Tissue Microarray Technique in Evaluation of Proliferative Activity in Invasive Ductal Breast Cancer

Aim: Investigation of the relationship between expression of Ki-67 antigen and Minichromosome maintenance 2 (MCM-2) protein by using an immunohistochemical study on whole sections (WS) and sections of invasive ductal breast cancer (IDC) obtained in the tissue microarray (TMA) technique. Materials and Methods: Material consisted of 51 archival paraffin blocks of IDC. Tissue microarrays were composed of 0.6 mm core punches. Reactions were peformed using specific antibodies (anti-Ki-67 and anti-MCM-2). Intensity of the marker expression was evaluated using computer-assisted image analysis. For statistical purposes, three different tests were used. Results: Spearman rank correlation revealed a strong positive correlation between expression of tested markers: Ki-67 (TMA) vs. Ki-67 (WS) (r=0.91, p<0.05) and MCM-2 (TMA) vs. MCM-2 (WS) (r=0.87, p<0.05). Mann Whitney U-test showed no significant differences between the two markers in both analysed techniques. Moreover, the Bland-Altman plot demonstrated a low level of bias between the analysed methods. Conclusion: This study shows that TMA could have a great potential in evaluation of proliferative activity in IDC and that MCM-2 protein might he a specific and sensitive marker of cell proliferation.