Mammographic density (MD) is a quantitative trait, measurable in all women, and is among the strongest markers of breast cancer risk. The population-based epidemiology of MD has revealed genetic, lifestyle and societal/environmental determinants, but studies have largely been conducted in women with similar westernized lifestyles living in countries with high breast cancer incidence rates. To benefit from the heterogeneity in risk factors and their combinations worldwide, we created an International Consortium on Mammographic Density (ICMD) to pool individual-level epidemiological and MD data from general population studies worldwide. ICMD aims to characterize determinants of MD more precisely, and to evaluate whether they are consistent across populations worldwide. We included 11755 women, from 27 studies in 22 countries, on whom individual-level risk factor data were pooled and original mammographic images were re-read for ICMD to obtain standardized comparable MD data. In the present article, we present (i) the rationale for this consortium; (ii) characteristics of the studies and women included; and (iii) study methodology to obtain comparable MD data from original re-read films. We also highlight the risk factor heterogeneity captured by such an effort and, thus, the unique insight the pooled study promises to offer through wider exposure ranges, different confounding structures and enhanced power for sub-group analyses.
Bibliographical noteFunding Information:
M. Lajous has received a non-restricted investigator-initiated grant from Astra Zeneca and minor support from Swiss Re. All other coauthors: none.
This work was supported by the US National Cancer Institute at the National Institutes of Health (R03CA167771). The authors would like to thank the IARC Information Technology Services for their immense help with image transfer solutions. Previous studies were supported by: Australia–Australian National Breast Cancer Foundation (to JS), MCCS by VicHealth, Cancer Council Victoria and Australian NHMRC grants 209057, 251553 and 504711; Canada – the National Cancer Institute of Canada (to NFB); Chile-Fondecyt 11100238, 1120326, 1130277, 3130532, World Cancer Research Fund 2010/245, Ellison Medical Foundation Grant (to AP); Iran – Isfahan University of Medical Sciences, and assistance from Dr. Vida Razavi and Dr. Shamila Razavi; Israel-The Israel Cancer Association; Rep. of Korea – Asan Medical Center, Seoul, Grant No. 2010-0811; Malaysia – Sime Darby LPGA Tournament and the Ministry of Education University Malaya High Impact Research Grant UM.C/HIR/MOHE/06; Mexico – Ministry of Education of Mexico and ISSSTE’s Medical Directorate staff and regional office in Jalisco for technical and administrative support, National Council of Science and Technology (Mexico) and the American Institute for Cancer Research (10A035); Netherlands EPIC-NL-Europe against Cancer Programme of the European Commission (SANCO), Dutch Ministry of Health, Dutch Cancer Society, ZonMW the Netherlands Organisation for Health Research and Development, and the World Cancer Research Fund (WCRF); Poland – Polish-Norwegian Research Programme (PNRF-243-AI-1/07); Singapore – Clinician Scientist Award from National Medical Research Council and National University Cancer Institute Singapore (NCIS) Centre grant programme from National Medical Research Council; South Africa – Pink Drive; Spain – Spain’s Health Research Fund (Fondo de Investigacion Santiaria) PI060386 and PI09/0790, and Spanish Federation of Breast Cancer Patients (FECMA) EPY1169-10; Turkey – Roche Mustahzarlari San. A.S., Istanbul, Turkey; UK: EPSRC and EP/K020439/1 (to JHH), Breast Cancer Campaign (2007MayPR23), Cancer Research UK (G186/11), Da Costa Foundation; US – National Cancer Institute R01CA85265, R37CA54281, R01CA97396, P50CA116201, R01CA177150, R01CA140286, Cancer Center Support Grant CA15083; CA131332, CA124865, UM1CA186107, UM1CA176726 and the Susan G. Komen Foundation.
© 2015 Elsevier Ltd.
- Breast cancer
- International Consortium
- Mammographic density