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RESEARCH PRODUCT

Consistency in biomarkers expression between matched tissue microarray cores from primary gallblader and ovarian cancers

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Introduction. Tissue microarray (TMA) technique has been widely used, especially in immunohistochemical assays of new prognostic and predictive markers. The main objections raised by its opponents are the small amount of sampled material and the associated risk of inadequate assessment of analysed expression, resulting from the potential heterogeneity of tumour tissue. Material and methods. This study evaluated the compatibility of biomarker expression in two independent tissue cores, 1.5 mm in diameter, obtained by TMA technique from patients with gallbladder cancer (ERb, cytoPgR, HER2, CTGF) and ovarian cancer (PTEN, BCL2, PIK3CA, IGF1R). Comparison of the expression of individual biomarkers between cores was performed using the intraclass correlation coefficient (ICC), assuming a kappa < 0.4 as a weak, ≥ 0.4 as sufficient, ≥ 0.6 as good, and ≥ 0.75 as optimal correlation, and Kendall’s tau test — ICC package. Results. Evaluation of biomarker expression in the primary tumour was performed in 60 patients with gallbladder cancer and in 64 patients with high-grade serous ovarian cancer. Additionally, in patients with follicular cancer, the expression of the tested markers was assessed in the epithelium free from neoplastic malignancy. In both tumours, a good or sufficient level of homogeneity was observed in the expression of the analysed biomarkers between tissue cores. The correlation coefficient for the expression of individual markers in gallbladder cancer and adhering healthy tissue was: 0.68 (95% CI: 0.53–0.79)/0.62 (95% CI: 0.39–0.78) for ERb, 0.44 (95% CI: 0.23–0.61)/0.77 (95% CI: 0.61–0.87) for cytoPgR, 0.77 (95% CI: 0.65–0.85)/0.66 (95% CI: 0.44–0.80) for HER2, and 0.68 (95% CI: 0.53–0.79)/0.62 (95% CI: 0.39–0.78) for CTGF. In patients with ovarian cancer, the correlation coefficient within the primary tumour was 0.82 (95% CI: 0.71–0.89) for PTEN, 0.84 (95% CI: 0.75–0.90) for BCL2, 0.71 (95% CI: 0.56–0.81) for PIK3CA, and 0.77 (95% CI: 0.65–0.85) for IGF1R. Conclusions. Tissue microarray technique allows reliable assessment of the expression of tissue biomarkers within the primary tumour of gallbladder cancer and ovarian cancer