Benign Breast Disease Cohort Research Articles

Breast Cancer Risk and Progressive Histology in Serial Benign Biopsies.

Background: More than 1 million women per year in the United States with benign breast biopsies are known to be at elevated risk for breast cancer (BC), with risk stratified on histologic categories of epithelial proliferation. Here we assessed women who had serial benign biopsies over time and how changes in the histologic classification affected BC risk.Methods: In the Mayo Clinic Benign Breast Disease Cohort of 13 466 women, 1414 women had multiple metachronous benign biopsies (10.5%). Both initial and subsequent biopsies were assessed histologically. BC risk for clinical and prognostic factors was assessed using subdistribution models to account for competing risks, and logistic regression/Wilcoxon/chi-square tests to assess covariates. All statistical tests were two-sided.Results: Breast cancer risk for women with serial biopsies, stratified by histologic category in the later biopsies, was similar to women with a single biopsy. We found that changes in histological category between initial and subsequent biopsy statistically significantly impacted BC risk. Women with nonproliferative initial findings and subsequent proliferative findings had an increased risk (hazard ratio [HR] = 1.77, 95% confidence interval [CI] = 1.06 to 2.94, P = .03) compared with no change. Among women with proliferative disease without atypia at initial biopsy, risk decreased if later biopsy regressed to nonproliferative (HR = 0.49, 95% CI = 0.25 to 0.98) and increased if later biopsy showed progression to atypical hyperplasia (HR = 1.49, 95% CI = 0.73 to 3.05) compared with no change (P = .04).Conclusions: We found that breast cancer risk increases in women with progressive epithelial proliferation over time and decreases in women whose biopsies show less proliferation. This finding has important implications for effective clinical management of the 100 000 women per year who have multiple benign breast biopsies.

Mammographic breast density and risk of breast cancer in women with atypical hyperplasia: an observational cohort study from the Mayo Clinic Benign Breast Disease (BBD) cohort

BackgroundAtypical hyperplasia (AH) and mammographic breast density (MBD) are established risk factors for breast cancer (BC), but their joint contributions are not well understood. We examine associations of MBD and BC by histologic impression, including AH, in a subcohort of women from the Mayo Clinic Benign Breast Disease Cohort.MethodsWomen with a diagnosis of BBD and mammogram between 1985 and 2001 were eligible. Histologic impression was assessed via pathology review and coded as non-proliferative disease (NP), proliferative disease without atypia (PDWA) and AH. MBD was assessed clinically using parenchymal pattern (PP) or BI-RADS criteria and categorized as low, moderate or high. Percent density (PD) was also available for a subset of women. BC and clinical information were obtained by questionnaires, medical records and the Mayo Clinic Tumor Registry. Women were followed from date of benign biopsy to BC, death or last contact. Standardized incidence ratios (SIRs) compared the observed number of BCs to expected counts. Cox regression estimated multivariate-adjusted MBD hazard ratios.ResultsOf the 6271 women included in the study, 1132 (18.0%) had low MBD, 2921 (46.6%) had moderate MBD, and 2218 (35.4%) had high MBD. A total of 3532 women (56.3%) had NP, 2269 (36.2%) had PDWA and 470 (7.5%) had AH. Over a median follow-up of 14.3 years, 528 BCs were observed. The association of MBD and BC risk differed by histologic impression (p-interaction = 0.03), such that there was a strong MBD and BC association among NP (p < 0.001) but non-significant associations for PDWA (p = 0.27) and AH (p = 0.96). MBD and BC associations for AH women were not significant within subsets defined by type of MBD measure (PP vs. BI-RADS), age at biopsy, number of foci of AH, type of AH (lobular vs. ductal) and body mass index, and after adjustment for potential confounding variables. Women with atypia who also had high PD (>50%) demonstrated marginal evidence of increased BC risk (SIR 4.98), but results were not statistically significant.ConclusionWe found no evidence of an association between MBD and subsequent BC risk in women with AH.

Standardized measures of lobular involution and subsequent breast cancer risk among women with benign breast disease: a nested case-control study.

