Visscher, Daniel W.

Abstract Gene expression profiling has identified molecular subtypes that classify invasive breast cancers into distinct categories that vary in their clinical behavior and response to treatment. These subtypes highlight the many possible biologically and clinically distinct types of breast cancer. Immunohistochemical (IHC) staining of tumor sections using antibody panels has been used as a surrogate for the molecular subtypes identified through gene expression profiling, resulting in a set of intrinsic molecular subtypes. Given the heterogeneity within breast cancer, one might expect that different risk factors influence specific subtypes of breast cancer through various etiologic pathways. We evaluated whether percent mammographic density (MD), the proportion of fibroglandular or white tissue on a mammogram and one of the strongest and most consistent risk factors for breast cancer, is associated equally with all intrinsic molecular subtypes. Data were pooled from six cohort or case-control studies including 3389 women with invasive breast cancer and 9860 without, who underwent screening mammography. Percent MD was assessed from digitized film-screen mammograms (for cases, at a median 4 years prior to diagnosis) using a computer-assisted threshold technique, and categorized as 0-10%, 11-25%, 26-50% and 51%+. Receptor status was abstracted from clinical pathology records and supplemented by IHC staining of tumor sections or microarrays. With estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (HER2) information, we classified tumors into the intrinsic molecular subtypes: Luminal A ( ER+ and/or PR+ and HER2- and grade 1 or 2), Luminal B (ER+ and/or PR+ and HER2+ or Luminal A and grade 3), HER2 expressing (HER2+/ER-/PR-) and triple negative (ER-/PR-/HER2-). For cancers found to be triple negative (TN), we also stained for epidermal growth factor receptor (EGFR) and cytokeratins (CK) 5/6 to differentiate basal-like tumors (positive for EGFR and/or CK 5/6) from the unclassifieds (negative on both EGFR and CK 5/6). We used polytomous logistic regression to calculate the odds (OR) of each of the intrinsic subtypes of breast cancer by categories of percent MD, adjusting for age, BMI and study. Contrasts were constructed and tested within the polytomous model framework to investigate differences in the strength of association of percent MD across subtypes. On average, cases were slightly older (56.4 years [SD=11.3]) than controls (55.8 [10.9]). Of the 3389 invasive breast cancer cases, 2146 (63%) were classified as Luminal A, 709 (21%) as Luminal B, 169 (5%) as HER-2 expressing, and 365(11%) as triple negative (TN). Of the TN tumors, 203 had tumor tissue available and were evaluated for CK 5/6 and EGFR, with 167 (82%) classified as basal-like and 36 (18%) as unclassified. Percent (%) MD was associated with breast cancer risk across all intrinsic subtypes. For Luminal A, compared to women with 11-25% MD (reference), women with 0-10% MD had a reduced risk of breast cancer (OR=0.64 [95% confidence interval (CI): 0.55, 0.74]) while women with 26-50% MD had an OR=1.5 (1.3,1.7) and women with 51%+ MD had the highest risk, OR=2.4 (2.0, 2.8). Similar associations were seen for Luminal B, HER2 expressing, and TN across percent MD categories. The small differences among the percent MD-breast cancer associations observed for the different subtypes were not statistically significant, either when comparing the four (Luminal A, Luminal B, HER-2 expressing and TN; p=0.61) or five categories of subtypes (Luminal A, Luminal B, HER-2 expressing, basal-like, unclassified; p=0.66). Our results suggest percent MD is a risk factor for all intrinsic molecular subtypes. Additional study is needed to examine whether these results hold for younger and older aged women. Understanding the importance of mammographic density measures for subtypes of breast cancer has significance for development of subtype-specific risk models. Citation Format: Celine Vachon, Rulla Tamimi, Yunn-Yi Chen, Christopher Scott, Kimberly Bertrand, Matthew Jensen, Daniel Visscher, Aaron Norman, Fergus Couch, John Shepherd, Bo Fan, Fang-Fang Wu, Lin Ma, Andrew Beck, Steve Cummings, V. Shane Pankratz, Karla Kerlikowske. Mammographic density: A risk factor for all breast cancers or only specific subtypes? [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr IA22.

