Effect of Body Mass Index on Breast Cancer during Premenopausal and Postmenopausal Periods: A Meta-Analysis

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Abstract

Objective

There is no universal consensus on the relationship between body mass index (BMI) and breast cancer. This meta-analysis was conducted to estimate the overall effect of overweight and obesity on breast cancer risk during pre- and post-menopausal period.

Data Sources

All major electronic databases were searched until April 2012 including Web of Knowledge, Medline, Scopus, and ScienceDirect. Furthermore, the reference lists and related scientific conference databases were searched.

Review Methods

All prospective cohort and case-control studies investigating the association between BMI and breast cancer were retrieved irrespective of publication date and language. Women were assessed irrespective of age, race and marital status. The exposure of interest was BMI. The primary outcome of interest was all kinds of breast cancers confirmed pathologically. Study quality was assessed using the checklist of STROBE. Study selection and data extraction were performed by two authors separately. The effect measure of choice was risk ratio (RR _i) and rate ratio (RR _a) for cohort studies and odds ratio (OR) in case-control studies.

Results

Of 9163 retrieved studies, 50 studies were included in meta-analysis including 15 cohort studies involving 2,104,203 subjects and 3,414,806 person-years and 35 case-control studies involving 71,216 subjects. There was an inverse but non-significant correlation between BMI and breast cancer risk during premenopausal period: OR = 0.93 (95% CI 0.86, 1.02); RR _i = 0.97 (95% CI 0.82, 1.16); and RR _a = 0.99 (95% CI 0.94, 1.05), but a direct and significant correlation during postmenopausal period: OR = 1.15 (95% CI 1.07, 1.24); RR _i = 1.16 (95% CI 1.08, 1.25); and RR _a = 0.98 (95% CI 0.88, 1.09).

Conclusion

The results of this meta-analysis showed that body mass index has no significant effect on the incidence of breast cancer during premenopausal period. On the other hand, overweight and obesity may have a minimal effect on breast cancer, although significant, but really small and not clinically so important.

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Most cited references 47

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

Reiko Suzuki, Nicola Orsini, Shigehira Saji … (2009)

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. Copyright (c) 2008 Wiley-Liss, Inc.

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Obesity and outcomes in premenopausal and postmenopausal breast cancer.

Sherene Loi, Roger Milne, Michael L Friedlander … (2005)

Obesity is associated with adverse outcomes in postmenopausal women with breast cancer. In premenopausal women, the association is less clear. A population-based sample of 1,360 Australian women with breast cancer before the age of 60 years, 47% diagnosed before age 40, and 74% premenopausal, was studied prospectively for a median of 5 years (range, 0.2-10.8 years). Obesity was defined as a body mass index of > or =30 kg/m2. The hazard ratio (HR) for adverse clinical outcome associated with obesity was estimated using Cox proportional hazard survival models. Obesity increased with age (P or = 0.6) or with first cycle adjuvant chemotherapy dose reductions (P = 0.1). Adjusting for number of axillary nodes, age at diagnosis, tumor size, grade, and hormone receptor status, obese women of all ages were more likely than nonobese women to have disease recurrence [HR, 1.57; 95% confidence interval (95% CI), 1.11-2.22; P = 0.02] and to die from any cause during follow-up (HR, 1.56; 95% CI, 1.01-2.40; P = 0.05). In premenopausal women, the adjusted HRs were 1.50 (95% CI, 1.00-2.26; P = 0.06) and 1.71 (95% CI, 1.05-2.77; P = 0.04), respectively. Obesity is independently associated with poorer outcomes in premenopausal women, as it is in postmenopausal women, and this is not entirely explained by differences in tumor size or nodal status. Given the high and increasing prevalence of obesity in western countries, more research on improving the treatment of obese breast cancer patients is warranted.

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Dual effects of weight and weight gain on breast cancer risk.

Jonathan W. Willett, Charles Hennekens, B Rosner … (1997)

Breast cancer is a major cause of mortality among women. It is important to identify modifiable risk factors for this disease. To examine body mass index (BMI) at the age of 18 years and at midlife and adult weight change in relation to breast cancer incidence and mortality. Cohort study. A cohort of 95256 US female nurses aged 30 to 55 years who were followed up for 16 years. Incident and fatal breast cancer. During 1203498 person-years, 2517 incident breast cancers (60% postmenopausal) were documented. Higher current BMI was associated with lower breast cancer incidence before menopause and was minimally associated with incidence after menopause. However, a stronger positive relationship was seen among postmenopausal women who never used hormone replacement (relative risk=1.59 for BMI >31 kg/m2 vs < or = 20 kg/m2; 95% confidence interval, 1.09-2.32; P for trend <.001). Higher BMI at the age of 18 years was associated with lower breast cancer incidence both before and after menopause. Weight gain after the age of 18 years was unrelated to breast cancer incidence before menopause, but was positively associated with incidence after menopause. This increased risk with weight gain was limited to women who never used postmenopausal hormones; among these women, the relative risk was 1.99 (95% confidence interval, 1.43-2.76) for weight gain of more than 20 kg vs unchanged weight (P for trend <.001). Current BMI and weight gain were even more strongly associated with fatal postmenopausal breast cancer. In this population, the percentage of postmenopausal breast cancer accounted for by weight gain alone was approximately 16% and by hormone replacement therapy alone was 5%, but when the interaction between these variables was considered, together they accounted for about one third of postmenopausal breast cancers. Avoiding adult weight gain may contribute importantly to the prevention of breast cancer after menopause, particularly among women who do not use postmenopausal hormones.

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Author and article information

Contributors

Raul M. Luque: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS ONE

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection: 2012

Publication date (Electronic): 7 December 2012

Volume: 7

Issue: 12

Electronic Location Identifier: e51446

Affiliations

[1 ]Department of Epidemiology & Biostatistics, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran

[2 ]Research Center for Health Sciences and Department of Epidemiology & Biostatistics, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran

[3 ]Fatemieh Hospital, Hamadan University of Medical Sciences, Hamadan, Iran

[4 ]Department of Community Medicine, School of Medicine, Kurdistan University of Medical Sciences, Kurdistan, Iran

University of Cordoba, Spain

Author notes

* E-mail: poorolajal@ 123456umsha.ac.ir

Competing Interests: The authors have declared that no competing interests exist.

Conceived and designed the experiments: ZC JP ADI. Performed the experiments: ZC JP ADI. Analyzed the data: ZC JP ADI. Contributed reagents/materials/analysis tools: ZC JP ADI. Wrote the paper: ZC JP ADI TH NE.

Article

Publisher ID: PONE-D-12-27584

DOI: 10.1371/journal.pone.0051446

PMC ID: 3517558

PubMed ID: 23236502

SO-VID: b18d822f-d85f-4e71-ab76-f8e3147d2560

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Page count

Pages: 9

Funding

This study was funded by the Vice-Chancellor of Research and Technology of Hamadan University of Medical Sciences. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Effect of Body Mass Index on Breast Cancer during Premenopausal and Postmenopausal Periods: A Meta-Analysis

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Abstract

Objective

Data Sources

Review Methods

Results

Conclusion

Related collections

PLOS Climate

Most cited references 47

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

Obesity and outcomes in premenopausal and postmenopausal breast cancer.

Dual effects of weight and weight gain on breast cancer risk.

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