Yaghjyan, Lusine

Abstract Background: High mammographic breast density is a strong, well-established breast cancer risk factor. A recent study found increased expression of stem cell markers in the areas of high breast density, but, whether stem cells may explain high breast cancer risk due to high breast density is unknown. We investigated the association between breast density and the risk of breast cancer by the status of stem cell markers CD44, CD24, and ALDH1A1 in the tumor. Methods: We included 223 postmenopausal women with primary invasive or in-situ breast cancer and 399 age-matched controls from Mayo Clinic Mammography Study. Percent breast density, absolute dense area and non-dense area were assessed using computer-assisted thresholding technique. Immunohistochemical analysis of the markers was performed on tumor tissue microarrays according to a standard protocol with commercial antibodies. Cases with positive staining (≥1% positively stained cells) on one or more cores were considered marker-positive. We used polychotomous logistic regression to quantify the associations of breast density measures with breast cancer risk by the status of each of the markers. Heterogeneity tests were conducted to compare the differences in associations by marker-defined tumor subtypes. Results: Of the 223 cancers in the study, 182 (82%) were positive for CD44, 83 (37%) for CD24 and 52 (23%) for ALDH1A1. Associations of percent density were not significantly different across any of the marker-defined subtypes (density 51%+ vs. 11-25%: OR=2.83, 95% CI 1.49-5.37 for CD44+ vs. OR=1.87, 95% CI 0.47-7.51 for CD44-, p-heterogeneity=0.66; OR=2.80, 95% CI 1.27-6.18 for CD24+ vs. OR=2.44, 95% CI 1.14-5.22 for CD24-, p-heterogeneity=0.61; OR=3.04, 95% CI 1.14-8.10 for ALDH1A1+ vs. OR=2.57. 95% CI 1.30-5.08 for ALDH1A1-, p-heterogeneity=0.94). Positive associations of absolute dense area and inverse associations of non-dense area with breast cancer risk were similar across marker-defined subtypes. Similar associations of breast density measures with breast cancer were seen when cancer subtypes were defined using combined marker expression status (none, one positive marker, or two and more positive markers). Conclusions: We found no evidence of differential associations of breast density measures with breast cancer risk by the status of stem cell markers. However, our power was limited and further studies in larger study populations are warranted to confirm these associations in a larger sample. Citation Format: Lusine Yaghjyan, Ashwini Esnakula, Christopher Scott, Akemi Wijayabahu, Matthew Jensen, Celine Vachon. Associations of mammographic breast density with breast stem cell marker-defined breast cancer subtypes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 592.

Abstract Purpose: The evidence on associations of mammographic breast density with breast cancer risk by combination of tumor aggressiveness features is limited. We examined associations of breast density phenotypes with risk of aggressive breast tumor features by menopausal status, and current postmenopausal hormone therapy. Methods: This study included 2,635 invasive breast cancer cases and 4,059 controls from participants of four nested case-control studies within four established cohorts: the Mayo Mammography Health Study, the Nurses Health Study, Nurses Health Study II, and San Francisco Mammography Registry. Percent breast density, absolute dense and non-dense areas were assessed from digitized film-screen mammograms using a computer-assisted threshold technique and standardized across studies. We used polytomous logistic regression to quantify the associations of breast density measures with risk of breast tumor aggressiveness (defined as presence of 2 or more of the following tumor characteristics: size ≥2cm, grade 2 or 3, or positive nodes), stratified by menopausal status and current hormone therapy (i.e., premenopausal, postmenopausal/estrogen therapy, postmenopausal/combined therapy, and postmenopausal/no hormones). We also evaluated differences in the strength of associations across categories. In a secondary analysis, we examined these associations while excluding cases with mammogram date within 2 years of diagnosis. Results: Positive associations of percent density and dense area and inverse associations of non-dense area with breast cancer risk were stronger in aggressive vs. non-aggressive tumors (OR=2.62, 95%CI 2.08-3.31 vs. OR=1.94, 95%CI 1.62-2.33 for percent density≥51% vs. 11-25%, p-heterogeneity=0.001; OR=1.89, 95%CI 1.54-2.31 vs. OR=1.65, 95%CI 1.41-1.93 for dense area 4th vs. 2nd quartile, p-heterogeneity=0.015; OR=0.56, 95%CI 0.44-0.72 vs. OR=0.71, 95%CI 0.59-0.86 for non-dense area 4th vs 2nd quartile, p-heterogeneity=0.007, respectively). These patterns were similar across all menopausal and hormone therapy groups (P-interactions=0.62, 0.76, and 0.23, for percent density, dense area and non-dense area, respectively). Excluding cases diagnosed within 2 years of mammography resulted in similar findings. Conclusion: Mammographic density phenotypes were more strongly associated with aggressive cancer (having two or more of the following: size ≥2cm, grade 2 or 3, or positive nodes) vs. non-aggressive types of breast cancer across categories of menopause and hormone therapy types. Citation Format: Lusine Yaghjyan, Rulla Tamimi, Kimberly Bertrand, Christopher G. Scott, Matthew R. Jensen, Shane Pankratz, Kathleen Brandt, Daniel Visscher, Aaron Norman, Fergus Cough, John Shepherd, Bo Fan, Yunn-Yi Chen, Lin Ma, Andrew H. Beck, Steven R. Cummings, Karla Kerlikowske, Celine Vachon. Interaction of mammographic breast density with menopausal status and postmenopausal hormone use in relation to the risk of aggressive breast cancer subtypes. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr B27.

