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Published on: August 1, 2018
Immunohistochemistry of breast tumor markers on archived bouin-fixed paraffin-embedded tissues
Jean-François Gagnon1, François Sanschagrin, Simon Jacob
1Service de Pathologie Département de biologie médicale, Université Laval, Québec, Canada.
Insights
Archived Bouin-fixed tissues can be used for immunohistochemistry (IHC) of breast cancer markers. Adjusting the positivity threshold for Bouin-fixed samples improves concordance with formalin-fixed tissues.
Area of Science:
- Pathology
- Biomedical Research
- Cancer Diagnostics
Background:
- Neutral-buffered formalin is the standard fixative for pathology.
- Bouin's solution is an alternative fixative used for specific tissues.
- Assessing the utility of Bouin-fixed tissues for immunohistochemistry (IHC) is crucial for retrospective studies.
Purpose of the Study:
- To evaluate the feasibility of using Bouin's solution-fixed breast tissue for IHC analysis.
- To determine the concordance of IHC results between formalin-fixed and Bouin-fixed tissues.
- To optimize IHC protocols for Bouin-fixed tissues using markers commonly studied in breast cancer.
Main Methods:
- Compared IHC results of 12 clinical markers on paired formalin-fixed and Bouin-fixed breast cancer tissues.
- Quantified marker expression using an automated system.
- Calculated concordance percentage and kappa (κ) statistic for both fixation methods.
Main Results:
- Initial analysis with a ≥10% positivity threshold showed 83.9% concordance (κ=0.65).
- Lowering the positivity threshold to 3%-4% for Bouin-fixed tissues increased concordance to 96.8% (κ=0.92).
- Automated quantification facilitated accurate marker assessment across different fixation methods.
Conclusions:
- Archived Bouin-fixed tissues are suitable for IHC analysis of breast cancer markers.
- Adjusting the positivity threshold for automated quantification is key for high concordance.
- This approach enables the study of IHC markers on valuable, long-term archived tissues.
Abstract:
Neutral-buffered formalin is the most commonly used tissue fixative in pathology laboratory. Among other fixatives, Bouin's solution has been used in several laboratories and is still in use for particular tissues. In this project, we determine if we can study breast clinical markers on archived Bouin-fixed tissue samples with immunohistochemistry (IHC) protocols optimized for tissue fixed in neutral-buffered formalin. To evaluate the concordance of IHC results between formalin-fixed and Bouin-fixed tissues, we calculated the concordance percentage and the κ statistic of 12 clinical IHC markers quantified by an automated system on breast cancer tissues fixed in neutral-buffered formalin and their corresponding tissues fixed in Bouin's solution. When positivity threshold of immunostaining was setup at ≥10% for both fixation conditions, we observed a concordance percentage of 83.9% (κ=0.65). However, when positivity threshold of immunostaining was lowered to 3% to 4% for Bouin-fixed tissues, concordance percentage was then of 96.8% (κ=0.92). Our data demonstrate that we can study IHC markers on archived Bouin-fixed tissue from patients with long clinical follow-up using IHC protocols optimized for formalin-fixed tissues after an adjustment of the positivity threshold of immunostaining quantified by an automated system.