Lesser degrees of terminal duct-lobular unit (TDLU) involution predict higher breast cancer risk; however, standardized measures to quantitate levels of TDLU involution have only recently been developed. We assessed whether three standardized measures of TDLU involution, with high intra/inter pathologist reproducibility in normal breast tissue, predict subsequent breast cancer risk among women in the Mayo benign breast disease (BBD) cohort. We performed a masked evaluation of biopsies from 99 women with BBD who subsequently developed breast cancer (cases) after a median of 16.9years and 145 age-matched controls. We assessed three metrics inversely related to TDLU involution: TDLU count/mm(2), median TDLU span (microns, which approximates acini content), and median category of acini counts/TDLU (0-10; 11-20; 21-30; 31-50; >50). Associations with subsequent breast cancer risk for quartiles (or categories of acini counts) of each of these measures were assessed with multivariable conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CI). In multivariable models, women in the highest quartile compared to the lowest quartiles of TDLU counts and TDLU span measures were significantly associated with subsequent breast cancer diagnoses; TDLU counts quartile4 versus quartile1, OR=2.44, 95%CI 0.96-6.19, p-trend=0.02; and TDLU spans, quartile4 versus quartile1, OR=2.83, 95%CI=1.13-7.06, p-trend=0.03. Significant associations with categorical measures of acini counts/TDLU were also observed: compared to women with median category of <10 acini/TDLU, women with >25 acini counts/TDLU were at significantly higher risk, OR=3.40, 95%CI 1.03-11.17, p-trend=0.032. Women with TDLU spans and TDLU count measures above the median were at further increased risk, OR=3.75 (95%CI 1.40-10.00, p-trend=0.008), compared with women below the median for both of these metrics. Similar results were observed for combinatorial metrics of TDLU acini counts/TDLU, and TDLU count. Standardized quantitative measures of TDLU counts and acini counts approximated by TDLU span measures or visually assessed in categories are independently associated with breast cancer risk. Visual assessment of TDLU numbers and acini content, which are highly reproducible between pathologists, could help identify women at high risk for subsequent breast cancer among the million women diagnosed annually with BBD in the US.

Abstract LB-364: Natural history of age-related lobular involution and impact on breast cancer risk

Abstract Background: Age-related lobular involution (LI) is a physiological process in which the terminal duct lobular units of the breast regress as a woman ages. Analyses of breast biopsies from women with benign breast disease (BBD) have found that extent of LI is negatively associated with subsequent breast cancer development. Here we assess the natural course of LI within individual women, and the impact of progressive LI on breast cancer risk. Methods: The Mayo Clinic BBD cohort consists of 13,455 women with BBD from 1967-2001. The BBD cohort includes 1115 women who had multiple benign biopsies, 106 of whom had developed breast cancer. Within this multiple biopsy cohort, the progression of the LI process was examined by age at initial biopsy and time between biopsies. The relationship between LI progression and breast cancer risk was assessed using standardized incidence ratios (SIRs) and by Cox proportional hazards analysis. Results: Women who had multiple biopsies were younger age and had a slightly higher family history of breast cancer as compared with the overall BBD cohort. Extent of LI at subsequent biopsy was greater with increasing time between biopsies and for women age 55+ at initial biopsy. Among women with multiple biopsies, there was a significant association of higher breast cancer risk among those with involution stasis (lack of progression, HR 1.63) as compared with those with involution progression, p = 0.036. Conclusions: The multiple biopsy BBD cohort allows for a longitudinal study of the natural progression of LI. The majority of women in the multiple biopsy cohort showed progression of LI status between benign biopsies, and extent of progression was highest for women who were in the perimenopausal age range at initial biopsy. Progression of LI status between initial and subsequent biopsy was associated with decreased breast cancer risk. Citation Format: Derek Radisky, Daniel W. Visscher, Ryan Frank, Robert A. Vierkant, Stacey J. Winham, Melody L. Stallings-Mann, Tanya L. Hoskin, Aziza Nassar, Celine M. Vachon, Lori A. Denison, Lynn C. Hartmann, Marlene H. Frost, Amy C. Degnim. Natural history of age-related lobular involution and impact on breast cancer risk. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-364.

Abstract 1769: Presence of cysts in benign breast tissue and the risk of subsequent breast cancer in African American women

Abstract Introduction: Benign breast disease (BBD) is an established risk factor for developing breast cancer, and certain pathologic features in benign breast tissue are more strongly associated with breast cancer risk. Most of the studies evaluating BBD and breast cancer risk have been done in primarily white populations. Our previous work among African American (AA) women with BBD suggested the presence of cysts was associated with increased breast cancer risk. This finding may be unique to AA women as other studies among white populations have not replicated these findings. We sought to further explore the association between breast cysts and breast cancer risk in our expanded AA BBD cohort. Methods: Biopsies from AA women initially diagnosed with BBD from 1997 to 2009 were examined for 14 pathologic features, including the microscopic presence of cysts, and followed for subsequent breast cancer. The association between cysts and the other pathologic features were compared using chi-square tests, and the risk of developing breast cancer was estimated using logistic regression and summarized with odds ratios (OR) and 95% confidence intervals (95% CI). Results: A total of 3,360 AA women with BBD have been identified and their benign biopsies reviewed. 190 women have developed a subsequent breast cancer with a mean follow-up time of 11.5 years. Cysts were present on 1,366 (38%) of the biopsies, and were significantly associated with nearly all of the other benign features evaluated: apocrine metaplasia, ductal hyperplasia, calcifications, duct ectasia, fibrodenomas, fibrosis, intra-ductal papillomas, sclerosing adenosis, columnar alterations, mucocelle-like lesions, radial scars, and proliferation with and without atypia (all p&amp;lt;0.001). Adjusting for age and year of biopsy, cysts were associated with a 36% increase in breast cancer risk (OR: 1.36, 95% CI 1.01 - 1.82). When further adjusted for hyperplasia with atypia, the benign feature with the most established and strongest association with breast cancer risk, the risk associated with cysts was attenuated (OR: 1.20, 95% CI 0.88 - 1.64). Conclusion: Among AA women, cysts are highly correlated with other BBD features that increase subsequent breast cancer risk, but the risk associated with cysts does not appear to be independent of hyperplasia with atypia. Understanding the etiology of BBD and cyst development may provide insight into breast tumorigenesis, and the interplay between cysts and other BBD features warrant further investigation. Citation Format: Julie J. Ruterbusch, Michele L. Cote, Sudeshna Bandyopadhyay, Baraa Alosh, Eman Abdulfatah, Vishakha Pardeshi, Woodlyne Roquiz, Daniel Visscher, Rouba Ali-Fehmi. Presence of cysts in benign breast tissue and the risk of subsequent breast cancer in African American women. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1769.

