Mammography features for early markers of aggressive breast cancer subtypes and tumor characteristics: A population‐based cohort study

Current breast cancer risk models identify mostly less aggressive tumors, although only women developing fatal breast cancer will greatly benefit from early identification. Here, we evaluated the use of mammography features (microcalcification clusters, computer‐generated Breast Imaging Reporting and Data System [cBIRADS] density and lack of breast density reduction) as early markers of aggressive subtypes and tumor characteristics. Mammograms were retrieved from a population‐based cohort of women that were diagnosed with breast cancer from 2001 to 2008 in Stockholm‐Gotland County, Sweden. Tumor and patient characteristics were obtained from Stockholm Breast Cancer Quality Register and the Swedish Cancer Registry. Multinomial logistic regression was used to individually model each mammographic feature as a function of molecular subtypes, tumor characteristics and detection mode. A total of 4546 women with invasive breast cancer were included in the study. Women with microcalcification clusters in the affected breast were more likely to have human epidermal growth factor receptor 2 subtype (odds ratio [OR] 1.78; 95% confidence interval [CI] 1.24‐2.54) and potentially less likely to have basal subtype (OR 0.54; 0.30‐0.96) compared to Luminal A subtype. High mammographic cBIRADS showed association with larger tumor size and interval vs screen‐detected cancers. Lack of density reduction was associated with interval vs screen‐detected cancers (OR 1.43; 1.11‐1.83) and potentially of Luminal B subtype vs Luminal A subtype (OR 1.76; 1.04‐2.99). In conclusion, microcalcification clusters, cBIRADS density and lack of breast density reduction could serve as early markers of particular subtypes and tumor characteristics of breast cancer. This information has the potential to be integrated into risk models to identify women at risk for developing aggressive breast cancer in need of supplemental screening.