BACKGROUNDWomen with benign breast disease (BBD) have an increased risk of developing breast cancer (BC). Nearly 30% of all BCs develop in women with prior BBD. Information regarding features of the expected number of BCs after BBD would enhance individualized surveillance and prevention strategies for these women. In the current study, the authors sought to characterize BCs developing in a large cohort of women with BBD.METHODSThe current study cohort included 13,485 women who underwent breast biopsy for mammographic or palpable concerns between 1967 and 2001. Biopsy slides were reviewed and classified as nonproliferative disease, proliferative disease without atypia, or atypical hyperplasia. BCs were identified by follow‐up questionnaires, medical records, and Tumor Registry data. BC tissues were obtained and reviewed.RESULTSWith median follow‐up of 15.8 years, 1273 women developed BC. The majority of BCs were invasive (81%), of which 61% were ductal, 13% were mixed ductal/lobular, and 14% were lobular. Approximately two‐thirds of the BC cases were intermediate or high grade, and 29% were lymph node positive. Cancer characteristics were similar across the 3 histologic categories of BBD, with a similar frequency of ductal carcinoma in situ, invasive disease, tumor size, time to invasive BC, histologic type of BC, lymph node positivity, and human epidermal growth factor receptor 2 positivity. Women with atypical hyperplasia were found to have a higher frequency of estrogen receptor‐positive BC (91%) compared with women with proliferative disease without atypia (80%) or nonproliferative disease (85%) (P = .02).CONCLUSIONSA substantial percentage of all BCs develop in women with prior BBD. The majority of BCs after BBD are invasive tumors of ductal type, with a substantial number demonstrating lymph node positivity. Of all the BCs in the current study, 84% were estrogen receptor positive. Prevention therapy should be strongly encouraged in higher‐risk women with BBD. Cancer 2016;122:378–385. © 2015 American Cancer Society.

Abstract Introduction: CD56+ lymphocytes (a defining marker of natural killer cells) have a predominantly cytotoxic phenotype and a hypothetical role in breast tumor immunosurveillance. Here we investigate whether CD56+ staining density varies in nonmalignant breast lobules according to confirmed breast cancer risk factors- age, and histologic features of fibrocystic change and lobular involution. Methods: Archived breast tissue samples were obtained from 94 women with benign breast disease (BBD). The sample set was selected as a nested case-control study (47 cases, 47 controls) from within a large BBD cohort; cases were those who developed breast cancer subsequent to their benign breast biopsy; controls were matched to cases on age at biopsy, year of biopsy, and length of breast cancer free follow-up at least as long as the time-to-cancer in the matched case. Up to 10 representative lobules in each sample were characterized by H&E for fibrocystic changes and the degree of epithelial proliferation (normal, nonproliferative, proliferative, atypia) and for degree of lobular involution (none, partial, complete). Consecutive sections were immunostained for CD56 and hematoxylin. Using digital image analysis, CD56 staining was quantified on a per lobule basis by pixel ratio (PR) (positive stain:total lobule). Statistical analysis was performed using linear mixed effects regression on the rank transformed density to account for correlations among multiple lobules from the same patient in assessing the association of density with lobule characteristics and using conditional logistic regression for association with case-control status. Results: Among 94 women (median age 52, range 35-73), 876 lobules were evaluated: 431 in BBD cases and 445 in BBD controls. Overall, 391 lobules (45%) were normal and the remaining 485 (55%) demonstrated fibrocystic changes. Among fibrocystic lobules, 247 (51%) had nonproliferative changes, 218 (45%) had epithelial proliferation, and 20 (4%) had atypical hyperplasia. Among normal lobules, 61 (16%) had no involution, 139 (36%) had partial involution, and 191 (49%) had complete involution. The vast majority of lobules (861/876, 98%) demonstrated presence of CD56+ cells, while only 15 of 876 lobules in 11 patients had zero CD56+ cells [7 cases (15%) versus 4 controls (8.5%) OR 1.75, p = 0.37]. The median CD56+ PR was 0.55% overall. Fibrocystic lobules as a group showed significantly lower median CD56+ PR compared to normal lobules (0.37% vs 0.85%, p < 0.0001). Among subcategories of fibrocystic lobules, the median CD56+ PR was lower in proliferative lobules (0.29%) compared to non-proliferative (0.42%), but this difference was not statistically significant (p = 0.55). Older women (age > 55) showed the highest CD56+ PR (median of 0.92%), as compared to 0.38% in women 45-55 (p=0.02), and 0.52% in women age <45 (p = 0.26). Among normal lobules, median CD56+ PR was similar between lobules with no involution (0.55%) and partial involution (0.52%) but was considerably higher among lobules with complete involution (1.3%, p = 0.09 and p = 0.05, respectively). In a multivariable model, CD56+ PR differences between fibrocystic and normal lobules remained significant (p = 0.0002) and also remained significant between age groups of > 55 and 45-55 (p = 0.02), while involution was non-significant. Median CD56+ PR was lower in cases (0.43%) compared to controls (0.72%), but this was not statistically significant (p=0.19) in our sample of 47 case-control pairs. Conclusions: Breast lobules with fibrocystic changes show less CD56+ cells, raising a question of possible immune suppression induced by early epithelial abnormalities. These findings encourage further investigation to improve understanding of the immune microenvironment in premalignant breast tissues. Citation Format: Rushin D. Brahmbhatt, Daniel Kerekes, Tanya L. Hoskin, Alvaro Pena, Daniel W. Visscher, Melody L. Stallings-Mann, Derek C. Radisky, Linda M. Murphy, Vernon Shane Pankratz, Keith L. Knutson, Marlene Frost, Amy C. Degnim. CD56+ immune cell infiltration is decreased in benign breast lobules with fibrocystic changes. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B34.

Abstract Introduction: Estrogen receptor beta (ERβ), which is highly expressed in benign breast epithelium, is postulated to function as a tumor suppressor of breast cancer. Atypias of the breast increase the lifetime risk of breast cancer four-fold. However, little is known about ERβ expression in association with atypias or whether ERβ plays a role in mitigating breast cancer risk in high-risk individuals. We therefore undertook this study to examine the relationship of ERβ expression in atypias and adjacent normal lobules with the risk of subsequent breast cancer. Methods: We studied women in a well-characterized benign breast disease cohort with atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia (ALH) diagnosed from 1967 to 1991. Nuclear and cytoplasmic ERβ expression was assessed via immunohistochemistry in both the atypical hyperplasia epithelium (atypia) and background normal lobules for percent (scores 0-4 for <1%, 1-25%, 26-50%, 51-75%, >75%, respectively) and intensity (scores 0-3 for negative, weak, intermediate, strong, respectively) using a highly specific ERβ monoclonal antibody (PPG5/10). For nuclear staining, an ERβ sum score (percent + intensity, range 0-7) was created and grouped as low (0-2), moderate (3-5) or high (6-7). Competing risks regression was used to assess the association of ERβ expression with future breast cancer risk while also accounting for the competing risk of death from other causes. Results: 171 women, median age 56, were studied (79 ADH and 92 ALH). Median follow-up was 15 years overall, and 36 women developed breast cancer at a median of 13 years after their atypia biopsy. ERβ expression was lower in the atypia versus normal lobules whether evaluated by nuclear percent stained, nuclear intensity or cytoplasmic intensity (all p < 0.001). For nuclear staining specifically, ERβ expression in the atypia was low in 44 (26%), moderate in 117 (68%) and high in only 10 (6%) based on the sum score. In contrast, ERβ was higher in the normal lobules with a majority showing high expression (n = 96, 56%), moderate expression in 74 (43%) and low expression in only 1 (0.6%). Lower ERβ nuclear expression in the atypia was associated with increased breast cancer risk, whether evaluated by percent staining, intensity or sum score; the same was true for ERβ nuclear expression in the background normal lobules. Low ERβ expression in the atypia (sum score 0-2) was associated with a 2-fold increased risk of subsequent breast cancer compared to atypia with moderate-high expression (sum score 3-7), HR 2.0, 95% CI: 1.02-3.8, p = 0.04. Lower ERβ expression in the normal lobules was also associated with an increased risk of future breast cancer: HR = 2.5 (95% CI: 1.3-5.1, p = 0.009) for low-moderate versus high expression. Conclusions: Increased ERβ expression in normal and atypical lobules was associated with a significantly decreased risk of breast cancer in our high-risk patient cohort. These data suggest that in women with atypical hyperplasia, ERβ expression is protective against the future development of breast cancer. ERβ may serve as a useful biomarker to further stratify breast cancer risk in women with benign breast disease. Citation Format: Tina J. Hieken, Jodi M. Carter, John R. Hawse, IV, Tanya L. Hoskin, Marlene Frost, Lynn C. Hartmann, Derek C. Radisky, Daniel W. Visscher, Vernon S. Pankratz, Amy C. Degnim. ERβ expression and breast cancer risk prediction for women with atypias. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A03.