Abstract P6-09-05: No evidence of association between mammographic breast density and risk of breast cancer in women with atypical hyperplasia

Abstract Background Women with atypical hyperplasia (AH) are at an approximately four-fold increased risk of subsequent breast cancer (BC). Mammographic breast density (MBD) is a well-established risk factor for BC, but its contribution to BC risk in women with AH remains an open question. We previously reported no association between MBD [measured by Wolfe's parenchymal pattern (PP)] and BC risk in a cohort of 147 women with AH. Here, we present results in an expanded cohort of 459 women diagnosed with AH between 1985 and 2001. Methods The Mayo Clinic Benign Breast Disease Cohort includes 13,485 women who had benign core and/or excisional biopsy 1967-2001. Biopsy tissues were reviewed by our study pathologist to determine presence of AH. MBD was available from clinical records starting in 1985, coded as PP (the standard for 1985-1996) or BI-RADS (1997-2001) density criteria. The original four-level PP (N1-fatty, P1-ductal prominence &amp;lt;25% of breast, P2-ductal prominence &amp;gt;25%, DY-dysplasia) and BI-RADS (fatty, scattered densities, heterogeneously dense, extremely dense) measures were re-categorized as low, moderate or high MBD by combining the middle two categories for each. BC events and clinical information were obtained by questionnaires, medical records and the Mayo Clinic Tumor Registry. Women were followed from benign biopsy to date of BC, death or last contact. Standardized incidence ratios (SIRs) were generated overall and within subgroups defined by density measure (PP vs. BI-RADS), number of atypical foci, and BMI by dividing the observed number of BCs by population-based expected values. Cox regression was used to estimate MBD hazard ratios after adjustment for demographic and clinical variables. Results Of the 551 women diagnosed with AH between 1985 and 2001, 459 (83%) had MBD data within 1 year prior to biopsy. Of these, 68 (15%) had low, 221 (48%) had moderate, and 170 (37%) had high MBD, respectively. Over a median follow-up of 11.7 years, 80 BCs were observed. SIRs for breast cancer did not differ significantly across density categories, overall or within any subgroups examined (see Table). Cox regression adjusting for age, BMI and density measure (PP vs. BI-RADS) also failed to identify an association with MBD (p=0.55). Low MBDModerate MBDHigh MBD N / BCsSIR (95% CI)N / BCsSIR (95% CI)N / BCsSIR (95% CI)P-valueOverall68/123.5 (1.8,6.1)221/393.6 (2.5,4.9)170/293.4 (2.3,4.8)0.97MBD Measure PP59/113.6 (1.8,6.5)85/153.0 (1.7,5.0)130/243.3 (2.2,5.0)0.87BI-RADS9/12.7 (0.1,14.7)136/244.0 (2.6,6.0)40/53.4 (1.1,7.9)0.90No. Atypical Foci 147/62.3 (0.9,5.1)123/182.8 (1.7,4.4)96/163.5 (2.0,5.8)0.63214/47.5 (2.0,19.1)58/134.8 (2.6,8.3)41/62.5 (0.9,5.5)0.213+7/26.7 (0.8,24.0)40/84.4 (1.9,8.6)33/74.0 (1.0,8.2)0.83BMI &amp;lt;2525/21.5 (0.2,5.4)75/184.9 (2.9,7.7)101/173.4 (2.0,5.5)0.1625-2919/54.9 (1.6,11.3)68/92.8 (1.3,5.2)36/42.1 (0.6,5.4)0.4530+23/54.8 (1.6,11.2)76/123.0 (1.6,5.3)32/74.0 (1.6,8.2)0.67SIRs compare observed numer of BCs to expected using Iowa SEER data. Analyses account for the effects of age and calendar period. P-value is test of heterogeneity in SIRs across columns. Conclusions We found no evidence of an association between MBD and subsequent BC in women with AH. Citation Format: Vierkant RA, Degnim AC, Hartmann LC, Frank RD, Radisky DC, Visscher DW, Frost MH, Winham SJ, Ghosh K, Vachon CM. No evidence of association between mammographic breast density and risk of breast cancer in women with atypical hyperplasia. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-09-05.

Natural history of age-related lobular involution and impact on breast cancer risk.

