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The association between breast density and HER2‑positive breast cancer: A population‑based case‑control study

Posted by Dr. Abdolell, Iles, Payne on May 20, 2020 in Breast
Differences in breast density
Differences in breast density

Dr. Jennifer Payne, Dr. Sian Iles, and Dr. Mohamed Abdolell published a paper on breast density and rates of cancer. See full publication

Background: Little is known about the association between mammographic breast density and the subtypes of breast cancer including HER2-positive breast cancers (HER2-BrCa). The objective of this study was to assess the strength of association between breast density and HER2-BrCa in a population-based screening program. 

Methods: This is a population-based case-control breast cancer study of women aged 40 to 75 who underwent digital breast screening from 2009 to 2015 in Nova Scotia, Canada. Cases included women diagnosed with HER2-BrCa at screen or before their next screen (interval); controls included women without screen-detected cancer matched to cases by age and year of screen. Measures of mammographic breast density (percent density, BI-RADS-4th and -5th edition) were obtained from automated software (densitasai) and linked with clinical risk factor data (age, parity, total breast volume, post-menopausal status, hormone replacement therapy, family history and history of core biopsy). The association between breast density and cancer risk was assessed by calculating the odds ratios [OR] with 95% confidence intervals using multivariable logistic regression. 

Results: A total of 209 cases (median age, 58.8 years) and 6812 controls (median age, 59.4 years) were included. The risk of HER2-BrCa increased with increasing levels of percent breast density. High breast density according to BIRADS-4th and -5th editions was significantly associated with HER2-BrCa: BIRADS -4th 3/4 vs 1: OR 2.50 (1.68 - 3.68); BIRADS-5th C/D vs A: OR 2.58 (1.71 - 4.01). The association between higher breast density and increased risk of HER2-BrCa remained after adjustment for clinical factors. 

Conclusions: The risk of HER2-BrCa was associated with progressively higher mammographic breast density, although to a lesser extent than breast cancer in general. Accurate risk models including breast density may support the development of more breast-screening protocols that can lead to more strategic use of healthcare resources.


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