Abstract Estrogen receptor (ER) β is highly expressed in normal breast epithelium and a putative tumor suppressor. Atypical hyperplasia substantially increases breast cancer risk, but identification of biomarkers to further improve risk stratification is needed. We evaluated ERβ expression in breast tissues from women with atypical hyperplasia and association with subsequent breast cancer risk. ERβ expression was examined by immunohistochemistry in a well-characterized 171-women cohort with atypical hyperplasia diagnosed 1967–1991. Nuclear ERβ percent and intensity was scored in the atypia and adjacent normal lobules. An ERβ sum score (percent + intensity) was calculated and grouped as low, moderate, or high. Competing risks regression was used to assess associations of ERβ expression with breast cancer risk. After 15-year median follow-up, 36 women developed breast cancer. ERβ expression was lower in atypia lobules in than normal lobules, by percent staining and intensity (both P < 0.001). Higher ERβ expression in the atypia or normal lobules, evaluated by percent staining, intensity or sum score, decreased the risk of subsequent breast cancer by 2-fold (P = 0.04) and 2.5-fold (P = 0.006). High normal lobule ERβ expression conferred the strongest protective effect in premenopausal women: the 20-year cumulative incidence of breast cancer was 0% for women younger than 45 years with high versus 31% for low–moderate ERβ expression (P = 0.0008). High ERβ expression was associated with a significantly decreased risk of breast cancer in women with atypical hyperplasia. These data suggest that ERβ may be a useful biomarker for risk stratification and a novel therapeutic target for breast cancer risk reduction. Cancer Prev Res; 8(11); 1084–92. ©2015 AACR.

Abstract Purpose: Breast biopsies with benign findings (benign breast disease [BBD]) outnumber biopsies revealing in-situ or invasive cancer 4:1, providing an opportunity to identify histopathological features that predict breast cancer risk. Greater degrees of involution of terminal duct lobular units (TDLUs), the structures within the breast that produce milk and the primary source of breast cancer precursors, have been inversely associated with breast cancer risk among women with BBD. We recently developed measures to quantitate levels of TDLU involution, which demonstrate high inter/intra pathologist reproducibility. Here we assessed whether TDLU counts/100mm2 and median TDLU span (microns), two measures inversely related to degree of TDLU involution, are associated with subsequent breast cancer risk among women with BBD. Methods: From the Mayo BBD cohort (n = 9,376), we evaluated benign biopsies from 99 women who later developed breast cancer (cases) and 145 age-matched controls who did not develop breast cancer. Digitized images of biopsy sections were reviewed to enumerate TDLUs/mm2 and measure median TDLU span (microns) for up to ten normal TDLUs. Breast cancer risk factors were available from questionnaires or medical records. To assess associations with breast cancer risk, subjects were categorized into quartile levels of TDLU counts and median TDLU spans, based on data from controls. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using multivariable conditional logistic regression models, adjusted for histologic type of BBD, family history of breast cancer and menopausal hormone use. Results: Compared to controls, women who developed breast cancer had higher median number of TDLU counts/100mm2 (28 vs 20, p = 0.03) and larger TDLU spans (300 vs 267 microns, p = 0.14). In multivariable models higher TDLU counts (quartile4 vs. quartile1, OR = 2.44, 95%CI = 0.96-6.19, ptrend = 0.02) and larger TDLU span measures (quartile4 vs. quartile1, OR = 2.83, 95%CI = 1.13-7.06, ptrend = 0.03) were associated with subsequent diagnosis of breast