Age-related lobular involution (LI) is a physiological process in which the terminal duct lobular units of the breast regress as a woman ages. Analyses of breast biopsies from women with benign breast disease (BBD) have found that extent of LI is negatively associated with subsequent breast cancer development. Here we assess the natural course of LI within individual women, and the impact of progressive LI on breast cancer risk. The Mayo Clinic BBD cohort consists of 13,455 women with BBD from 1967 to 2001. The BBD cohort includes 1115 women who had multiple benign biopsies, 106 of whom had developed breast cancer. Within this multiple biopsy cohort, the progression of the LI process was examined by age at initial biopsy and time between biopsies. The relationship between LI progression and breast cancer risk was assessed using standardized incidence ratios and by Cox proportional hazards analysis. Women who had multiple biopsies were younger age and had a slightly higher family history of breast cancer as compared with the overall BBD cohort. Extent of LI at subsequent biopsy was greater with increasing time between biopsies and for women age 55 + at initial biopsy. Among women with multiple biopsies, there was a significant association of higher breast cancer risk among those with involution stasis (lack of progression, HR 1.63) as compared with those with involution progression, p = 0.036. The multiple biopsy BBD cohort allows for a longitudinal study of the natural progression of LI. The majority of women in the multiple biopsy cohort showed progression of LI status between benign biopsies, and extent of progression was highest for women who were in the perimenopausal age range at initial biopsy. Progression of LI status between initial and subsequent biopsy was associated with decreased breast cancer risk.Electronic supplementary materialThe online version of this article (doi:10.1007/s10549-016-3691-5) contains supplementary material, which is available to authorized users.

Mucocele-like lesions of the breast: a clinical outcome and histologic analysis of 102 cases

Mucocele-like lesions (MLLs) of the breast are characterized by cystic architecture with stromal mucin and frequent atypia, but it is unknown whether they convey long-term breast cancer risk. We evaluated 102 MLLs that were derived from a single-institution benign breast disease cohort of 13412 women who underwent biopsy from 1967 to 2001. MLLs were histologically characterized by type of lining epithelium, architecture of the lesion, associated atypical hyperplasia (AH), and incidence of breast cancer (14.8-year median follow-up). A relatively large proportion of MLLs (42%) were diagnosed in women older than 55 years. AH was significantly more frequent in MLL patient compared to the cohort overall (27% versus 5%; P < .001). Breast cancer has developed in 13 patients with MLL. This frequency is only slightly higher than population expected rates overall (standardized incidence ratio, 2.28; 95% confidence interval, 1.21-3.91) and not significantly different from women in the cohort with (nonatypical) proliferative breast lesions. Younger women (<45) with MLL had a nonsignificant increase in risk of cancer compared to the general population (standardized incidence ratio, 5.16; 95% confidence interval, 1.41-13.23). We conclude that MLL is an uncommon breast lesion that is often associated with coexisting AH. However, in women older than 45 years, MLLs do not convey additional risk of breast cancer beyond that associated with the presence of proliferative disease.

Abstract A03: ERβ expression and breast cancer risk prediction for women with atypias

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 &amp;lt;1%, 1-25%, 26-50%, 51-75%, &amp;gt;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 &amp;lt; 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 B34: CD56+ immune cell infiltration is decreased in benign breast lobules with fibrocystic changes

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&amp;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 &amp;lt; 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 &amp;gt; 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 &amp;lt;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 &amp;gt; 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.

Complex fibroadenoma and breast cancer risk: a Mayo Clinic Benign Breast Disease Cohort Study.

The purpose of this study is to examine the breast cancer risk overall among women with simple fibroadenoma or complex fibroadenoma and to examine the association of complex fibroadenoma with breast cancer through stratification of other breast cancer risks. The study included women aged 18-85 years from the Mayo Clinic Benign Breast Disease Cohort who underwent excisional breast biopsy from 1967 through 1991. Within this cohort, women who had fibroadenoma were compared to women who did not have fibroadenoma. Breast cancer risk (observed versus expected) across fibroadenoma levels was assessed through standardized incidence ratios (SIRs) by using age- and calendar-stratified incidence rates from the Iowa Surveillance, Epidemiology, and End Results registry. Analyses were performed overall, within subgroups of involution status, with other demographic characteristics (age, year of biopsy, indication for biopsy, and family history), and with histologic characteristics, including overall impression [nonproliferative disease, proliferative disease without atypia (PDWA), or atypical hyperplasia]. Fibroadenoma was identified in 2136 women [noncomplex, 1835 (85.9%); complex, 301 (14.1%)]. SIR for noncomplex fibroadenoma was 1.49 (95% CI 1.26-1.74); for complex fibroadenoma, it was 2.27 (95% CI 1.63-3.10) (test for heterogeneity in SIR, P = .02). However, women with complex fibroadenoma were more likely to have other, concomitant high-risk histologic characteristics (e.g., incomplete involution and PDWA). In analyses stratified by involution status and PDWA, complex fibroadenoma was not an independent risk marker for breast cancer. Complex fibroadenoma does not confer increased breast cancer risk beyond other established histologic characteristics.

