Metadata and data supporting the published article: Association between Low Estrogen Receptor Positive Breast Cancer and Staining Performance

Using digital analysis and quantitative tools, the authors compared the dynamic range of nuclear estrogen receptor (ER) expression in normal background ductal profiles in patients with low (1-10%) ER tumors, to the dynamic range of ER expression in normal epithelium from control patient populations (using a normal benign breast tissue (TMA) and sections of clinical control tumour cases), to determine if low ER cases are accompanied by decreased dynamic range.<br><b>Data access</b>: Dataset <b>Prelim TMA v Low ER Data Summary.csv </b>supporting figures 2 and 3 of the published article, is publicly available as part of this figshare data record (<b>https://doi.org/10.6084/m9.figshare.11482665</b>). Dataset low ER and control patient and tumor data.xlsx supporting table 1 of the published article is not publicly available in order to protect patient privacy, but can be made available on reasonable request from the corresponding author Dr. Emily Reisenbichler; Yale School of Medicine; Assistant Professor, Department of Pathology; email: <b>[e-mail]</b>.<br><b>Study approval and patient consent</b>: Tissue and associated clinico-pathological information were used after approval from the Yale Human Investigation Committee (protocol # 9505008219). Given the retrospective nature of the study, a waiver of written consent was granted.<br><b>Study aims and methodology</b>: This study aimed to examine the association between low estrogen receptor positive breast cancer and staining performance. The authors hypothesized that low ER positive cases may sometimes be a result of poor staining performance and that it may be possible to detect this artefact by assessing the average dynamic range of normal ducts adjacent to low ER positive tumors.<br>The pathology database search identified that ER immunohistochemistry (IHC) was performed on 3786 cases of invasive breast carcinomas following the updated 2010 ASCO/CAP guidelines, 40 (1.05%) of which were reported as demonstrating low (1-10%) ER expression. Glass slides of the original ER stained sections were retrieved from the archive for digital scanning.Two different normal controls were used. The first control set utilized a tissue microarray (TMA), YTMA-55, constructed of tissue obtained from the archives of the Pathology Department at Yale University, consisting of 0.6 mm cores of normal breast tissue collected in 1981 and 1982. This set was utilized as a normal level of ER expression in benign breast tissue. The second group of normal control cases included benign background epithelium from sections of invasive breast carcinomas tested for ER by IHC in the Yale clinical laboratory.<br>The number of samples used in the study is as follows:Low ER tumor patient samples = 21Control ER tumor patient samples = 34Normal breast patient samples = 10<br>For details on the immunohistochemistry procedure, quantitation of the immunohistochemistry images and statistical analysis, please read the published article.<br><b>Data supporting the figures and tables in the published article</b>: Dataset <b>Prelim TMA v Low ER Data Summary.csv</b> is in <b>.csv </b>file format and supports figures 2 and 3 of the published article. The table consists of 5 columns:Column “Centroid” consists of computer-generated numbers that were not used.Column “id” lists the “id” with each individual number representing a separate breast/patient. Each row within a single patient case number represents a separate ductal profile evaluated for the specimen (for example, rows 2-4 represent the readings from 3 separate ductal profiles on case/patient sample 1).Column “group” reports the name of the testing cohort that each case belongs to (YTMA was benign normal tissue control subset; Low ER was the clinical study set; Normal ER is the control clinical tumor cases)<br>Column “Nuclear DAB OD mean” shows the mean nuclear optical density reading of the nuclear staining seen within the specific ductal profileColumn “Pos Obj Ct” shows the the number of individual nuclei with detectable staining in that particular ductal profile.<br>Dataset <b>low ER and control patient and tumor data.xlsx </b>is in <b>.xlsx</b> file format and supports table 1 of the published article. The dataset contains patient information (including demographics and clinicopathologic tumour features).<br>