

Project description:BACKGROUND:Further research gaps exist in relation to the promotion of breastfeeding. Robust scientific evidence obtained by a meta-analysis would provide objectively summarized data while enabling the assessment of consistency of findings. This review includes the first documented meta-analysis done on the effectiveness of targeting fathers for promoting breastfeeding (BF). Assessments have been done for a primary outcome and for six more secondary outcomes. METHODS:PubMed, EMBASE, Google Scholar, CENTRAL databases and unpublished researches were searched. Selections of randomized-controlled trials and quasi-experimental studies were done in three rounds. Heterogeneity and potential publication bias were assessed. Eight studies were included in meta-analysis and others in narrative synthesis of the outcomes. Pooling was done with the Mental- Haenszel method using risk ratio (RR). Summary-of-Findings table was composed by Review-Manager (version 5.3) and GRADEproGDT applications. Subsequent sensitivity analysis was done. RESULTS:Selected eight interventional studies included 1852 families. Exclusive BF at six months was significantly higher (RR = 2.04, CI = 1.58-2.65) in the intervention groups. The RR at 4 months was 1.52 (CI = 1.14 to 2.03). Risk of full-formula-feeding (RR = 0.69, CI = 0.52-0.93) and the occurrence of lactation-related problems were lower in the intervention groups (RR = 0.24, CI = 0.10-0.57). More likelihood of rendering support in BF-related issues was seen in intervention groups (RR = 1.43, CI = 1.22-1.68). Increase of maternal knowledge and favorable attitudes on BF were higher in the intervention groups (P ≤; 0.001). The quality of evidence according to GRADE was "low" (for one outcome), "moderate" (for four outcomes), and "high" (for two outcomes). CONCLUSIONS:Targeting fathers in promotion of BF has provided favorable results for all seven outcomes with satisfactory quality of evidence. This review was registered in the PROSPERO-registry (ID: 2017-CRD42017076163) prior to its commencement.

Dataset Information

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

Publications

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

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