Abstract P6-10-06: Histologic features of benign breast biopsy tissue and association with ER positive and ER negative breast cancer in the Mayo BBD cohort study

Abstract Introduction: Current models to predict breast cancer risk do not differentiate risk for estrogen receptor (ER) positive and negative breast cancer (BC), despite growing evidence that these tumors are biologically very different. We hypothesized that women with ER+ BC cancers have different clinical risk factors and histologic findings on prior benign breast biopsies than those with ER- BC. Methods: After IRB approval, we examined associations of age at benign biopsy and histologic features of the benign biopsy with ER status of incident BCs within the Mayo Benign Breast Disease Cohort. Benign biopsy slides were reviewed for extent of lobular involution and degree of epithelial proliferation by a single breast pathologist blinded to BC events. Invasive BCs occurring within 15 years after benign biopsy were classified as ER+ if ER staining was &amp;gt;1%. BC case-only associations with ER status were evaluated using multivariate logistic regression. Full-cohort hazard ratios (HR) and 95% confidence intervals (CI) for risk of ER-specific subtypes were estimated using Cox proportion hazards regression. Results: Among 13,410 women undergoing a benign breast biopsy from 1967-2001, 656 invasive BCs (459 ER+, 106 ER, 106 unknown) occurred within 15 years. Women who developed ER+ and ER- BCs were similar in age at the time of their prior benign breast biopsy (p=0.34). Although benign biopsies in women who later developed ER+ BC were more likely to show complete involution (23% vs 15% for ER- BC), this was not statistically significant (p=0.06). However, the degree of epithelial proliferation was significantly associated with ER status of later BCs (p=0.001), with ER+ BCs more likely than ER- BCs to have had a prior biopsy with atypical hyperplasia (16% vs 8%), and ER+ BCs less likely than ER- BCs to have had a prior biopsy with proliferative disease without atypia (33% vs 52%); this association remained after multivariate adjustment (p=0.003). We further pursued the association of epithelial proliferation with differential risk of ER+ and ER- BC in our overall cohort of 13,410 women (Table 1). Compared to women with non-proliferative disease, women with proliferative disease +/- atypia had ∼2-fold hazard ratios for ER- BC, whereas hazard ratios for ER+ BC were higher in women with atypical hyperplasia (∼4-fold) compared to proliferative disease. Hazard Ratio of ER+ and ER- BC within 15 years of BBD based upon degree of epithelial proliferation at benign biopsyCancer TypeGroupNN EventsHazard Ratio (95% CI)p-valueInvasive ER- ≤15 yearsNP8478421.00 (ref)&amp;lt;0.0001 PD4229542.63 (1.76, 3.93) AH70382.60 (1.22, 5.54) Invasive ER+ ≤15 yearsNP84782321.00 (ref)&amp;lt;0.0001 PD42291511.33 (1.09, 1.64) AH703744.41 (3.39, 5.73) NP=nonproliferative disease, PD=proliferative disease without atypia; AH=atypical hyperplasia Conclusion: ER+ and ER- breast cancers appear to have different features on prior benign breast biopsy, with atypical hyperplasia showing increased risk for both types of breast cancer, but a greater risk for ER+ tumors. Citation Format: Amy C Degnim, Derek C Radisky, Robert A Vierkant, Ryan D Frank, Marlene H Frost, Vernon S Pankratz, Celine M Vachon, Tanya L Hoskin, Julie M Cunningham, Chen Wang, Jean-Pierre Kocher, Teresa M Allers, Joanne L Johnson, Tina J Hieken, Karthik Ghosh, Lynn C Hartmann, Daniel W Visscher. Histologic features of benign breast biopsy tissue and association with ER positive and ER negative breast cancer in the Mayo BBD cohort study [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-10-06.

Abstract P6-10-14: Association between mammographic breast density and histologic features of benign breast disease