Abstract Background: This analysis aimed to determine if associations of prediagnostic mammographic percent breast density, absolute dense area, and absolute non-dense area and risk of breast cancer vary according to the subsequent breast tumors biomarker status. Methods: We included 1,154 postmenopausal women diagnosed with breast cancer between June 1, 1989, and June 30, 2004, and 2,078 matched controls from the Nurses' Health Study I and II. Percent breast density, absolute dense and non-dense areas were estimated from digitized film mammograms using computer assisted thresholding techniques. Density measures were modeled as quartiles. Information on estrogen receptor (ESR1 [ER]), progesterone receptor (PGR [PR]), and human epidermal growth factor receptor 2 (ERBB2 [HER2]) status was obtained from pathology reports and medical records, and if missing, from immunostains performed on paraffin sections of tumor tissue microarrays (TMAs). Other biomarkers assessed on TMAs were androgen receptor (AR), cytokines 5/6 (KRT5/KRT6 [CK5/6]), epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGFA [VEGF]), and cyclooxygenase 2 (PTGS2 [COX2]). Information on breast cancer risk factors was obtained prospectively from biennial questionnaires before the date of cancer diagnosis for cases and matched controls. Polychotomous logistic regression was used to assess associations of the three breast density measures with tumor subtypes based on the status of selected tissue markers. Results: Breast cancer risk was positively associated with percent density and absolute dense area and inversely associated with absolute non-dense area (p for trend<0.0001 for all). The associations of percent density with breast cancer risk did not statistically significantly differ by the status of any of the markers. However, we found stronger positive associations for absolute dense area and KRT5/KRT6- and EGFR- tumors as compared to respective marker-positive tumors (4th vs. 1st quartile: OR=2.99 for KRT5/KRT6- vs. OR=0.92 for KRT5/KRT6+ tumors, p-heterogeneity <0.001; OR=3.06 for EGFR- vs. OR=1.08 for EGFR+ tumors, p-heterogeneity=0.001). Stronger inverse associations of absolute non-dense area with breast cancer risk were found for ESR1- as compared to ESR1+ tumors, and for AR+, KRT5/KRT6+, and EGFR+ tumors as compared to respective marker-negative tumors (4th vs. 1st quartile: OR=0.21 for ESR1- vs. OR=0.59 for ESR1+ tumors, p-heterogeneity <0.0001; OR=0.22 for AR+ vs. OR=0.42 for AR- tumors, p-heterogeneity=0.04; OR=0.21 for KRT5/KRT6+ vs. OR=1.14 for KRT5/KRT6- tumors, p-heterogeneity<0.01; OR=0.37 for EGFR+ vs. OR=1.11 for EGFR- tumors, p-heterogeneity<0.01). There were no differences in associations of the density measures with breast cancer by status of other markers evaluated. Conclusions: The findings suggest that some mammographic density measures are differentially associated with the risk of subsequent breast tumor subtypes. Citation Format: Lusine Yaghjyan, Andreas Pettersson, Graham Colditz, Laura Collins, Stuart Schnitt, Andrew Beck, Bernard Rosner, Celine Vachon, Rulla Tamimi. Mammographic breast density and subsequent risk of breast cancer in postmenopausal women according to the status of selected tissue markers: A case-control study. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr PR09.