Abstract P2-01-05: Mammographic microcalcifications and breast cancer tumorigenesis: A radiologic-pathologic analysis

Abstract

Background: Microcalcifications (MCs) are tiny deposits of calcium in breast soft tissue. They serve as key diagnostic radiological features for localization of malignancy. Approximately 30% of early invasive breast cancers have fine, granular MCs detectable on mammography; however, their role in breast cancer tumorigenesis is currently unknown. The purpose of this study was to investigate the relationship between mammographic MCs and breast cancer pathology. Methods: A retrospective chart review was performed for 1015 women treated for breast cancer between 2000-2012 at St. Michael's Hospital. Demographic information (age and menopausal status), tumor pathology (size, histology, grade, nodal status and lymphovascular invasion), hormonal status (ER and PR), HER-2 overexpression and presence of MCs were collected for breast cancer patients. Chi-square tests were performed for categorical variables and t-tests were performed for continuous variables. All tests were two-sided and p-values less than 0.05 were considered statistically significant. Results: A total of 1015 patient charts were included; 78 (7.7%) patients had metastatic carcinoma and were excluded from analysis. About 38.3% (287/1015) of the patients presented with mammographic MCs. Patients were more likely to have MCs if they were HER-2 positive (52.9%) as opposed to being HER-2 negative (33.8%) (p<0.001). There was a significant association between MCs and having heterogeneous breast density (p = 0.031) and having multifocal disease (p = 0.044). Patients with invasive ductal carcinomas (40.9%) were more likely to present with MCs than were patients with other tumor histology (p = 0.001). There was a positive correlation between MCs and tumor grade (p = 0.057), with grade III tumors presenting with the most MCs (41.3%), followed by grade II (39.8%) and grade I (30.7%). There was no significant association between mean age, mean tumor size, ER and PR status with the presence of MCs. Conclusion: This is the largest study analyzing data over a 12 year period, suggesting that the appearance of MCs on mammograms is strongly associated with HER-2 overexpression, invasive ductal carcinoma, heterogeneous breast density and multifocal breast cancers. Since HER-2 is implicated in mediating aggressive tumor growth and metastasis, future studies should investigate the molecular pathways connecting HER-2 overexpression and MC development. This would help better understand the role of MCs in breast cancer tumorigenesis. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-01-05.