Abstract Background: Mammographic breast density (MBD) reflects the proportion of fibroglandular tissue in the breast, and is an established risk factor for breast cancer. Benign breast disease (BBD) is also a known risk factor for breast cancer. We previously showed an association between lobular involution (physiologic atrophy) and MBD in a large cohort study of women with BBD. We performed a comprehensive evaluation of the association of histologic features of BBD with MBD. Methods: The Mayo BBD cohort includes women, 18 to 85 years, who were diagnosed with BBD at Mayo Clinic in Rochester, MN between 01/01/1967 and 12/31/1991. For this study, we included women who had a mammogram within 6 months of BBD diagnosis, and diagnosed with BBD between 1985 and 1991 when parenchymal pattern of breast density was clinically recorded. Risk factor information such as age, and body mass index (BMI) was collected from medical records. Parenchymal pattern, assessed clinically and previously used in multiple studies of MBD and risk, classified breast density based on extent and type of density, into four categories: N1 (non-dense, no ducts visible); P1 (ductal prominence occupying &amp;lt;25% breast); P2 (prominent ductal pattern occupying &amp;gt;25% of the breast; DY (homogenous plaque-like areas of density). All assessments of benign breast tissue were performed by expert breast pathologists blinded to both MBD and BBD reports. Histologic characteristics included overall impression (non-proliferative disease (NPD), proliferative disease without atypia (PDWA), and atypical hyperplasia (AH)), proportion of normal lobules that were involuted (no (0%), partial (1 to 74%), or complete (≥75%)), type of AH (ADH or ALH), ductal and lobular hyperplasia, calcifications, sclerosing adenosis, columnar alteration, cyst, fibroadenoma, marked fibrosis, intra-ductal papilloma, radial scar (number and size), duct ectasia, and mucocele like tumors. Associations of parenchymal pattern with BBD characteristics were examined using multicategorical nominal logistic regression models. We first examined associations after adjustment for age and BMI. All variables statistically significant (p&amp;lt;0.05) in these models were then simultaneously included in a fully-adjusted model. Results: Of 2,257 women in the study, 14% were &amp;lt;40 years old, 52.7% between 40- 59 years, and 32.9% were ≥60 years. In this sample, 55.2% of women had NPD, 36% had PDWA, and AH in 8.8%. MBD was classified as N1 in 21.8%, P1 in 12.6%, P2 in 23.7% and DY in 41.9%. Age- and BMI-adjusted analyses showed that there was an association of parenchymal pattern with overall impression, lobular involution, ductal hyperplasia, sclerosing adenosis, columnar alteration, cyst, duct ectasia and fibrosis. Multivariate analyses found that women of younger age (p&amp;lt;0.001) and with lower BMI (p&amp;lt;0.001), presence of fibrosis (p&amp;lt;0.001) and no involution (p=0.016) were more likely to have P2 or DY parenchymal pattern than women without those characteristics. Conclusion: Among women with benign breast disease, higher MBD is associated with younger age, lower BMI, fibrosis, and lack of lobular involution. These findings, concordant with other studies of MBD, provide insight into underlying mechanisms by which MBD and BBD contribute to breast cancer risk. Citation Format: Karthik Ghosh, Robert A Vierkant, Ryan D Frank, Daniel W Visscher, Vernon S Pankratz, Christopher G Scott, Derek C Radisky, Marlene H Frost, Lynn C Hartmann, Amy C Degnim, Celine M Vachon. Association between mammographic breast density and histologic features of benign breast disease [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-10-14.

Ki-67 expression in sclerosing adenosis and adjacent normal breast terminal ductal lobular units: a nested case–control study from the Mayo Benign Breast Disease Cohort

Sclerosing adenosis (SA) increases risk for invasive breast cancer (BC) 2.1 times relative to that in the general population. Here, we sought to evaluate whether the proliferation marker Ki-67 stratifies risk among women with SA. A nested case-control sample of patients with SA was obtained from the Mayo Clinic Benign Breast Disease Cohort. Ki-67 expression was evaluated in SA lesions and in the adjacent normal terminal duct lobular units (TDLU) in women who did (cases, n=133) or did not (controls, n=239) develop BC. Ki-67 was scored by intensity and number of positively stained cells per one high-power field (magnification, ×40) (40×HPF) for both SA and normal TDLU. Associations of Ki-67 expression with case-control status were assessed using conditional logistic regression. Higher Ki-67 expression was significantly associated with case-control status in both SA (P=0.03) and normal background TDLU (P=0.006). For the SA lesion, >2 average positively stained cells/40×HPF showed an adjusted odds ratio (OR) of 1.9 (95% CI, 1.1-3.4) compared to samples with an average of ≤2 positively stained cells. For background TDLU, lobules with >2 but ≤6 average positively stained cells showed an adjusted OR of 1.3-1.5, whereas those with an average of >6 positively stained cells had an OR of 2.4 (95% CI, 1.1-5.3) compared to those with an average of <2 positively stained cells. Among women with SA, increased Ki-67 expression in either the SA lesion or the normal background TDLU carried an approximately twofold increased odds of subsequent BC as compared to lower Ki-67 expression.

Model for individualized prediction of breast cancer risk after a benign breast biopsy.

Optimal early detection and prevention for breast cancer depend on accurate identification of women at increased risk. We present a risk prediction model that incorporates histologic features of biopsy tissues from women with benign breast disease (BBD) and compare its performance to the Breast Cancer Risk Assessment Tool (BCRAT). We estimated the age-specific incidence of breast cancer and death from the Mayo BBD cohort and then combined these estimates with a relative risk model derived from 377 patient cases with breast cancer and 734 matched controls sampled from the Mayo BBD cohort to develop the BBD-to-breast cancer (BBD-BC) risk assessment tool. We validated the model using an independent set of 378 patient cases with breast cancer and 728 matched controls from the Mayo BBD cohort and compared the risk predictions from our model with those from the BCRAT. The BBD-BC model predicts the probability of breast cancer in women with BBD using tissue-based and other risk factors. The concordance statistic from the BBD-BC model was 0.665 in the model development series and 0.629 in the validation series; these values were higher than those from the BCRAT (0.567 and 0.472, respectively). The BCRAT significantly underpredicted breast cancer risk after benign biopsy (P = .004), whereas the BBD-BC predictions were appropriately calibrated to observed cancers (P = .247). We developed a model using both demographic and histologic features to predict breast cancer risk in women with BBD. Our model more accurately classifies a woman's breast cancer risk after a benign biopsy than the BCRAT.

