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Héctor A Velásquez García,1,2 Carolyn C Gotay,1 Christine M Wilson,3 Caroline A Lohrisch,4 Agnes S Lai,2 Kristan J Aronson,5 John J Spinelli1,21School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada; 2Population Oncology, BC Cancer, Vancouver, BC, Canada; 3Screening Mammography Program, BC Cancer, Vancouver, BC, Canada; 4Department of Medical Oncology, BC Cancer, Vancouver, BC, Canada; 5Department of Public Health Sciences and Division of Cancer Care and Epidemiology, Cancer Research Institute, Queen’s University, Kingston, ON, CanadaCorrespondence: Héctor A Velásquez GarcíaPopulation Oncology, BC Cancer, 8 th floor, 686 West Broadway, Vancouver, BC V5Z 1G1, CanadaTel +1604 877 6068Fax +1 604 877 6212Email hector.velasquezgarcia@alumni.ubc.caPurpose: Mammographic density is an important breast cancer risk factor, although it is not clear whether the association differs across breast cancer tumor subtypes. We examined the association between indicators of mammographic density and breast cancer risk by tumor subtype among postmenopausal women by investigating heterogeneity across tumor characteristics.Methods: Mammographic density measures were determined for 477 breast cancer cases and 588 controls, all postmenopausal, in Vancouver, British Columbia, using digitized screening mammograms and Cumulus software. Mammographic dense (DA), non-dense (NDA), and percent dense (PDA) areas were treated as continuous covariates and categorized into quartiles according to the distribution in controls. For cases only, tests for heterogeneity between tumor subtypes were assessed by multinomial logistic regression. Associations between mammographic density and breast cancer risk were modeled for each subtype separately through unconditional logistic regression.Results: Heterogeneity was apparent for the association of PDA with tumor size (p-heterogeneity=0.04). Risk did not differ across the other assessed tumor characteristics (p-heterogeneity values >0.05).Conclusion: These findings do not provide strong evidence that mammographic density parameters differentially affect specific breast cancer tumor characteristics.Keywords: mammographic density, breast cancer, tumor characteristics, heterogeneity, multinomial logistic regression |
