Abstract P5-06-02: Proliferative breast disease identified by nipple aspirate fluid cytopathology has the laterality and asymmetry characteristics of breast cancer, supporting the thesis it is a cancer precursor
Authors: Kylstra JW , Kalnoski MH , Vo T , Lee ML , Chen S-C , Quay SC 
Published: May 2016

Abstract
Introduction. Within the basket of conditions known as Benign Breast Disease, Proliferative Breast Disease (PBD) is a finding at biopsy or aspiration of either benign hyperplasia or atypical hyperplasia (ADH). PBD is known to confer increased risk of future breast cancer [Hartmann, NEJM 2015;372:78-89]. However, there is some controversy as to whether these lesions are precursors to breast cancer (BCa), in which their synchronicity and asymmetry should match BCa, or alternatively, if they are biomarkers of risk, in which future cancers would not necessarily be linked in time and space to earlier PBD lesions. The Left-dominant asymmetry was first described over half a century ago, but its molecular origins in embryonic development have only recently been characterized.[Wilting. J.Current Medic Chem 2011; 18:5519-27]. This study was conducted to explore if a similar pattern of asymmetry and unilateral v. bilateral incidence might exist in PBD. This could help to resolve the question of whether PBD is a precursor to BCa or merely a biomarker.
Methods. We examined Nipple Aspirate Fluid (NAF) for evidence of proliferative cytopathology, defined as a finding of either hyperplasia or ADH. NAF was collected using either one of two models of aspirator devices (ForeCYTE™ or HALO™). NAF is aspirated, dispersed on a flower filter, sprayed with fixative and stained with the Pap stain prior to cytologic characterization. Filters mounted whole on glass are placed directly under the microscope. This method allows for a diagnostically interpretable specimen in NAF-droplets as little as 0.007 µL, 1000-fold smaller than the unassisted visual detection limit. A central lab evaluated all specimens.
Results. Between 1/2012 and 6/2013, 1154 women without prior BCa (Age range 18-85; median 48, mean 47.9) consented to submit bilateral NAF specimens; 99.7% of breasts yielded NAF adequate for analysis, evidenced by presence of a duct-selective protein assay on the filter. PBD was found in 149 women, of whom 24 bilateral. The distribution is shown in the table below.
Distribution of benign and atypical hyperplasia among 149 women with PBD Left-onlyRight onlyBilateralCCR 4594218CCR 51684CCR4 (L) and CCR5 (R)--2Total Women755024King Classification: CCR4 = Benign hyperplasia; CCR5 - Atypical Hyperplasia (ADH)
Benign hyperplasia was found in 121 women: 10.5% of those tested. It was bilateral in 13% of cases and left-sided only in 57%. ADH was found in 30 women or 2.6% of those tested. When present, ADH was bilateral in 13% (4/30), L-sided only 53% (16/30) and R-sided only 33% (10/30) of the time. Total PBD identified by NAF cytopathology occurred in 13% (149/1154) of this population, was bilateral in 16.1% (24/149), L-only in 50.3% (75/149)and R-only in 33.5% 50/149). The excess left-sided occurrence of 17% was significant (p=0.048 by chi-square).
Conclusion. This is the first report describing laterality and symmetry of PBD as made by non-invasive NAF collection and demonstrates that the pattern observed is similar to what is seen with invasive breast cancer and in situ lesions, supporting the hypothesis that PBD are precursor lesions to breast cancer.
Citation Format: Kylstra JW, Kalnoski MH, Vo T, Lee ML, Chen S-C, Quay SC. Proliferative breast disease identified by nipple aspirate fluid cytopathology has the laterality and asymmetry characteristics of breast cancer, supporting the thesis it is a cancer precursor. [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 P5-06-02.