Flat epithelial atypia and risk of breast cancer: A Mayo cohort study.

Based on its cytologic features, and its co-occurrence with atypical hyperplasia and breast cancer, flat epithelial atypia (FEA) has been proposed as a precursor lesion on the pathway to the development of breast cancer. It is often referred to as an "atypical" or high-risk lesion. However, to the authors' knowledge, the long-term risk of breast cancer in women with FEA is undefined. Specimens with FEA were identified among excisional breast biopsies in the Mayo Clinic Benign Breast Disease Cohort, which includes 11,591 women who had benign biopsy findings at the Mayo Clinic in Rochester, Minnesota between 1967 and 2001. Breast cancer risk among subsets of patients with FEA and nonproliferative, proliferative, and atypical hyperplasia (AH) was assessed using standardized incidence ratios (SIRs) compared with the Iowa Surveillance, Epidemiology, and End Results registry. FEA was identified in 282 women (2.4%); 130 had associated AH (46%) and 152 (54%) were classified as having proliferative disease without atypia (PDWA). With median follow-up of 16.8 years, the SIR for breast cancer in patients with AH plus FEA was 4.74 (95% confidence interval [95% CI], 3.17-6.81) versus 4.23 (95% CI, 3.44-5.13) for those with AH without FEA (P = .59). The SIR for patients with PDWA plus FEA was 2.04 (95% CI, 1.23-3.19) versus 1.90 (95% CI, 1.72-2.09) for patients with PDWA without FEA (P = .76). FEA is an uncommon finding in women with benign breast disease. FEA does not appear to convey an independent risk of breast cancer beyond that of the associated PDWA or AH.

Sclerosing adenosis and risk of breast cancer

Over one million American women have a benign breast biopsy annually. Sclerosing adenosis (SA) is a common, but poorly understood benign breast lesion demonstrating increased numbers of distorted lobules accompanied by stromal fibrosis. Few studies of its association with breast cancer have been conducted, with contradictory results. We studied SA in the Mayo Benign Breast Disease (BBD) Cohort, which includes women who had benign biopsies at Mayo-Rochester 1967–2001. Breast cancer risk in defined subsets was assessed using standardized incidence ratios (SIRs), relative to the Iowa Surveillance, Epidemiology, and End Results registry. This BBD cohort of 13,434 women was followed for a median of 15.7 years. SA was present in 3,733 women (27.8 %) who demonstrated an SIR for breast cancer of 2.10 (95 % CI 1.91–2.30) versus an SIR of 1.52 (95 % CI 1.42–1.63) for the 9,701 women without SA. SA was present in 62.4 % of biopsies with proliferative disease without atypia and 55.1 % of biopsies with atypical hyperplasia. The presence of SA stratified risk in subsets of women defined by age, involution status, and family history. However, SA does not further stratify risk in women diagnosed with other forms of proliferative breast disease, either with or without atypia. SA is a common proliferative lesion of the breast which, as a single feature, conveys an approximate doubling of breast cancer risk. Its role in breast carcinogenesis remains undefined; its presence may aid in risk prediction for women after a breast biopsy.

Understanding the premalignant potential of atypical hyperplasia through its natural history: a longitudinal cohort study.

Atypical hyperplasia is a high-risk premalignant lesion of the breast, but its biology is poorly understood. Many believe that atypical ductal hyperplasia (ADH) is a direct precursor for low-grade ductal breast cancer, whereas atypical lobular hyperplasia (ALH) serves as a risk indicator. These assumptions underlie current clinical recommendations. We tested these assumptions by studying the characteristics of the breast cancers that develop in women with ADH or ALH. Using the Mayo Benign Breast Disease Cohort, we identified all women with ADH or ALH from 1967 to 2001 and followed them for later breast cancers, characterizing side of breast cancer versus side of atypia; time to breast cancer; type, histology, and grade of breast cancer, looking for patterns consistent with precursors versus risk indicators. A total of 698 women with atypical hyperplasia were followed a mean of 12.5 years; 143 developed breast cancer. For both ADH and ALH, there is a 2:1 ratio of ipsilateral to contralateral breast cancer. The ipsilateral predominance is marked in the first 5 years, consistent with a precursor phenotype for both ADH and ALH. For both, there is a predominance of invasive ductal cancers with 69% of moderate or high grade. Twenty-five percent are node positive. Both ADH and ALH portend risk for ductal carcinoma in situ and invasive breast cancers, predominantly ductal, with two thirds moderate or high grade. The ipsilateral breast is at especially high risk for breast cancer in the first 5 years after atypia, with risk remaining elevated in both breasts long term. ADH and ALH behave similarly in terms of later breast cancer endpoints.