cancer. Combinatorial metrics of TDLU counts with median TDLU span measures identified women at higher risk; specifically, women above the median for both TDLU span and TDLU counts had an OR = 3.75 (95%CI = 1.40-10.00, ptrend = 0.008), compared with women below the median for TDLU span and TDLU counts. Conclusion: These data show that lack of TDLU involution, as measured by increased persistence of TDLU counts, larger median TDLU spans and cross-classification using these measures was associated with increased breast cancer risk among women with BBD, extending prior work in this cohort based on other TDLU involution metrics. Future studies to identify determinants of TDLU involution, its association with breast cancer risk and its potential as an intermediate endpoint in prevention studies warrant consideration. Citation Format: Jonine D. Figueroa, Ruth Pfeiffer, Maya Palakal, Amy C. Degnim, Derek Radisky, Lynn C. Hartmann, Marlene Frost, Melody L. Stallings Mann, Louise A. Brinton, Daphne Papathomas, Daniel Visscher, Mark E. Sherman. Standardized measures of lobular involution and subsequent breast cancer risk among women with benign breast disease. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4682. doi:10.1158/1538-7445.AM2015-4682

Abstract Introduction: The role of macrophages in the tumor microenvironment is of increasing interest for tumor progression and invasion. Here we investigated the difference in CD68+ cell density in tissue samples from women with Benign Breast Disease (BBD) and women with no clinical breast disease from the Komen Tissue Bank (KTB) at Indiana University. Method: Archived breast tissue samples from women with BBD and no clinical breast disease were obtained for this age-matched case-control study. BBD samples included cases [later got Breast Cancer (BC)] and controls (did not get BC). Samples were characterized via H&E stain for epithelial proliferation [normal (N), fibrocystic non-proliferative (NP), proliferative (P), or atypia (A)]. CD68+ cell density was obtained by digital image quantitation on a per lobule basis (Total CD68+ cells/mm2). Statistical analysis was performed with mixed effects regression. Results: Among 276 women (median age 53, range 35-79) comprising 92 age-matched triplets, 2508 lobules were evaluated [789 KTB, 839 BBD case, 880 BBD control]. 1407 (56%) lobules were normal and 1101 (44%) were fibrocystic {NP [613 (56%)], P [448 (41%)] and A [40 (4%)]}. Out of 2508 lobules analyzed, 2362 (94%) had CD68+ cells, while 146 (6%) showed zero CD68+ cells [19 (2%) BBD cases, 20 (2%) BBD controls, 107 (14%) KTB, p<0.0001]. KTB samples showed significantly lower (p<0.0001) CD68+ density (median 136 cells/mm2) as compared to BBD cases (median 313 cells/mm2) and BBD controls (median 299 cells/mm2). (See Table) For each lobule type, KTB samples had lower CD68+ density compared with the same lobule type in BBD samples (p<0.0001). Conclusion: CD68+ cells are more frequent in breast lobules from women with BBD compared to normal donors. This finding in premalignant breast tissues is consistent with inflammation as a driver of tumorigenesis. BBD case (n = 92 patients)BBD control (n = 92 patients)KTB(n = 92 patients)n lobulesMedian (IQR)n lobulesMedian (IQR)n lobulesMedian (IQR)Overall839313 (165 - 538)880299 (164 - 527)789136 (55 - 272)By Lobule TypeNormal344310 (177 - 557)434331 (177 - 567)629128 (55 - 255)All non-normal/fibrocystic lobules combined495314 (157 - 527)446274 (152 - 478)160159 (58 - 393)Fibrocystic non-proliferative231319 (153 - 543)263274 (140 - 496)119163 (71 - 359)Fibrocystic proliferative246295 (153 - 496)169277 (153 - 478)33128 (30 - 385)Atypia18484 (313 - 739)14260 (223 - 375)8216 (0 - 493)IQR - Interquartile range (25th percentile - 75th percentile) Citation Format: Muhammad A. Arshad, Daniel W. Visscher, Tanya L. Hoskin, Rushin D. Brahmbhatt, Alvaro Pena Jimenez, Melody L. Stallings Mann, Erin E. Miller, Linda M. Murphy, Jodi M. Carter, Stacey J. Winham, Keith L. Knutson, Derek C. Radisky, Amy C. Degnim. CD68+ immune cells show different infiltration patterns in tissue samples from women with no clinical breast disease and those who have benign breast disease. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2364. doi:10.1158/1538-7445.AM2015-2364

