Low concordance of biomarkers in histopathological and cytological material from breast cancer

Authors

  • Gustav Stålhammar,

    Corresponding author
    1. Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
    2. Department of Clinical Pathology, Karolinska University Hospital, Stockholm, Sweden
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  • Gustaf Rosin,

    1. Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
    2. Cancer Center Karolinska, Stockholm, Sweden
    3. Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
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  • Irma Fredriksson,

    1. Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
    2. Department of Breast and Endocrine Surgery, Karolinska University Hospital, Stockholm, Sweden
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  • Jonas Bergh,

    1. Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
    2. Cancer Center Karolinska, Stockholm, Sweden
    3. Department of Oncology, Karolinska University Hospital, Stockholm, Sweden
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  • Johan Hartman

    Corresponding author
    1. Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
    2. Department of Clinical Pathology, Karolinska University Hospital, Stockholm, Sweden
    3. Cancer Center Karolinska, Stockholm, Sweden
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Abstract

Aims

The aim of this study was to investigate in primary breast cancer the congruency of routine clinical predictive biomarker evaluations, including ER, PR and Ki67, obtained using immunocytochemistry (ICC) and immunohistochemistry (IHC).

Methods and results

Clinicopathological data were collected on all women diagnosed with primary breast cancer at Karolinska University Hospital in 2011. A total of 346 patients were included in a retrospective paired comparison of predictive biomarker evaluations on direct smear ICC and IHC. This showed a low congruency between findings with the two methods, especially evident for Ki67 (κ = 0.35–0.42). By suggested adjustments to ICC cut-offs, we managed to improve the inter-rater agreement of Ki67 classification slightly to κ = 0.46.

Conclusions

Our findings suggest that routine clinical ICC and IHC evaluations of predictive biomarkers produce discordant results. Consequently, basing therapeutic decisions on cytology with cut-offs defined for IHC induces a risk that patients will receive suboptimal therapy. However, our analysis shows that local adjustments to biomarker cut-off levels may improve congruency and increase the probability of correct classifications.

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