Abstract P5-01-08: Complex fibroadenoma is not an independent risk marker for breast cancer

Abstract Background: Fibroadenoma (FA) is a relatively common benign breast tumor that can occur in women of any age, with a peak incidence during the second and third decades. The only previous study of this lesion reported that FAs are associated with a 2.2 times increased risk of developing invasive breast cancer (BC) compared to matched controls [1]. This relative risk may increase to 3.1 among patients with complex FA, and remains elevated for decades after diagnosis. However, this study did not thoroughly account for other forms of concomitant risk factors. Our investigative team sought to examine breast cancer risk among women with non-complex and complex FA, overall and stratified by other BC risk factors. Materials and Methods: The study cohort included women between ages 18 to 85 in the Mayo Benign Breast Disease (BBD) Cohort who underwent excisional breast biopsy between 1967and1991 and were found to have a FA. FA was defined histologically as a combination of epithelial and stromal proliferation. Complex FA was defined as FA associated with any of the following features: sclerosing adenosis, epithelial calcifications, papillary apocrine change, and microcysts greater than 3.0 mm. The primary endpoint was a diagnosis of BC, determined using the Mayo medical record and questionnaire information from study participants. A single breast pathologist, blinded to the initial diagnosis and clinical outcome, performed pathology review. Observed vs. expected BC risk across levels of FA was assessed via standardized incidence ratios (SIRs), using age-stratified incidence rates from the Iowa Surveillance, Epidemiology, and End Results (SEER) registry. Analyses were carried out overall and within subgroups of involution status (none, partial, complete) and overall histology (non-proliferative disease [NP], proliferative disease without atypia [PDWA] or atypical hyperplasia [AH]). Results: Of 9097 women in the Mayo BBD Cohort, FA were identified in 2139- non-complex in 1903 (20.9%) and complex in 236 (2.6%). The greatest proportion of FA occurred in the 40–69 age range. The mean ages for women with non-complex FA and complex FA were 45.7 and 50.2 years respectively. The SIR of breast cancer in the overall BBD cohort was 1.5 (95% CI [1.4–1.6]). The SIR among women with non-complex FA was 1.5 (95% CI [1.3–1.8]), and for complex FA increased to 2.41 (95% CI [1.7–3.4]). However, women with complex FA were more likely to have other concomitant high-risk histologic features such as PDWA and incomplete involution. In stratified analyses accounting for involution status and PDWA, complex FA did not demonstrate an independent increase in BC risk. Conclusion: Complex FA does not confer an increased risk for BC beyond other established histologic features. Therefore, women with complex FA should be managed based upon a risk level consistent with the major histologic category of PDWA and/or AH. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-01-08.

Abstract P4-12-03: Towards a risk prediction model for breast cancer that utilizes breast tissue risk features

Abstract Background: Optimal early detection and prevention strategies for breast cancer are predicated on our ability to accurately identify women at increased risk for disease. Current breast cancer risk prediction models rely on clinical and epidemiologic features. As demonstrated with other cancers, such as those of the cervix and colon, cancer risk assessment is enhanced when the tissue at risk is examined for evidence of premalignant abnormalities. Here, we present a multivariate model for individualized breast cancer risk prediction that incorporates tissue features identified from biopsies from women with benign breast disease (BBD). Methods: We used our cohort of more than 9000 women diagnosed with BBD at the Mayo Clinic from 1967–1991, and identified a nested case:control series of 377 women who developed cancer (cases) matched with 734 women who did not (controls). We identified a set of variables that either alone or in two-way interactions contributed to a multivariable risk prediction model. We combined this relative risk model with the baseline incidence of breast cancer and the baseline hazard of death from our full BBD cohort to develop a risk prediction tool that computes absolute risk estimates for breast cancer. We calculated 5-year risk predictions for these cases and controls using our model and using the Gail model and compared c-statistics from these risk predictions. We validated our model using an independent set of 378 breast cancer cases and 728 matched controls drawn from our BBD cohort. Results: Cases and controls in the model development data set differed significantly on a number of features when examined individually. Those included in a multivariable relative risk model for breast cancer among women with BBD are shown below. After including interactions between lobular involution, and histologic impression, with age at first live birth/number of children, and degree of involution with sclerosing adenosis, we devised a model that predicts the absolute risk of breast cancer. Predicted five-year risks in the model development series, we observed a c-statistic of 0.66, higher than the c-statistic of 0.61 for the Gail model. With risk prediction estimates from our validation series of cases and matched controls, the c-statistic of our model decreased to 0.59 and the c-statistic for the Gail model was 0.55. Conclusion: We have identified an initial risk prediction model for breast cancer in women with BBD. The identified model includes basic demographic information as well as a number of histologic features of the tissue samples. Its initial performance is promising, providing improved discrimination over the Gail model in our replication data set. Further work is needed to identify features which might provide additional predictive information for breast cancer risk. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-12-03.