Benetti, Lorelle L.

Abstract Background: Women with benign breast disease (BBD) have increased breast cancer risk, and histologic features of the lesion stratify individual risk. We hypothesized that the concentration and type of terminal duct lobular units in BBD tissue is associated with future breast cancer risk. Methods: A nested case-control series of 770 breast cancer cases and 1273 age- and year of biopsy-matched controls was identified within a cohort of 13,647 women with BBD from 1967-2001 (median follow-up 15.3 years). One representative H&E slide from each biopsy was reviewed by a single pathologist, who recorded total # of lobules present, and # of fibrocystic lobules (total and # with epithelial proliferation). Samples were also evaluated for lobular involution and primary BBD histology. Lobule density (LD) was calculated as # of lobules/cm2 in each tissue section. Breast cancer associations with LD's (total, fibrocystic, proliferative) were examined with conditional logistic regression. Odds ratios are reported per 1 SD increase in LD. Results: Each LD measure was significantly associated with involution and primary BBD histology (p<0.0001 for each). Fibrocystic (OR 1.17, 95% CI 1.06-1.28) and proliferative (OR 1.37, 95% CI 1.16-1.61) LD were each associated with case status (p≤0.001) but total LD did not reach significance (OR 1.09, 95% CI 1.0-1.20; p=0.06). LD associations were somewhat attenuated after adjusting for involution (total OR 1.04 p=0.41; fibrocystic OR 1.13 p=0.02; proliferative OR 1.28 p=0.002) and primary BBD histology (total OR 1.04 p=0.49; fibrocystic OR 1.08 p=0.15; proliferative OR 1.18 p=0.07). Conclusions: The density of proliferative lobules in benign breast biopsy tissue is related to other BBD histologic features but may provide additional breast cancer risk stratification among women with proliferative BBD. Additional research will more fully evaluate the ability of this promising novel measure to predict breast cancer risk. Lobule Density Measures (lobules per square cm) All values are Medians Total Lobule Density Fibrocystic Lobule Density Proliferative Lobule Density Overall 17.5 4.5 0.7 Cases 18.1 4.9 1.3 Controls 17.0 4.2 0.4 Primary BBD Histology Nonproliferative disease 16 3.3 0 Proliferative disease 18.6 5.8 2.7 Atypical hyperplasia 20.9 6.2 3.3 Involution Category None 28.7 5.3 1.0 Partial 19.0 5 1.2 Complete 8.5 2.1 0 Citation Format: Amy C. Degnim, Lynn C. Hartmann, Tanya L. Hoskin, Marlene H. Frost, V Shane Pankratz, Derek C. Radisky, Lorelle L. Benetti, Celine M. Vachon, Teresa M. Allers, Robert A. Vierkant, Daniel W. Visscher. Density of breast lobules in benign breast tissue and association with future breast cancer risk. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 155. doi:10.1158/1538-7445.AM2013-155

Abstract 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. Cancer Prev Res; 7(2); 211–7. ©2014 AACR.

Abstract Background: Epithelial proliferation in benign breast disease (BBD) is a well-established biomarker of breast cancer risk, and BBD tissues can be used as a platform to assess other biomarkers for breast cancer risk. Lobular involution (the degree of age-related atrophy in lobules) is a new biomarker, with greater degrees of involution associated with lower breast cancer risk. Successful application of tissue biomarkers of risk to breast tissues from normal women would be valuable for risk prediction in the general population. We hypothesized that normal breast tissue samples would differ from BBD tissues in these histologic features of breast cancer risk, with less epithelial proliferation but a similar degree of involution compared to BBD tissues. Methods: Core biopsy samples from the Mayo Benign Breast Disease Cohort Study were compared to core biopsy samples of normal breast tissue obtained from the Susan G. Komen for the Cure Tissue Bank at IU Simon Cancer Center (KTB), a unique resource of breast tissue from donor women without any known breast abnormalities. All core biopsies were assessed histologically by a single breast pathologist for degree of epithelial proliferation (classified as non-proliferative, proliferative without atypia, or atypical hyperplasia) and extent of lobular involution (classified as none, 1-24%, 25-74%, or >75% of lobules). Data were analyzed using chi-square tests and logistic regression. Results: Overall, 318 Mayo BBD and 303 normal (KTB) core breast biopsy samples were evaluated. As anticipated, significantly less epithelial proliferation was present in normal samples compared to BBD samples. Proliferative disease occurred in 9/303 (3%) of normals versus 79/318 (25%) of BBD, and atypical hyperplasia was seen in 2/303 (0.7%) of normal samples versus 24/318 (8%) of BBD core biopsies, p < 0.0001. This difference remained significant after adjusting for age (which was greater overall in the BBD samples). Complete involution was more frequent in normal compared to BBD tissues, although the difference did not reach statistical significance. The age-adjusted odds ratio of complete involution in normal versus BBD tissues was 1.46 (95% CI 0.98-2.17, p = 0.06), suggesting a possible delay or failure of involution in women with BBD. Conclusions: Histologic features of normal breast tissues are different from those of BBD tissues, with less epithelial proliferation and more lobular involution, consistent with a lower risk of breast cancer expected for women with normal breast tissue compared to those with benign breast disease. Normal breast tissues are a valuable and distinct resource that should be considered for biomarker validation studies. Citation Information: Cancer Prev Res 2010;3(12 Suppl):B23.