Reproductive factors and mammographic density within the International Consortium of Mammographic Density: A cross-sectional study

Jessica O'Driscoll, School of Population Health, RCSI University of Medicine and Health Sciences, Beaux Lane House, Mercer Street Lower, Dublin 2, Ireland. jessicaodriscol20@rcsi.com.
Anya Burton, Bristol Medical School, Translational Health Sciences, University of Bristol, Learning and Research Building, Level 2, Southmead Hospital, Bristol, UK.
Gertraud Maskarinec, University of Hawaii Cancer Center, Honolulu, HI, USA.
Beatriz Perez-Gomez, Instituto de Salud Carlos III, Madrid, Spain.
Celine Vachon, Department of Quantitative Health Sciences, Division of Epidemiology, Mayo Clinic, Rochester, MN, USA.
Hui Miao, Saw Swee Hock School of Public Health, National University of Singapore, Singapore City, Singapore.
Martín Lajous, Instituto Nacional de Salud Pública, Cuernavaca, Mexico.
Ruy López-Ridaura, Instituto Nacional de Salud Pública, Cuernavaca, Mexico.
A Heather Eliassen, Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
Ana Pereira, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.
Maria Luisa Garmendia, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.
Rulla M. Tamimi, Population Health Sciences, Weill Cornell Medicine, New York, NY, USA.
Kimberly Bertrand, Slone Epidemiology Center, Boston University, Boston, MA, USA.
Ava Kwong, Division of Breast Surgery, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China.
Giske Ursin, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway.
Eunjung Lee, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, Los Angeles, USA.
Samera A. Qureshi, Unit for Migration & Health, Norwegian Institute of Public Health, Oslo, Norway.
Huiyan Ma, Department of Computational and Quantitative Medicine, City of Hope National Medical Center, Duarte, CA, USA.
Sarah Vinnicombe, Division of Cancer Research, Ninewells Hospital and Medical School, Dundee, UK.
Sue Moss, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK.
Steve Allen, Department of Diagnostic Radiology, Royal Marsden NHS Foundation Trust, London, UK.
Rose Ndumia, Aga Khan University Hospital, Nairobi, Kenya.
Sudhir Vinayak, Aga Khan University Hospital, Nairobi, Kenya.
Soo-Hwang Teo, Breast Cancer Research Group, University of Malaya Medical Centre, University of Malaya, Kuala Lumpur, Malaysia.
Shivaani Mariapun, Cancer Research Malaysia, Subang Jaya, Malaysia.
Farhana Fadzli, Breast Cancer Research Unit, Faculty of Medicine, University of Malaya Cancer Research Institute, University of Malaya, Kuala Lumpur, Malaysia.
Beata Peplonska, Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine, Łódź, Poland.
Chisato Nagata, Department of Epidemiology & Preventive Medicine, Graduate School of Medicine, Gifu University, Gifu, Japan.
Jennifer Stone, Genetic Epidemiology Group, School of Population and Global Health, University of Western Australia, Perth, WA, Australia.
John L. Hopper, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia.
Graham Giles, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia.
Vahit Ozmen, Faculty of Medicine, Istanbul University, Istanbul, Turkey.

Document Type

Journal Article

Publication Date

9-30-2024

Journal

Breast cancer research : BCR

Volume

26

Issue

1

DOI

10.1186/s13058-024-01890-x

Keywords

Age at first birth; Breastfeeding; Mammographic density; Parity; Reproductive factors

Abstract

BACKGROUND: Elevated mammographic density (MD) for a woman's age and body mass index (BMI) is an established breast cancer risk factor. The relationship of parity, age at first birth, and breastfeeding with MD is less clear. We examined the associations of these factors with MD within the International Consortium of Mammographic Density (ICMD). METHODS: ICMD is a consortium of 27 studies with pooled individual-level epidemiological and MD data from 11,755 women without breast cancer aged 35-85 years from 22 countries, capturing 40 country-& ethnicity-specific population groups. MD was measured using the area-based tool Cumulus. Meta-analyses across population groups and pooled analyses were used to examine linear regression associations of square-root (√) transformed MD measures (percent MD (PMD), dense area (DA), and non-dense area (NDA)) with parity, age at first birth, ever/never breastfed and lifetime breastfeeding duration. Models were adjusted for age at mammogram, age at menarche, BMI, menopausal status, use of hormone replacement therapy, calibration method, mammogram view and reader, and parity and age at first birth when not the association of interest. RESULTS: Among 10,988 women included in these analyses, 90.1% (n = 9,895) were parous, of whom 13% (n = 1,286) had ≥ five births. The mean age at first birth was 24.3 years (Standard deviation = 5.1). Increasing parity (per birth) was inversely associated with √PMD (β: - 0.05, 95% confidence interval (CI): - 0.07, - 0.03) and √DA (β: - 0.08, 95% CI: - 0.12, - 0.05) with this trend evident until at least nine births. Women who were older at first birth (per five-year increase) had higher √PMD (β:0.06, 95% CI:0.03, 0.10) and √DA (β:0.06, 95% CI:0.02, 0.10), and lower √NDA (β: - 0.06, 95% CI: - 0.11, - 0.01). In stratified analyses, this association was only evident in women who were post-menopausal at MD assessment. Among parous women, no associations were found between ever/never breastfed or lifetime breastfeeding duration (per six-month increase) and √MD. CONCLUSIONS: Associations with higher parity and older age at first birth with √MD were consistent with the direction of their respective associations with breast cancer risk. Further research is needed to understand reproductive factor-related differences in the composition of breast tissue and their associations with breast cancer risk.

Department

School of Medicine and Health Sciences Resident Works

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