Abstract Introduction: Increased levels of circulating estrogens are associated with elevated risks of postmenopausal breast cancer. Previously, we showed that levels of sex steroid hormones in breast adipose tissue are positively correlated with circulating hormones. Further evaluation of hormone levels in breast tissues may help to explain the relationship between estrogens and breast cancer risk. Specifically, data suggest that focal breast lesions consisting of macrophages encircling dying adipocytes, referred to as “crown-like structures (CLS)”, are associated with increased aromatase activity, which could increase conversion of androgens to estrogens locally in the breast. Therefore, we assessed whether the presence of CLS affects the correlations between blood and breast adipose tissue hormone levels. Methods: Participants included 84 postmenopausal women with invasive breast cancer in the Polish Breast Cancer Study, a population based case-control study conducted from 2000 to 2003. We previously reported sex steroid hormone levels in cancer-free breast adipose tissue removed as part of breast excisions performed for cancer. Here, using immunohistochemical stains, we evaluated the number of CD68 positive macrophages and the presence of full CLS (i.e., complete adipocyte encirclement) in benign breast tissue sections prepared from surgical pathology specimens containing breast cancer. The relationship between the number of CD68 positive macrophages per unit area of fat and hormone levels was examined using Spearman rank correlations (rs). We assessed potential effect modification of the association between blood and tissue hormone levels by presence or absence of CLS by including an interaction term in linear regression models. Results: The number of CD68 positive macrophages per unit area of fat was not significantly correlated with levels of estrone, estradiol, androstenedione or testosterone measured in blood (rs = 0.001, -0.04, -0.07, and -0.09, respectively; p>0.05) or breast adipose tissue (rs = -0.15, 0.06, -0.06, and -0.08, respectively; p>0.05). Correlations between serum and adipose tissue hormones did not statistically significantly differ between women with CLS (n = 30) compared to those without CLS (n = 54). CLS were found more frequently in breast adipose tissue from overweight (i.e., women with a body mass index (BMI) between 25 and 29.9) (43%) and obese women (BMI >30) (30%) versus normal weight women, with (BMI between 18.5 and 24.9), (27%); (p = 0.04, χ2 test). The number of CD68 positive macrophages per unit area of fat was not significantly related to BMI (p = 0.31). Conclusion: Among postmenopausal women with invasive breast cancer, the presence of CLS was more common among overweight and obese women, but CLS did not influence the correlation between circulating and breast adipose tissue sex steroid hormone levels. Citation Format: Maeve Mullooly, Hannah P. Yang, Roni T. Falk, Sarah Nyante, Renata Cora, Ruth M. Pfeiffer, Derek C. Radisky, Daniel W. Visscher, Lynn C. Hartmann, Amy C. Degnim, Frank Z. Stanczyk, Jonine F. Figueroa, Montserrat Garcia-Closas, Jolanta Lissowska, Melissa T. Troester, Louise A. Brinton, Mark E. Sherman, Gretchen L. Gierach. Investigation of the relationship between crown-like structures and adipose tissue hormone levels among postmenopausal women with breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2767. doi:10.1158/1538-7445.AM2015-2767