Storage Conditions and Immunoreactivity of Breast Cancer Subtyping Markers in Tissue Microarray Sections.
Author(s): Omilian AR, Zirpoli GR, Cheng TD, Yao S, Stein L, Davis W, Head KL, Nair P, Khoury T, Ambrosone CB, Bshara W
Publication: Appl Immunohistochem Mol Morphol, 2020, Vol. 28, Page 267-273
PubMed ID: 31205070 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of tissue microarray section storage duration and condition on breast cancer marker staining of formalin-fixed, paraffin-embedded (FFPE) breast tumors.
Conclusion of Paper
There were no significant differences in number of positive cases for ER, PR, and HER2 between tissue microarray sections stained immediately and those stained after storage, regardless of duration or condition. Paraffin-dipped sections were significantly less likely to be Ki67 positive after 1 month of storage and EGFR positive after 1 week, 1 month, and 6 months of storage compared to sections stained immediately after sectioning. Interestingly, the number of cases that were CK5/6 positive were lower only after 1 week of storage compared to all other storage durations and conditions.
Studies
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Study Purpose
This study investigated the effects of tissue microarray section storage duration and condition on breast cancer markers staining of FFPE breast tumor specimens. Tumor tissue cores (collection and processing details not provided) were obtained from 148 breast cancer patients (60 patients positive for ER, PR, and HER2 markers and 88 with triple-negative breast cancer). Three 0.6 mm formalin-fixed, paraffin-embedded tumor tissue cores per patient were arrayed into a paraffin block. Tissue microarrays were sectioned (4 μm) and stained immediately (fresh) or after storage at 4°C, at -20°C, or at -80°C, in a desiccator at room temperature, or paraffin-dipped at 4°C after 1 week, 1 month, 6 months, or 12 months. Sections were stained in an autostainer (60 cases for ER, PR, and HER2 and 90 cases stained with Cytokeratin 5/6, EGFR, and Ki67) and digitally scanned using Aperio Scan-Scope XT with ×20 bright-field microscopy.
Summary of Findings:
There were no significant differences in number of positive cases for ER, PR, and HER2 between tissue microarray sections stained immediately and those stained after storage, regardless of duration or condition. Compared to immediately after sectioning, paraffin-dipped sections had a lower percentage of Ki67 positive cores after 1 month of storage (57.8% vs. 73.3%, P=0.02) and EGFR positive cores after 1 week, 1 month, and 6 months of storage (P=0.005, P<0.0001, and P=0.001, respectively). However, there was no significant difference in EGFR positivity rate after 12 months of storage compared to freshly stained sections. Sections stored in a desiccator at room temperature showed no differences in number of cores staining for any of the markers, regardless of storage duration. Interestingly, the number of cases that were CK5/6 positive were lower only after 1 week of storage at 4°C, -20°C, or -80°C when compared to all other storage durations and conditions (P=0.03, all).
Biospecimens
Preservative Types
- Frozen
- Formalin
Diagnoses:
- Neoplastic - Carcinoma
Platform:
Analyte Technology Platform Protein Tissue microarray Protein Immunohistochemistry Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage conditions Paraffin-dipped
In a desiccator at room temperature
Tissue microarray Specific Targeted peptide/protein ER
PR
HER2
Cytokeratin 5/6
EGFR
Ki67
Storage Storage duration 1 month
6 months
12 months
None
1 week
Storage Storage temperature Room temperature
4°C
-20°C
-80°C